Malignant Melanoma 25

Introduction

In most cases, malignant melanomas spread first into lymph nodes, before hematogenous metastases develop. However, as is well known, ªexplosiveº and disseminated, hematogenous metastasis can also occur in very early stages (Fig. 1).

Exclusion of Nonmalignant, Nonmelanoma Lesions of the Skin

In the early 1960s some German dermatologists propagated the opinion that malignant melanomas should be diagnosed ªby eye and by palpationº and that radiation therapy should then follow. This opinion was certainly mistaken and was also danger- ous, because it meant that benign nonmalignant le- sions were treated with high-dose radiation therapy.

Every experienced dermatologist and patholo- gist is familiar with these melanoma-like lesions, which are:

·

Pigmented seborrhoic verrucae

·

Hemangiomas with local bleeding and siderin deposits stored in macrophages

·

Pigmented basaliomas

·

Tinea nigra

Dermatoscopic investigations are useful in the dif- ferential diagnosis. Subtle changes in surface struc- tures: pigmented network, brown globules, white spots or grayish-blue areas are changes or criteria that can be of diagnostic value. Photodocumenta- tion can also be helpful, making it possible to fol- low unclear lesions over a certain time period. It is not permissible to use such procedures for obser- vation in cases where there is a high suspicion of malignancy, however.

When molecular biological methods are used for melanoma staging, detection of tyrosinase ac- tivity in the blood is important, as tyrosinase is a

precursor enzyme for melanin formation. Detec- tion of tyrosinase-coding mRNA as a marker for melanoma cells can theoretically be usefully at- tempted in blood and lymph node investigations.

Because in normal conditions no tyrosinase- producing cells or messenger RNA of such cells are present in either the corpuscular or the liquid components of the bloodstream, investigations of the blood by the highly sensitive RT-PCR proce- dure are helpful in follow-up investigations, while assumptions of lymph node infiltrations based on positive RT-PCR results seem to be of questionable value (see also Chapters 4, 21).

There are various pitfalls that we should try to avoid:

·

mRNA coding tyrosinase released from apoptot- ic or necrotic cancer cells of malignant melano- mas can be transported via the lymph stream to the node(s) and give a false-positive reaction.

·

Normal or preneoplastic nevus cells can also be transported to the node and give false-positive reactions suggesting neoplastic spread of malig- nant melanoma cells.

These are obviously the main points that can lead- ing to false conclusions.

Macroscopic Criteria for Malignant

Melanoma Development in Pre-existing Nevi Internationally, there have been many campaigns for early detection of malignant melanomas. It is clear that all doctors in all the different medical disciplines must be familiar with the characteris- tics of this cancer. This is easy to understand, be- cause even specialists responsible for different branches of medicine can detect primaries in their own ªworking fieldsº within the human body.

Some striking features are summarized in the so- called ABCD formula:

Chapter 25

Malignant Melanoma 25

A stands for Asymmetry, which is consistent with focally increased growth activities, especially in the margins.

B stands for Begrenzung (German for delineation), meaning lack of sharpness in the periphery with incipient horizontal invasive growth.

C stands for Colorit, meaning changes in the homogeneity of coloration, which can take the form of either decoloration or hyperpigmenta- tion, according to the progression of subclonal growth.

D stands for Diameter (German ªDurchmesserº), changes in this corresponding to growth.

All these features are well known and should therefore only need to be mentioned in this con- text as a prelude to stressing the absolute impera- tive of recognizing that, in any case of these alarming signals developing in nevi, there is no time to lose and treatment must be begun imme- diately. This is stated so emphatically because even now, in many cases treatment is not started until 2±3 months after malignancy is first suspected.

Initial Risk of Tumor Progression,

Risk of Recurrence, and Definitive Risk to Survival In a multicenter study conducted at the M.D. An- derson Cancer Center in 580 melanoma patients, the SLN status was found to be the most signifi- cant prognostic factor with respect to disease-free survival and disease-specific survival according to

univariate and multiple covariate analyses.

Although the thickness of the primaries and ul- ceration influenced survival in SLN-negative cases, these properties provided no additional prognostic information in SLN-positive cases. Therefore, SLN exploration is beneficial, allowing an idea of the prognosis and the identification of patients who may benefit from early lymphadenectomy (Ger- shenwald et al. 1988, 1999).

The locoregional recurrence rate in melanoma patients seems to be important for judgments about the value of the SLN concept. To obtain clear-cut information, Gershenwald et al. (1998) looked for recurrence rates and patterns in 243 stage I and II melanoma cases in which SLNs were negative. The results were: 11% with negative SLNs developed local, in-transit, and regional nodal and/or distant metastases. In 4% metastases devel- oped in the basin investigated. In 80% of the pri- marily negative nodes tumor cells were detected in serial sections supported by immunohistochemis- try (see also Chapter 21).

These data definitely show that node examina- tions performed by pathologists using only HE staining were incomplete, and that, as a conse- quence of the false-negative histopathological re- sults, the clearance of the basins was also incom- plete. It follows from this that improvements to quality and cooperation in early diagnosis can help to lower the recurrence rates.

Fig. 1.Explosion-like metastasis from malignant melanoma into the lung, which had pigmented and amelanotic metastases

Clinical Staging of Malignant Melanoma Based on EORTC Evaluation

The clinical stages related to the progression of malignant melanomas and the corresponding sur- vival rates are valuable parameters that are helpful in all further diagnostic procedures and adjust- ments to treatment. The current data published by the EORTC are presented in Table 1.

With the successful introduction of the SLN clear- ance concept (SLCC), it became necessary to ask what the indications for its implementation might be.

Because we do not possess clearly defined cellu- lar grading criteria, which could help in decisions on whether SLN extirpation should be performed, we have to look for other ways of determining cur- rent growth activity.

One important method is measurement of the proliferative activity in tumor sections after staining with the antibody MiBI. From our own investiga- tions with this antibody in melanoma research, we know that there is a close correlation between the percentage of MiBI-positive cancer cells and region- al metastatic cancer progression, but we cannot ex- ploit this fact in decision making, especially when decisions on SLCC have to be made, because there are many other factors, such as microsatellite insta- bility, that also influence the metastatic potential.

More informative and useful for decision making are the data on degree of invasion, which can be eas- ily obtained early in the course as specified by Clark and Breslow (see Tables 2, 3). When these two well- known schemes are compared for practicability we cannot avoid the observation that the scheme ori- ented on the specific subepidermal fiber structures

(Clark) is too anatomically slanted and therefore much more difficult than measurement of the depth of invasion as described by Breslow. While we agree that local Breslow-scheme-based staging is a very important factor in the assessment of 5-year surviv- al, there is some uncertainty about whether investi- gation of the SLN(s) is necessary.

There seem to be three possibilities:

·

Investigation of the SLN(s) in all cases with in- vasive malignant melanoma

·

A threshold set at a depth between 0.75 and 1.5 mm, derived from the survival rates (see Ta- ble 3)

·

Adaptation to the different Clark levels (Table 2).

The Breslow risk scaling and results already ob- tained have given rise to the following scheme for intervention:

·

a) Sentinel node extirpation in all cases of ma- lignant melanoma of nodal type and clearance of the basins in lymph node-positive cases.

·

b) Same procedure in superficial spreading ma- lignant melanoma with a depth of invasion

>0.75 mm.

Because of the worldwide campaigns to reduce the incidence of malignant melanoma, in recent decades

Table 1. Basic stage-related data of malignant melanomas presented by EORTC

Stage Tumor status 5-Year

surviving rate Stage I Primary without signs of

lymph node involvement ~80%

Stage II Regional metastasis: ~35%

a) Satellite or in transit metastases

b) Lymph node metastases Stage III Distant (hematogenous)

metastasis ~5%

Table 2.Degree of invasion of malignant melanoma accord- ing to Clark et al.

