III.11 Irritated Nevus and Meyerson’s Nevus

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III.11.1 Definition

Benign melanocytic nevi exhibit a wide spec- trum of clinical, dermoscopic, and histopathological appearances. Most of them are histopathologically banal. There is, however, a percentage which show one or more unusual clinical features and require more attention. In- cluded among these are: (a) the irritated melanocytic nevus including the mechanically traumatized nevus with one special recently described variant, namely, the targetoid hemosiderotic nevus [1]; and (b) the UV-irradiated nevus. A special variant is (c) Meyerson’s nevus, which is surrounded by a halo of eczema in the same way that a halo of depigmentation sur- rounds a Sutton nevus [2].

Irritated Nevus

and Meyerson’s Nevus

Regina Fink-Puches, Iris Zalaudek, Rainer Hofmann-Wellenhof

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Contents

III.11.1 Definition . . . .129

III.11.2 Clinical Features . . . .129

III.11.3 Dermoscopic Criteria . . . .130

III.11.4 Relevant Clinical Differential Diagnosis . . . .130

III.11.5 Histopathology . . . .131

III.11.6 Management . . . .131

III.11.7 Case Study . . . .132

References . . . .133

III.11.2 Clinical Features

The occurrence of traumatic changes is frequent in melanocytic nevi, particularly in those that are exophytic. Mechanical irritation by clothing and shaving is probably most often responsible, but other forms of injury, such as scratching and accident, may occur. Traumatized nevi are often found in the beard area of males and axillae of females [3]. Individuals often report a sudden change of pigmentation in the nevus, especially when they did not recognize the injury. Tender- ness and itching are common symptoms. In traumatized nevus, a serocrust interspersed with hemorrhage mimicking irregular distribu- tion of pigmentation is present [4]. The surrounding skin usually is erythematous.

A variant of traumatized nevus, namely, the targetoid hemosiderotic nevus has recently been described. The main presentation is the sudden development of an asymptomatic halo on a long- lasting, acquired nevus. The nevus is always slightly exophytic or papillomatous. The nevus is surrounded by an ecchymotic, violaceous halo causing a target-like phenomenon around the central nevus [1].

The UV-irradiated nevus may exhibit increased pigmentation. The adjacent skin may show an erythema according to the skin type [5, 6].Meyerson’s nevus is characterized by the development of an eczematous halo around one ore more pigmented nevi [2, 7]. Clinical features are the appearance of an erythematous halo with overlying scales sometimes accentuated at the periphery of the erythematous zone [8]. This process can be confined to one or all nevi of an individual and may be accompanied by similar lesions not associated with nevi [9]. Slight pruri-

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III.11

tus is a clinical symptom in most lesions. The eczematous lesions become desquamative and clear spontaneously or resolve under topical therapy with corticosteroids. The nevi persist unchanged once the surrounding lesions have resolved.

III.11.3 Dermoscopic Criteria

In irritated nevus dermoscopy is helpful to differentiate blood and melanin pigmentation.

Targetoid hemosiderotic nevi show the typical features of acquired, compound melanocytic nevi with vascular–hemorrhagic changes super- imposed on the nevus and particularly surrounding it: especially irregularly sized and shaped, jet-black areas and comma-shaped ves- sels are notified. The targetoid halo demon- strates a pale, ill-defined inner area surrounded by a homogeneous reddish zone with peripheral jagged margins; however, there are no dermoscopic features specific for a hemangioma [1].

Long-term as well as short-term UV irradiation may induce several changes in the dermoscopic features of melanocytic nevi. Stanganelli et al. found an increase in pigmentation and an increased prevalence of black dots in dermoscopic images of melanocytic nevi taken during the summer months [10]. Furthermore, a higher frequency of broad and prominent pigment network structures was observed. The same authors demonstrated that after 5–13 days of intense natural sun exposure, nevi showed more black dots, brown globules, and pigment network structures [11]. Hofmann-Wellenhof et al. demonstrated that UV-irradiated nevi exhibit significantly darker pigmentation and brown-black globules show an increase in number and intensity, whereas hypopigmented areas decrease. Moreover, the pigment network becomes more faded and less prominent [5].

These changes were already observed 3 days after UV-irradiation with two minimal erythema doses (MED) [12]. Remarkably, Tronnier and colleagues demonstrated that a single erythe- matogenic UV-irradiation dose induces more effective melanoma-simulating changes than fractionally applied UV doses [13].

In Meyerson’s nevi all dermoscopic criteria of benign compound or junctional melanocytic nevi may be observed.

III.11.4 Relevant Clinical Differential Diagnosis

The clinical diagnosis of mechanically irritated nevus might be difficult. An irritated or traumatized nevus is a major simulator of melanoma, because exogenous irritation often results in changes of colors due to the effects of inflam- mation [14].

Targetoid hemosiderotic nevus should be dif- ferentiated from other pigmented lesions clinically with a peripheral halo, namely, a halo nevus, a Meyerson’s nevus, a cockade nevus, a targetoid hemosiderotic hemangioma and, most