Level I Intraepidermal melanoma=melanoma in situ

Level II Perforation of basement membrane and infiltration of stratum papillare Level III Infiltration to the border of stratum

reticulare

Level IV Infiltration of stratum reticulare Level V Infiltration into subcutis

Table 3. Prognostic risk groups by tumor thickness accord- ing to Breslow (1970, p 902)

Tumor thickness

(mm) Risk scale 5-Year survival

rates (%)

³0.75 Minimum 96±99

0.76±1.5 Low 87±94

1.51±4.0 Intermediate 66±77

>4.0 High < 50

more patients have been diagnosed in earlier stages and with thinner primary lesions. [For information on stage I disease see Veronesi et al. (1977), Balch et al. (1982) and McCarthy et al. (1985).] This is a very important advance, because after locoregional pro- gression with lymph node involvement the 5-year survival rate is reduced by 40% (Mazzuka et al.

2000). A high proportion of patients with thin (<0.76 mm) melanomas are cured by surgical exci- sion only. However, 2±18% of such patients (Fear- field et al. 2001) relapse over 0±11 years with local or distant metastases, and some of these die. So far, we have no significant molecular markers that allow accurate determination of which very thin (early) melanomas will relapse.

No absolutely clear basis for recommendations on these features is possible at present, because the biological behavior can vary widely even in cases with very small primaries and cannot be an- ticipated (a high degree of subcloning may play an important part); in addition, it is impossible to set up prospective randomized studies, as these would be unacceptable for ethical reasons.

These are not the only problems: we also have to ask whether the SLN concept has to be adapted

for the different subtypes within the malignant melanoma family. The main features of each of the different entities are listed in Table 4.

The two most important subtypes are superfi- cial spreading melanoma (65±70%) and the nodu- lar type of malignant melanoma (15±25%).

Whereas the superficial spreading melanoma grows predominantly horizontally in the early stages (invasion depths of >0.75 mm are seldom reached, or only late in the course), the nodular type grows primarily vertically from the start and therefore reaches a greater depth even in short time periods. It is mostly younger or middle-aged people who develop this type. Because of the poor prognosis in view of the fast growth, operative re- moval of the primary, including the lymphatics to the sentinel node(s) (if possible) and the SLN(s) themselves, must be performed immediately.

A third entity in the melanoma family is lentigo maligna melanoma. This is characterized by a long-term precancerous status signaling genetic in- stability. It develops mostly in sun-exposed skin areas. This type accounts for only approximately 5% of all melanomas, i.e., is far less common than either of the main types discussed above. Sponta-

Table 4.Tumor types and biological behavior of the different subtypes of malignant melanoma (m.m.) of the skin Clinical and his-

topathological subtype of m.m.

Percentage in total group

Preferred age group (years)

Clinical

characteristics Prestages Macroscopic

features Prognosis Superficial

spreading malig- nant melanoma (SSM)

65±70 40±60 Anamnesis short Nevi with junctional activity

Long-term horizontal tumor growth

Good

Nodular type of

m.m. (NM) 15±25 20±40 Anamnesis short Nevi with

junctional activity

Fast vertical tumor growth ulceration frequent, bleeding possible

Poor

Lentigo maligna melanoma (LMM)

5 >60 Long-time pre-

cancerous state (decades)

Precancerosis with develop- ment to fully malignant melanoma

Flat tumor with discolor- ation zones of vertical growth in sun-exposed epidermis

Intermediate, partly with local, sponta- neous regres- sion of tumor growth Acrolentiginous

melanoma (ALM) 5 65 approx. Aggressive tumor, phalanges, pal- mar, plantar epithelium

Irreg. pig- mentation, erosions, hy- perkeratosis

Lentiga maligna like DD.: Tinea nigra

Poor in some, because of difficulties in surgical treat- ment

neous regression with scar formation is sometimes found, which may be connected with instability of the genome. In a consideration of the features de- scribed the following points are of interest with reference to the clinical treatment to be adminis- tered:

·

The slow development of the terminal malignant lesion gives time for good practice in therapy planning.

·

It seems clear that the lesion should be opera- tively excised with sufficiently wide tumor-free margins, which must be monitored in all parts by the pathologist involved.

·

The sentinel node(s) can be labeled preopera- tively when the lesion has been present for so long that signs of malignant transformation (in- creasing discoloration, focal increased vertical growth) must be seriously expected and region- al lymphatic spread cannot be excluded.

·

In incipient developmental stages (check the his- tory) of a precancerous lesion that has remained stable for an accurately measurable period, prep- aration of the lymphatic cord together with SLN resection seems like overtreatment.

The fourth entity in the melanoma family, acrolen- tiginous melanoma with localization in the periph- ery of the extremities and in mucosal areas, is also rare and does not basically involve a higher degree of malignancy, but as far as locoregional tumor clearance is concerned its treatment is more diffi- cult. When it is localized in the lower leg, SLN de- tection can helpin selection of the cases in which it seems popliteal node excision would be of value and of those in which inguinal lymph nodes should be excised and histopathologically investi- gated (see also Fig. 2).

Clinical staging of malignant melanomas ac- cording to the EORTC scheme is a valuable way of measuring the 5-year survival rates under the con- ditions that were in place at the time of the initial histopathological diagnosis.

With respect to the SLCC, it can be concluded that improvement of the radiodiagnosis in terms of finding the locoregional lymph nodes, and by strong and more precise definition of the SLN(s) in a very high percentage of cases, we can be cer- tain that the stage I position can be improved from approximately 80%, as now, to 90% or more. In stage II, the development of satellite and in transit metastases, which have an important role in malig- nant melanomas on the legs, cannot be influenced,

but the more clear-cut definition or localization of the SLNs in the case of melanomas of the trunk and their excision in node-positive cases with me- ticulous examination of the sentinels and the nodes in the basins may improve the success rate.

In Transit Metastasis, Double or Multiple Drainage, Bypass and Atypical Metastasis

In transit melanomas are characterized by an ag- gressive behavior with recurrence and are asso- ciated with a poorer prognosis than other types of metastasis. Intralymphatic trapping of melanoma

Fig. 2.Sentinel node localizations in dependence on location of primaries: a Tumors of sex organs (penis, scrotum, vulva) and of the anal region have their sentinel nodes predominant- ly in the medial groupof the inguinal nodes (for upper medial groupsee also Chapters 28, 29). b Malignant melanomas, syn- ovial sarcoma etc. on the thigh (skin and deeper localizations, e.g., myogenous or developing from fasciae) metastasize into the node along the femoral vein, while c the corresponding tumors on the lateral and dorsal parts of the lower leg and foot metastasize via the popliteal nodes

cells between the primary and the regional lymph nodes seems to be the reason for local adhesion and breakout from the lymphatics.

Nakayama et al. (2001) found a loss of hetero- zygosity (LOH) in 19 (76%) of 25 cases. The can- cer cells of the in transit metastases were clonal in origin.

In parallel with these results, free circulating DNA microsatellites with LOH can be found in melanoma patients. Taback et al. (2001) detected LOH in 32 of 57 patients (56%) and found a sig- nificant correlation between LOH and microsatel- lite marker D1S228 in the plasma of patients with advanced disease (P=0.0009). The authors suggest that blood testing for circulating tumor genetic markers may provide prognostic information that can be turned to good account in further treat- ment planning.

How in transit metastases in the subcutaneous tissue can be detected in early stages remains an open question. Preliminary data are discussed in some published case reports (Vidal et al. 1998).

Multiple drainage pathways have been seen in more than half of the cases in melanoma studies.

These results helpsurgeons towards correct stag- ing (Mudun et al. 1996).

With respect to bypass metastasis, direct lym- phatic drainage from the skin tumor on the fore- arm to the supraclavicular lymph nodes, bypassing the axillary lymph node group, has been demon- strated by lymphoscintigraphy. This makes it pos- sible to identify patients with such metastases be- fore extensive axillary revision is planned or per- formed (Uren et al. 1996). Scintigraphic sentinel node imaging also reveals unexpected and atypical drainage patterns deviating from the conventional anatomical patterns following the lymphatics and their basins.

Uren et al. (1993, 1994, 1996, 1998, 2000), for instance, in a case of a melanoma on the left side of the back, found direct lymphatic drainage to re- troperitoneal and paravertebral nodes but no drainage to axillary or inguinal node fields or those in the triangular intermuscular space, which are the drainage areas that would normally be ex- pected.

Interval Metastases Definition and Significance

It must be recognized that interval metastases are similar to so-called in transit metastases in the gravity of their prognosis.

In transit metastases are at least sometimes out- growths of melanoma cells or cell clusters from lymphatics connecting the primary tumor region with the SLN, with infiltrative growth seen as can- cer cell nodule(s) in the skin, while an ªinterval metastasisº is a metastasis in a tiny lymph node located as an ªintermediate stationº between the primary and the sentinel node.

Interval nodes have been described as the for- gotten SLNs (Uren et al. 2000). All lymph nodes that receive any of the total lymphatic drainage, re- gardless of their location, can contain malignant cells, and with these the initial stage of a metasta- sis. This is also consistent with the knowledge that the main draining lymphatics lead directly to well- defined lymphatic basins. The interval nodes, as transitory lymphatic stations, lie along mostly long lymphatic ways leading to the main basins and can sometimes be seen or detected using the gamma probe in the course of lymphatic mapping for the sentinel node biopsy. When these sometimes very small lymph nodes are disregarded and left be- hind, the resulting metastatic melanoma can be the source of a recurrence. Such interval nodes are more common with primaries on the trunk than with primaries on the legs.

The hypothesis tested in Krew's studies was that micrometastases are just as likely to developin an interval node as in the original SLNs in the well- defined basins.

In his 13-year study program, Uren et al. (2000) found interval nodes in 148 (=7.2%) of their 2,045 patients. Micrometastases were found in 14% of these nodes. The frequency of metastatic involve- ment of these nodes is similar to that of metastatic involvement of SLNs connected to a characteristic basin.

The important conclusion drawn by Uren et al.

(2000) is that surgeons should be advised to re-

move interval nodes along with the sentinel nodes,

in order to avoid relapses in the intermediate re-

gion between primary and the SLN(s).

Morphological Stages of Development of Malignant Melanoma

and Different Main Subtypes

Differential Diagnosis against Pigmented or Nonpigmented Malignant Schwannomas

Sometimes it is difficult to delineate dysplastic nevi from malignant melanomas. Figure 3 is a macro- scopic picture that may give an impression of the changes in pigmentation. Figure 4 shows the main histological features of a superficial spreading mela- noma. This subtype is more suitable for preopera- tive labeling to detect sentinel node positions than are extended nodal types.

In Figs. 5 and 6 nodal types of malignant mela- noma are shown. In such cases sentinel node la- beling can be performed before (when the tumor is small) or after excision of the tumor (in ex- tended lesions).

Pigmented or nonpigmented malignant schwan- nomas (Fig. 7) must be considered in the differen- tial diagnosis against subcutaneous metastases from malignant melanomas. These tumors can be related to neurofibromatoses (Recklinghausen's dis- ease).

Routine versus Elective Lymph Node Dissection Routine lymphadenectomy without exact correla- tion with localization of the primary, stage, age, etc. did not result in a statistically significant ad- vantage. Therefore, primary lymph node dissection was abandoned by many surgical dermatologists for some time (Tilgen 1995). This has been con- firmed in four randomized prospective clinical trials at Sloan Kettering Cancer Center (Hochwald and Coit 1998). However, elective lymph node dis- section according to the SLN concept did give im- proved outcomes for patients aged <60 years with melanomas 1±2 mm thick, with or without ulcera- tion. Many studies have demonstrated that growth activity can be regarded as a parameter that is val- uable in assessment of the risk of regional lymph node metastasis.

Studies performed together with Korabiowska et al. (1994) showed that there was a good correlation between the proliferation of oral and skin melano- mas and lymph node involvement, whereas there was no significant correlation with local tumor ex- tension of the primary.

In earlier investigations Kaudewitz et al. (1989) had already found a close correlation between Ki

Fig. 3.Dysplastic nevus of the skin. The nevus shows partial hyperpigmentation (discoloration) (from WHO, personal gift)

Fig. 4.Superficial spreading melanoma.

Note the intraepithelial cancer cells within the epidermis surrounded by a halo, pigment incontinence with phago- cytosis in the upper corium. Loosely spread melanoma cells directly subepi- dermal

67 index and thickness of melanomas determined according to the Breslow scheme.

In most recent investigations in melanomas of man, positive nodes have been found in more than 25% of melanomas >0.75 mm thick. Alex et al.

(1998), also investigating head and neck melano- mas, suggested that preoperative lymphoscintigra- phy and intraoperative mapping with a gamma probe was a powerful approach for exact localiza- tion of SLN(s).

The

Tc-labeling solutions used for lympho- scintigraphic diagnosis depend on the place of their production. The compounds and their fre- quency of usage on the different continents are listed in Table 5.

For animal studies, a mouse model has been suggested by Nathanson et al. (1997). The authors conducted a mathematical study to check for a connection between primary extension of melano- mas and metastatic risk. They found that metasta- sis to SLNs increased in frequency with progres- sing tumor growth (g=0.976, P =0.001).

In accordance with the findings of these human studies and animal experiments, surgeons and der- matologists advise that the lymphatic basin should be rechecked after extirpation of the SLNs.

Furthermore, there is at least some hope of further improvements to treatment in connection with the introduction of interferon alpha 2b (IFNa 2b) therapy. The implications of introducing re-

isting pigmented nevus (nodular type). Note the pro- nounced elevation with flattening of the epidermal relief

(kindly donated by Prof. Kælmel, University of Gættingen) Fig. 6.Nodal type of malignant melanoma. Only in the mar- ginal area (left) is a small rest of a pre-existing pigmented nevus seen (kindly donated by Professor Kælmel, University of Gættingen)

Fig. 7.Malignant schwannoma with pos- itive S-100 reaction. Note: spindle-cell- shaped malignant melanomas show the same histological pattern. They are also S100 positive. They can be discriminat- ed by means of the antibody HMB45 (specific for malignant melanoma, schwannoma negative)

combinant IFNa 2b into adjuvant therapy regimens have been successfully tested by different clinical research groups in recent years (Kokoschka et al.

1990; Kirkwood et al. 1996, 1997, 2002 a±c; Hazard et al. 2000; McMasters et al. 2003); in spite of their results, however, it must be suggested that pro- spective studies with larger numbers of patients in the different stages are still needed. (For further information on interferon therapy the reader is re- ferred to Chapter 33.) Overall, sentinel lymphade- nectomy seems to yield a better basis for further treatment and also better final results than a ªwait-and-seeº strategy.

Historical Overview of SLN Diagnosis for Melanomas

Despite all that has been said above, Munz et al.

(1982) and Wanebo et al. (1985) had already used

99m

Tc in the 1980s to identify the lymphatic drain- age from cutaneous melanomas. Combined tech- niques using

Tc and blue dyes are meanwhile ex- cellent after intensive development and are used routinely. It is sufficient to administer

Tc the day before surgery and inject the blue dye shortly before operation (Silverstein et al. 1994; Pijpers et al. 1995, 1997; Thompson et al. 1996, 1997). This method is also good from the point of view of oper- ating teams and pathologists, the radioactive dose being kept as low as possible. The investigations of Alex et al. (1993, 1996, 1998) were focused on head and neck melanomas and showed that in cases in which SLNs were not recognized regional metasta- ses later developed. Their group confirmed the greater benefit of the lymphoscintigraphic method (96%) than of blue dye lymphatic mapping (75%).

In recently published animal studies, a contrast agent comparable to Sinerem, Combidex (Advanced Magnetics, Mass., USA), was administered s.c. and made rapid localization and identification of pe- ripheral SLNs possible (Rogers et al. 1998). These results added to the diagnostic staging of malignant melanoma achieved with MRI; however, at the mo- ment they do not actually replace the nuclear med- icine approach. In general, all criteria for a useful SLN biopsy, such as sensitivity, specificity, positive and negative predictive values, accuracy, false-posi- tive and false-negative rates, are met in the case of melanoma diagnosis (Morton et al. 1984, 1992, 1993, 1997; Caldwell and Spico 1988; Gershenwald et al. 1988, 1999; van der Veen et al. 1994; Karpteijn et al. 1995, 1996, 1997; Krag et al. 1995; Albertini et al. 1996; Miliotes et al. 1996; Mudun et al. 1996; Reint- gen et al. 1996, 1997; Ross 1996; Thompson et al.

1996, 1997; Leong et al. 1997; Ramnath et al. 1997).

In recent years, several authors have clearly dem- onstrated the effectiveness of locoregional node dis- section with biopsy (Bowsher et al. 1986; Caldwell and Spiro 1988; Drepper et al. 1993, 1994; Krag et al. 1995; Bostick et al. 1999; Peters et al. 1996; Winter et al. 1996; Alex et al. 1998; Bçchels et al. 1998; Ca- fiero et al. 1998; Dresel et al. 1998; Gogel et al. 1998;

Goldfarb et al. 1998; Hochwald et al. 1998; Schnee- baum et al. 1998). Experience clearly documents that precise surgical treatment of melanoma with wide excision and nodal staging is the most efficient procedure as far as saving life is concerned.

Meanwhile, in many hospitals at least the blue dye method is used, with much higher lymph node detection rates than when it was first introduced.

The sentinel node detection rates and the rates of false-negative cases recorded throughout the world in different centers and clinics are summarized in Tables 6 and 7.

The question of whether the distance between the tumor and the site of injection of the radiocol- loid modifies the result of lymphatic mapping in melanoma cases was investigated by Martinez-Essi- bano et al. (2001): after obtaining informed con- sent they performed two lymphoscintigraphies in each of 19 patients following narrow excisional biopsy. Intradermal injections were given 1.5 and 0.5 cm from the primary. Similar channels and sentinel nodes were revealed by both lymphoscin- tigraphies. This means that injections given less than 1.5 cm from the margins of a biopsy scar (or from the melanoma margins) still result in optimal results in terms of node labeling.

Historical Overview of SLN Diagnosis for Melanomas 339

Table 5. Use of radiopharmaceuticals for lymphoscintigra- phy at the different continents

Radiopharmaceutical Continent where most frequently used

99mTc-Human serum albumin

(SHSA)^a North America

99mTc-Sulfur colloid (SC) North America

99mTc-Nanocolloid albumin Europe

99mTc-Antimony trisulfide

colloid Australia

aSee Bedrosian et al. (1999)

Experience of management of the sentinel node biopsy and lymphatic mapping collected in most countries of the world in recent years (1998±2001) has made it clear that use of the SLN concept im- proves melanoma treatment. Therefore, the World Health Organization and the Sunbelt Melanoma Clinical Trial support the SLN concept as a stan- dard of surgical care of malignant melanomas (see McMasters 2001).

In the Sunbelt Melanoma Trial, 1184 patients with cutaneous melanomas 1mm or more thick (Breslow) were analyzed for sentinel nodes using the isosulfan blue dye and

Tc-colloid labeling methods (McMasters et al. 2001). In 24% of the cases sentinel node metastases were found. Blue dye staining was found in 86.3% of the histopatho- logically positive sentinel nodes.

In 40 of 306 positive nodal basins (13.1%) the most highly radioactive node was negative, whereas another, less markedly radioactive, senti- nel node was positive for tumor. Therefore, the authors recommend that all blue-stained nodes in which radioactive counts 10% or more above the ex vivo counts are measured and the hottest senti- nel lymph node should be harvested for optimal detection of node metastases.

Chao et al. (2002), also analyzing Sunbelt Mela- noma Trial patients, report that early regional lymph node recurrence was very uncommon after sentinel node biopsy and lymphadenectomy, whereas patients with positive SLNs were more likely than those with negative SLNs to develop both local and transit recurrences and distant me- tastases within a short follow-up period.

Table 6.Series of melanomas treated with use of the sentinel node concept

Authors Year of

publica- tion

No. of

cases Routine lymph node dissection

Sentinel node detection rate SN

positive SN false negative

Total Dye Probe

Morton et al. 1992 223 + 82% 82% ± 22% 1%

Reintgen et al. 1994 42 + 100% 100% ± 19% 0%

Krag et al. 1995 121 ± 98% 91% 98% 12% ±

Thompson et al. 1995 118 + 87% 87% ± 21% 1.70%

Albertini et al. 1996 106 ± 96% 80% ± 15%

Leong et al. 1997 163 ± 98% 74% 98% 18% ±

Lingam et al. 1997 35 ± 100% 100% ± 26%

Morton et al. 1993 72 ± 90% 90% ± 15%

Bostick et al. 1999 87 98% 94% 92% 17%

Gershenwald et al. 1999 612 93% ± ± 15% 1.30%

Morton 1999 1135 97% 95% 99% 19%

Labeling

method used SLN de- tection rate

micro metasta- sis

radiolog- icallymph nodedissec- tion

reg. Re- currence

Bçchels et al. 2000 274 ^99mTc-colloid 99.30% 53.10% 30% 1 case

Temple London

Experience 2000 2000 56 ^99mTc-sulfur colloid 10±15 MBq

98% SLN in

unpre- dicted localiza- tion32%

SLNscintig- raphy, vs opera- tion 2.3/

2.2%

Possible Ways of Searching for the Primary in Atypical or Nondermal Localizations

In approximately 5±10% of malignant melanomas detected by their metastatic spread it is difficult ± even in the case of terminal metastatic spread and on autopsy examination ± to find the primary. In such cases, all visible nevi are usually investigated both in vivo and at autopsy, but no primary with clear-cut indicators of malignancy (cellular atypia, pigment incontinence, and invasive growth) can be ascertained. However, as we know, there are three possible explanations for this.

·

It has been found on histological serial section- ing that small primaries of malignant melano- mas can develop maximal regression with pha- gocytosis of the apoptotic or necrotic melanoma cells and loss of pigment from the hair in the

pre-existing melanoma area. These facts can be ascertained by immunohistochemical staining with antibodies directed to macrophages such as CD68 or MAK387 and antibodies directed to S100 protein or the HMB45 antibody for stain- ing of characteristic melanoma antigens, which do not require intact melanoma cells. In double staining, melanoma antigens can then be found in the cytoplasm of macrophages.

·

A second possibility is that dysplastic cells of nevi are drained into lymph nodes and develop their full malignancy there.

·

The third, and still more important, possibility must be seen in the fact that the primaries of malignant melanomas can be localized within the orifices of the body, meaning

± oral cavity

± anal circle mucosa (see Fig. 8)

± head sinuses

Possible Ways of Searching for the Primary in Atypical or Nondermal Localizations 341

Table 7.Further series treated according to the SLN concept (ELND elective lymph node dissection, SLND sentinel lymph node dissection)

Authors Year of

publication No. of cases Labeling

method used SLN found Rate of

metastases Specific remarks Pizzocaro et al.:

Brescia Experi- ence (Italy)

2000 71 ^99mTc colloid 70/71(98.5%) 9/69 (13%)

Fliquete et al. 2000 65 9 Blue dye 63/65 (97%) 8/65 (12%)

56^99mTc- colloid

Mazzuka et al. 2000 ^99mTc-nano-

colloid, 15±20 MBq

24/29 (83%) 6/24 (25%) Elective node dissection in 5 (20%) Jacobs et al. 2001 103 >0.12 mm

Breslow, Clark II

99mTc-sulfur

colloid 99% Micrometas-

tases in 10% False negative rate: 8%

Davison et al. 2001Review of lit- erature on head and neck mela- noma cases (n)

99mTc colloid/

blue dye solution

95±100% 7.7±10.4%

Clary et al. 2001152 ELND con-

cept n=329 SLND metas-

tasis rate 20% ELND metas-

tasis rate 13% Local recur- rences SLND vs ELND:

72% vs 39%

(p=0.01) Tremblay et al. 200136 (18 male,

18 female), mean Breslow thickness 2.35 mm

99mTc-sulfur colloid 0.5 mCi

SLN detection

rate 97.2% Average no.

of SLN 1.97 8 (22%) positive SLN 2/7 positive nodes in complete nodedissection

± rectal mucosa approximately up to Kohl- rausch's fold

± pharyngeal mucosa

± esophageal mucosa

± vulva, vagina

± urethra.

Very occasionally, primaries develop in ovarian teratomas or on the spinal cord. [For information on treatment of gynecological melanoma treatment readers are referred to Kroon and Nieweg (2000).]

All these possible localizations must be checked when metastatic processes become obvious and no primary can be detected. In such cases with suspi- cious lymph node(s) in a defined basin, these can be investigated for melanoma cells after extirpa- tion, histologically or before operation by aspira- tion cytology. In suspicious cells pigment can often be seen in the cytoplasm as a dark greenish-brown color after Giemsa staining.

Antibodies directed to S-100 protein or the anti- body HMB45 can make specific staining of the melanoma cells possible. There is only one fact

that has to be borne in mind: that dendritic reticu- lum cells even show positive S100 protein reactions in their cytoplasm, but these cells can nearly al- ways be delineated on the basis of their dendritic cytoplasmic structures.

Malignant Melanomas of the Anal Circle and the Rectum

Search for the SLNs

Compared with patients with cutaneous melano- mas, those with anal or rectal melanomas (0.1±

4.6% of all anal malignancies; 2±3% of all malig- nant melanomas) have a worse prognosis (Ben Iz- hak et al. 1997; Helmke et al. 2001).

The 5-year survival rate is less than 10%, which is the same as in cutaneous melanoma stage IV (Coit 1993).

The reason for this unfavorable biological be- havior is not fully understood (unfavorable loca- tion? different genetically based tumor develop- ment and growth activity than in UV-induced cu- taneous melanomas?) (Balch et al. 1979; Liw et al.

1996). Only one point seems to be clear: in con- trast to malignant melanomas located higher in the rectal mucosa, melanomas of the anal circle may invade hemorrhoidal veins early and metasta- size directly into the lungs via the azygos veins.

In patients with rectal melanomas, in the search for SLNs the same principles can be applied as in the case of rectal cancer (see Chapter 26, pp. 391±

393). On the basis of new developments, peritu- moral

Tc-labeling and the search for retrorectal lymph nodes using the gamma probe seems to be a method that would reward further development.

In melanomas of the anal circle (see Fig. 8), as well as rectal amputation the search for retrorectal lymph nodes (followed by en bloc resection) is ob- ligatory in cancer clearance. In addition, it is neces- sary to search for inguinal and/or para-iliacal lymph nodes as possible sentinel nodes. Individual surgical treatment along these guidelines is the method of choice (Weinstock 1993; Whooley et al. 1997).

So far there are no data on benefits of adjuvant chemotherapy (Vorpahl et al. 1996). In conclusion, no scheme has yet been developed that would make it possible to find a single SLN or node groups in the different possible basins.

Fig. 8. Malignant melanoma of the anal epithelium, with strong pigmentation in parts (overview). Note transition to rectal glandular structured mucosa in marginal areas. These tumors are sometimes wrongly diagnosed and not detected until an inguinal metastasis is histologically verified (pic- ture kindly provided by Dr. Helmke, Department of Pathol- ogy, University of Heidelberg)

Immunohistochemical Support in the Diagnosis of Dysplastic Nevi and Early Invasive

Malignant Melanomas

For the diagnosis of dysplastic nevi and very early intraepidermal melanoma development, as well as early stromal invasion, immunohistochemical dou- ble staining, for instance using antibodies directed to S100 protein and proliferative nuclear antigen (Ki 67, MiBI), is very helpful.

Double staining of S100 protein and Ki 67 (MiBI) active against the proliferation acthive pro- tein helps to exclude increased proliferation, and with this malignancy, on the one hand (Fig. 9), or to confirm increased proliferation of S100-positive

nevus cells that are already atypical on the other (Fig. 10). In addition, early stromal invasion can be detected by these immunohistochemical stain- ing procedures.

Possibilities for Cytopathological Confirmation of the Diagnosis of Malignant Melanomas in Cancer-infiltrated Lymph Nodes in Cases with Primarily Undetected Primaries

In cases in which no locoregionally located malig- nant melanoma or other primary has been detected, suspicious, mostly enlarged, lymph nodes can be as- pirated by way of a fine needle and the smears can

Fig. 9.Dermal nevus cell nevus. The in- traepithelial and the dermal nevus cell populations are intensively stained with the antibody directed to S100 protein.

Only a few nuclei are stained with MiBI, almost exclusively basal cells of the epi- dermis

Fig. 10.Small sector of a dysplastic ne- vus cell nevus. Besides basal cells, in some higher cell layers a few nevus cells (S100 protein, positive with brown- stained granules) are also MiBI positive.

Some intraepithelial nuclei show apop- totic changes

Fig. 11a±d.Diagnosis of occult malig- nant melanomas in fine-needle aspira- tion cytology (FNAC) from lymph nodes (Giemsa and immunohistochem- ical stainings). a FNAC of an amelano- tic malignant melanoma with partly epithelial layered cell populations;

no pigment can be detected. Note round nuclei, some with central prominent nucleoli.b Amelanotic malignant mela- noma, same tumor, stained with the melanoma-specific antibody HMB45.

c Malignant melanoma cell populations with strongly positive reaction using antibodies directed to the mesenchymal cell marker vimentin (intermediary fila- ment). Note: All malignant melanomas are vimentin positive

be analyzed by Giemsa staining and immunohisto- chemically. Some characteristic stainings, illustrated in Fig. 11a±d, document the characteristic antigenic features of malignant melanomas.

Exclusion of Systemic Disease in Malignant Melanoma Cases and N-staging Supported by FDG-PET N. Avril, W. Weber, M. Schwaiger

Introduction

In patients with cutaneous malignant melanoma the clinical demands made of imaging modalities are the identification of locoregional lymph nodes and of distant metastases (Macfarlane et al. 1998).

FDG-PET has been successfully applied in the de- tection of metastases from malignant melanoma in high-risk patients (tumor thickness: >1.5 mm or invasion of Clark level IV). In numerous studies, FDG-PET has been shown to be at least as effective as combined standard diagnostic tests including CT of chest and abdomen, MRI of brain, and ultra- sound examination of the abdomen and of the re- gional lymph nodes (Figs. 12, 13).

It is clear that in cases with positive node ba- sin(s) sentinel node staging using the blue stain and/or

Tc method should only be performed when diagonal metastasis seems possible or be- comes obvious.

Exclusion of Systemic Disease in Malignant Melanoma Cases and N-staging Supported by FDG-PET 345

Fig. 11d.Malignant melanoma cell pop- ulations stained with antibodies direct- ed to cytokeratins. Note: Newer results show that a small percentage of malig- nant melanomas show coexpression for cytokeratins. The cytokeratin positivity can result in a pitfall with the diagnosis of carcinoma

Fig. 12.Melanoma with axillary lymph node metastases. The coronal PET image shows an intense focus of increased me- tabolic activity in the region of the left axilla, representing a single axillary lymph node metastasis

Locoregional T- and N-staging

Macfarlane et al. (1998) conducted a preoperative study in 23 patients with primary lesions larger than 1.5 mm who were scheduled for lymph node dissection with FDG-PET. In 13 of these patients therapeutic lymph node dissection (LND) of 14 node basins was performed, while 9 patients un- derwent elective LND of 10 node basins. With ref- erence to the regional node basins, PET imaging demonstrated 11 true-positive, 10 true-negative, 2 false-negative, and 1 false-positive findings, result- ing in an overall accuracy of 88%. It is important to note that PET failed to detect micrometastatic disease; nevertheless, Holder et al. (1998) suggest- ed a role for FDG-PET as a first-line tool in the staging of melanoma. They examined 76 patients with stage II±IV malignant melanomas to compare FDG-PET and CT scanning. In 103 PET scans a sensitivity of 94.2% and a specificity of 83.3% were noted, as opposed to 55.3% and 84.4%, respec- tively, for CT.

Misinterpretations in the PET staging investiga- tions occurred in cases with papillary carcinoma of the thyroid, bronchogenic carcinoma, inflamed epidermal cyst, Warthin's tumor of the parotid gland, surgical wound inflammation, leiomyoma of the uterus, suture granuloma, and endometriosis.

Such lesions must be clinically excluded by topo- graphical reflections and by the exclusion of in- flammatory lesions, etc.

The 4 false-negative scans were thought to be due to small (<0.3±0.5 cm) and diffuse areas of melanoma without a mass effect. Several recent studies have demonstrated the limited value of anatomically based CT scans for evaluation of stage III patients.

In a prospective study, Tyler et al. (2000) per- formed 106 whole-body PET scans in 95 patients with clinically evident stage III lymph node(s) and/or in transit melanoma. In all, 234 areas were evaluated pathologically, 165 of which were con- firmed by histological examinations to be melano- ma. PET scanning identified 144 of the 165 areas of melanoma, yielding a sensitivity of 87.3%. The 21 areas of melanoma that were missed included 10 microscopic foci, 9 foci less than 1 cm in diam- eter, and 2 foci greater than 1 cm. There were 39 areas of increased PET activity that were not asso- ciated with malignancy, resulting in a positive pre- dictive value of 78.6%. Of the 39 false-positive areas, 13 could be attributed to recent surgery, 3 to arthritis, 3 to infection, 2 to superficial phlebitis, 1 to a benign skin nevus, and 1 to a colonic polyp.

However, by employing pertinent clinical informa- tion, the predictive value of a positive PET scan was improved to 90.6%. Thirty-six (19.7%) of the total of 183 abnormal areas scanned by PET proved to be unsuspected areas of metastatic dis- ease. These findings led to a change in the planned clinical management of 16 patients following 106 PET scans (15.1%).

Eigtved et al. (2000) considered the value of FDG-PET in the detection of ªsilent metastasesº from malignant melanomas by comparing FDG- PET findings and those obtained with conventional imaging methods. Thirty-eight patients with clini- cal stage II (local recurrence, in transit, and re- gional lymph node metastases) or stage III (metas- tases to other sites than those in stage II) were in- cluded in the study. For all foci, FDG-PET had a sensitivity of 97% and a specificity of 56%, as op- posed to 62% and 22%, respectively, for the con- ventional imaging methods used. For intra-abdom-

The coronal PET image demonstrates areas of focally in- creased metabolic activity in the left inguinal region, repre- senting lymph node metastases

inal foci, the sensitivity and specificity were 100%

for both imaging approaches. However, corre- sponding figures for intrathoracic and pulmonary metastases were 100% and 33%, respectively. An important finding in this study was that 34% of patients would not have been staged correctly by conventional methods alone.

However, Krug et al. (2000) were not able to confirm such positive results for PET imaging. In a retrospective analysis of 94 melanoma patients, including 40 patients with evidence of lymphogen- ous and 42 with evidence of hematogenous metas- tasis, they found FDG-PET to be inferior to CT in the diagnosis of lung and liver metastases. In a meta-analysis of the 13 papers in the literature on detection of recurrent melanoma by FDG-PET, an overall sensitivity of 92% (95% confidence level 88.4%±95.8%) was calculated, together with an overall specificity of 90% (95% confidence level 83.3±96.1%) (Schwimmer et al. 2000). From the limited data available a directed change in man- agement value of 22% was indicated for FDG-PET.

Overall, FDG-PET was found to be insensitive as an indicator of occult regional lymph node metas- tases in patients with melanoma, because of the small tumor volumes in this population (Wagner et al. 1999). In a prospective study the same authors included cutaneous melanoma with a Bres- low's depth greater than 1 mm (stage T2±4N0M0) or localized regional cutaneous recurrence (stage Tx,N2b,M0). Eighty-nine lymph node basins were evaluated by FDG-PET and sentinel node biopsy in 70 evaluable patients. Eighteen patients (25.7%) had lymph node metastases at the time of FDG- PET imaging: in 17 these were confirmed by senti- nel node biopsy (24.3%) and in 1 by follow-up ex- amination (1.4%). The sensitivity of sentinel node biopsy for detecting occult regional lymph node metastases was 94.4%, and the specificity was 100%. The sensitivity of FDG-PET was 16.7%, and its specificity 95.8%. These results clearly indicate that FDG-PET cannot helpin the staging of region- al nodes in patients with clinically localized mela- noma. The inability of PET to identify microscopic disease suggests that it is of limited use in evaluat- ing patients with stage I±II disease. Detection of brain metastases is also limited owing to the high glucose utilization of normal gray matter. Finally, small lung metastases may be detected with higher sensitivity by spiral CT of the chest.

Concluding and Comparative Remarks

However, FDG-PET is a sensitive method and su- perior to conventional methods for detecting wide- spread metastases, and it is useful as a supplement to clinical examination in melanoma staging.

Accumulating Experiences in Sentinel Node Detection in Malignant Melanomas

Report given by Dråger et al. in Berlin in December 2000 Between 1995 and 2000, a total of 863 patients with malignant melanomas were seen in the Department of Dermatology, Charit Berlin, and 1145 sentinel lymph node biopsies were performed in all these pa- tients. When the cancers were located on the trunk, upper arm, and thigh and in the head and neck re- gion, SLN excision was combined with lymphoscin- tigraphy-guided en bloc excision from the primary along the lymphatic pathways to the SLN(s).

In their latest report, Dråger et al. (2001) sum- marized the results of a melanoma consensus con- ference held in 1999 in Berlin:

·

The search for SLN(s) is indicated for melano- ma patients with Breslow thickness >0.75 mm and/or Clark level >3 (pT2±4).

·

The sentinel node search can be performed in patients with melanoma and also in patients who have already undergone a wide excision (>1 cm safety margin).

The authors explicitly emphasize that after excision the injections must be given very carefully, because lymphatic pathways and flow can be altered.

The following points are seen as essential:

·

Performance of a lymphatic outflow scintigra- phy (LAS) using

Tc-nanocolloid, 40±20 MBq injected around the tumor.

·

Intracutaneous injection 0.5 cm away from and around the tumor or the scar after the melano- ma operation, optimally 20±24 hours before op- eration.

·

Scintigraphy should be stopped when a clear lymphatic pathway and the location of the SLN appear. The positions of the SLN(s) and path- way(s) are then marked distinctly on the skin.

·

Double injection (blue dye and

Tc-nanocol-

loid) is essential in head and neck melanomas

and in perianal and genital melanomas owing

to the complexity of lymphatic drainage, to dif- ferent basins in some cases.

The current results obtained by the Berlin group in investigations on 863 patients with 1145 SLNs are summarized in Tables 8±11.

Sugranes et al. (2001) give an overview about the positive and negative rates for SLNs in depen- dence on the clinical stage, pooling stages I and II for comparison with stage III. In stage III the sen- tinel positive rate is approximately threefold that in stages I and II (Table 12). A short overview of the overall survival rates related to the different melanoma stages reported by Dråger et al. (2001) is shown in Table 13.

Whereas in stage pT3 (1.51±4.0 mm invasion) the primary is still resectable and elective lymph node dissection (ELND) is still possible, these op- tions rapidly recede in the presence of pT4 tu- mors.

These data may be used as the basis for com- parative studies (5-year and 10-year survival rates) after SLN dissection and after detection of positive SLNs followed by more extensive controlled node dissection in the different basins.

Does it depend on Topographic Constellations whether Localization of the SLNs is Calculable or Incalculable?

In the case of melanomas on the legs, femoral and inguinal lymph nodes can be viewed as the senti- nels, because the small popliteal nodes are very difficult to detect and sometimes tumor cells by- pass them, leading to skip metastases. In rarer cases, however, especially in melanomas localized laterally on the foot and lower leg, the popliteal lymph nodes can be the sentinels with enlarge- ment of volume and outgrowth of the cancer.

One third of primaries are located in the face (often on the cheeks and in the temporal region).

For primaries in these regions, the buccal, facial, submental and cervical nodes are the ones of first involvement (see also Chapter 23). However, there is no single sentinel node that can be assumed to

diagnosed cutaneous malignant melanoma with 1145 SLN

Patients SLN

n % n %

pT12 0.2 2 0.2

pT2 404 46.8 549 47.9

pT3 363 42.1474 41.4

pT4 94 10.9 120 10.5

Total 863 100.0 1145 100.0

Table 9.Variability of the lymphatic system. Results of identi- fication and localization of the SLN by use of a combination of preoperative lymphatic outflow scintigraphy (LAS), intra- operative use of hand-held gamma probe and intraoperative coinjection of a vital dye (LM) in 863 patients with newly diagnosed cutaneous malignant melanoma with 1145 SLN

Patients SLN

n % n %

1646 74.9 646 56.6

2 166 19.2 332 29.0

3 37 4.3 111 9.7

4 14 1.6 56 4.9

total 863 100.0 1145 100.0

Table 10.Patients with SLN biopsy (SLNB) and number and percentage of positive SLN (at histopathology and immuno- histochemistry) with consecutive elective lymph node dis- section (ELND) ± data from 43 centers in Germany and Austria

Country Patients with SLNB n

ELND in case of positive SLN

n %

Germany 1591 255 16.0

Austria 290 46 15.9

Total 1881 301 16.0

Table 11.Examination of SLN and Non-SLN. ELND was per- formed after SLNB. SLN and Non-SLN were examined by histopathology and immunohistochemistry in 327 cases (100%)

SLNnegative/

non-SLN negative

SLNpositive/

non-SLN negative

SLNpositive/

non-SLN positive

SLNnegative/

non-SLN positive

n 217 67 32 11

% 66.3 20.5 9.8 3.4

be especially important. The significance of the ju- gular vein junctional node seems to be quite simi- lar in tumors of ear, nose, and throat. More inter- est attaches to the question of the sentinel nodes when a melanoma is located on the trunk, espe- cially in the mid-line of the back, or in the thorac- ic or the abdominal region on the ventral side.

Concerning these options, there may also be two or three SLNs, e.g., in the case of primaries lo- calized medially on the trunk with sentinels at

both sides in the axillary or inguinal node groups or in the contralateral axillary and inguinal nodes.

When sentinel nodes corresponding to primaries on the back were looked for, in a few cases senti- nels were also observed in retroperitoneal abdom- inal areas. For these locations of the primary, la- beling of a sentinel node would be helpful, because too-late extirpation of initial metastases, e.g. in axillary node(s), would decrease the chance of survival.

Accumulating Experiences in Sentinel Node Detection in Malignant Melanomas 349

Table 12.Comparison of positive SLNs of the stages I and II with stage III Stage

I/II(n)

SLNsharvest- ed

SLN Control lym-

phadenectomy Stage

III SLNs

harvest- ed

SLN Control-lympha- denectomy (n) In

SLNpos.

cases neg.

24 34 6 28 160 0 16 22 14 8 89 44 45

pos. neg.

No. of pos.

nodes

pos. neg.

No.of nodes pos.

Table 13.Overall survival rates of patients with primary malignant melanoma (clinical stage I of the skin in dependence of pT classification (UICC), i.e. in dependence of Breslow tumor thickness)

Reference Comments pT2 (0.7±1.5 mm) pT3 (1.51±4.0 mm) pT4 (>4 mm)

Balch et al. 1998 All tumor locations, with and without

ELND 87% 66±75% 47%

5-Year overall survival Orfanos et al.

1994 All tumor locations, with and without

ELND 90% 67% 43%

10-Year overall survival Winter et al. 1996 All tumor locations, with ELND

5-Year overall survival 99% 91% 60%

10-Year overall survival 96% 88% 60%

Tumor location on the trunk, with continuity dissection (including ELND)

5-Year overall survival 100% 91% 52%

10-Year overall survival 100% 88% 52%

Tumor location on the upper arm, with continuity dissection (including ELND)

5- and 8-Year overall survival 100% 90% 66%

Tumor location on the thigh, with continuity dissection (including ELND)

5- and 8-Year-overall survival 100% 96% 87.5%

Performance in Labeling of SLNs in Cases with Skin Tumors

In injection of blue dye solution and/or

Tc-na- nocolloid solution the assumed direction of lymph flow is important in the decision on whether injec- tions of the labeling solution should be given in a circular or semicircular formation. For instance, when the malignant melanoma is located on the skin of the trunk a circular arrangement of injec- tions around the malignant melanoma is appropri- ate in practically all cases, and when the primary

has been excised and scars have formed, precur- sive and perifocal ªcircular injectionº is also neces- sary, because diagonal (axillary and inguinal lymph nodes) or bilateral (axillary or inguinal) metastasis is possible (see Fig. 14). When the pri- mary is located on the face or extremities (arms, legs), where lymphatic flow normally runs in only one direction semicircular injection seems to be the method of choice (Figs. 14, 15). This helps to restrict the quantity of solution injected or con- centrate the

Tc dosage on the side where the semicircle of injections is given.

Fig. 14.Different localizations of cuta- neous malignant melanomas: circular and semicircular injection of the label- ing solution referred to localization of the primary and possible drainage di- rection of the lymphatic flow

Details of Injection Technique for Patent Blue Dye Solution and/or

Tc-nanocolloid Solution Some important points must be observed:

·

During the injection the angle of the needle to the surface of the skin should not be more than 158 (see Fig. 16).

·

The injection should be performed in the oppo- site direction to the melanoma infiltration. A four point injection scheme, used e.g. in mela-

nomas of the trunk, demonstrating the possible directions of the lymphatic flow, is shown in the Figures 17a and b.

·

Puncture or particle biopsy of malignant mela- nomas can propagate cancer spread and con- trast solutions must therefore be injected out- side the neoplastic lesion in every case.

·

Because removal of the primary is an urgent priority and because of difficulties in delineat- ing the margins of the neoplastic infiltrations in malignant melanoma cases, the SLN search (see Fig. 17) is often started after excision of the pri- mary with monitoring for tumor-free margins.

In such cases the SLN search is done in the same way, by injecting the labeling solutions(s) outside the wound or scar formation.

The rate at which popliteal lymph nodes are iden- tified as sentinel nodes is very low. Thompson et al. (2000) looked for the frequency of metastatic involvement of these nodes in their collective of 4,262 cases with malignant melanomas located distal to the knee. Only in 13 cases (0.31%) were popliteal metastases found. The conclusion of the authors is that surgical popliteal clearance should only be performed when there is clinical suspicion of popliteal metastatic involvement.

Demonstration of Blue Dye and

Tc-labeling in Malignant Melanoma Cases

Figure 18 shows the labeled lymphatic flow from distal to proximal in the arm, marking the direc- tion of the drainage. Figure 19 shows early labeling of the SLN in the right axilla.

The storage of the nanocolloids can be perfectly seen as soon as 20±45 minutes after injection and is still visible next day for the intraoperative search with the gamma probe.

In Fig. 20 fast labeling of two scattered lymph nodes is shown in another case. This picture in- cludes the possibility of skip metastasis.

Figure 21 demonstrates a lymph node that is the first to show upas labeled after injection of the nanocolloids and is obviously the sentinel node, but further secondary node labeling is al- ready visible 45 minutes after injection.

Figure 22 documents a malignant melanoma with the primary located on the back. After peritumoral injection rapid drainage to the right-sided axillary lymph node(s) developed, but very soon drainage to the left-sided axillary nodes also started.

Accumulating Experiences in Sentinel Node Detection in Malignant Melanomas 351

Fig. 15.For malignant melanomas of the dorsal side of the body the same criteria apply as for ventral melanomas.

Note the possibility of interval metastases in popliteal nodes

Fig. 16.Injection technique before tumor excision in malignant melanoma cases.

The same injection technique can be used when the solution(s) is/are injected after primary excision

Fig. 17a, b.The four-point injection sites to be used before tumor excision in the case of malignant melanomas on the trunk. Lymphatic drainage can takeaonebtwo or in some cases more directions. In peripheral melanoma localizations (face, legs, hands, etc.) injections need only be given in a semicircle of sites

Fig. 18.After injection of more than 30 MBq^99mTc-nanocol- loids at regular intervals around the melanoma, the lymphatic drainage from the tumor site can be visualized (right arm)

Fig. 19.Between 20 and 45 min the SLN in the right axilla can be localized in a gamma camera study; it needs to be marked on the skin surface to allow its localization next day in the operating room

Fig. 20.If the sequence of the images is fast enough (5 s/im- age), the dynamic of the lymphatic flow can be followed and the first lymph node, which is the sentinel, can be de- fined, because often a second lymph node rapidly appears in the scan. This difference is important, because in theory a skipsentinel node is possible

Figures 23 and 24 illustrate a sentinel node scin- tigraphy in a case of malignant melanoma on the leg, with labeling of a superficial iliacal SLN and also early labeling of a second SLN in the pelvic area, which may have developed because the superficial iliacal node has been bypassed.

In contrast to typical iliac superficial sentinel node shown in Fig. 24a sentinel node of a leg mel- anoma in the pelvic area (Fig. 25) seems to be really rare.

Examples of Daily Routine

In this section, results of patent blue labeling tech- niques obtained in individual cases are shown. Fig- ure 26 illustrates the strategy of patent blue labeling with semicircular injection around a scar with mul- tifocal melanoma recurrence. Fig. 27 shows lym- phangiogram using patent blue injected intrader-

Fig. 21.Image recorded 45 min after peritumoral melanoma injection of ^99mTc-nanocolloids in the right leg, already showing more lymph nodes in the iliacal region, because the sentinel has already been passed and the second and third nodes are visualized. We therefore prefer to record dy- namic images

Fig. 22. Peritumoral melanoma injection in the back, with rapid lymphatic drainage to the right axillary lymph nodes but also to the left axilla. Drainage starts at the bottom of the image on the left (arrow). An image of the left axilla shows lymph node uptake there as well

Fig. 23.If a skipmetastasis from the lesion is seen on sentinel node scintigraphy of the lower leg, the sentinel node may be in the iliacal area, either superficially or deep in the pelvic area, which needs a more complicated surgical approach. To differentiate between superficial and deep lymph nodes, im- age fusion between CT and sentinel node SPECT may be help- ful. The images show a typical iliac superficial sentinel node

Fig. 24.Typical late image (60 min after injection in the left leg), with several ^99mTc-nanocolloid-stained lymph nodes.

The first lymph node to appear is the sentinel. The lower image corresponds to a higher plain in scintigraphic con- trol, illustrating the state of flow of the labeling solution to the iliacal lymph nodes in the pelvis at a later time

mally on the dorsum pedis after amputation of the second toe in a case with ALM. Figure 28 shows a patent-blue-labeled SLN in the inguinal basin in a patient with malignant melanoma of the foot.

A small, easily portable, gamma probe device and the results of labeling a malignant melanoma on the back and the regional lymph nodes are demonstrated in Figs. 29±33b.

Fig. 34a and b demonstrate the excision of a blue stained and a brownish unstained SLN in an- other case. In Fig. 35a±c partly labeled (c: focally

blue stained) partly unlabeled enlarged metastatic lymph nodes are shown.

Cytological, Histopathological,

and Immunohistochemical Investigations of the SLN(s) for Metastasis of Malignant Melanomas

J

Technique of Lymph Node Investigation Various general points must be observed:

·

Small lymph nodes <5 mm in maximal thickness can be cut into two halves for paraffin embedding.

Fig. 25.Solid sentinel lymph node metastasis in pelvic site in a case with malignant melanoma of the leg (Skip-metas- tasis?)

Figs. 26±28. These illustrations were kindly made available to us by Dr. Kretschmer, Department of Dermatology, Uni- versity Clinic of Gættingen

Fig. 26.Injection of patent blue solution strongly intrader- mally in a case with extensive acrolenticular malignant mel- anoma (ALM) of the planta pedis.

Fig. 27. Injection of blue dye solution subcutaneously into dorsum pedis for SLN-labeling. A blue-stained inguinal node is seen (:) and an unstained lymph node located on the right side (*) (Fig. 28)

Fig. 28. Patent blue-labeled SLN in the inguinal basin in a case of malignant melanoma of the foot. To the right of the stained lymph node an unstained, slightly prominent lymph node can be seen located in the fatty tissue (see *)

·

Nodes that are larger, but still 7 mm in maximal thickness, should be cut into two outside slices and a middle slice.

·

All larger nodes should also be cut into slices, the number depending on their thickness, with none of the slices thicker than 2 mm, or upto a maximum of 3 mm.

Every cut surface can be used for imprint cytology.

In Giemsa stainings the intracellular melanoma pigment can be seen as greenish-brown coloration.

In other smears immunohistochemical stainings for S100 protein and HMB45 can be performed.

This additional imprint cytology and the possible immunohistochemical stainings are helpful as they can give information on the superficial layer of the node slices; after paraffin embedding and initial cutting procedures (which are necessary to obtain the whole surface of the sections used for investi- gations) the superficial parts are lost.

The thickness of the slices differs from one pathology laboratory to another. In some, slices little more than 1 mm thick are taken and at least five slices of each node. (This is the policy fol- lowed by Professor Wagner in Augsburg, Germany, for example.) However, it is clear that special tech- niques are needed to cut such thin slices from the nodes.

According to Wagner's procedure the five slices are brought in one block and at least five sections of each block are obtained. Nonetheless, there are

many other laboratories in which the principles listed above are practiced and serial sections are taken from every portion of the node at intervals of about 50 lm. This means about 50 sections from every slice. These sections are alternately stained with HE and by immunohistochemical techniques, at present with the aid of immunohis- tochemical staining machines.

At this juncture it must be pointed out that these investigations, which are needed when the SLN concept is to be applied, require high staffing levels for performance of the staining and of the examinations. The procedures can hardly be per- formed in institutes where the levels of investment are low in terms of personnel and of finance for equipment. Therefore, health policy must be changed to take account of such modern and ex- tremely important advances in medical treatment strategies.

Accumulating Experiences in Sentinel Node Detection in Malignant Melanomas 355

Figs. 29±35.Figures donated by Dr. Brodersen, Chief, Hann- over, Dermatological Surgical Unit of the Medical Faculty, Hannover, illustrating a small, easily portable, gamma probe device and the results of labeling the area of a malignant melanoma on the back and the regional lymph nodes Fig. 29.A new, very good and compact gamma probe device that is suitable for daily use in a practice (Navigator GPS)

Fig. 30.Cutaneous malignant melanoma on the back over the medial margin of the shoulder blade with localization (x) of a subcutaneous lymph node in a paravertebral site above the primary. Note the clearly detectable discoloration of the pro- minent malignant melanoma (nodal type).

Note the subcutaneous lymph node (marked by cross) sited medially above the tumor, which may be an in transit metas- tasis.

A pigmented benign seborrhoic verruca is seen to the side of the melanoma at the same level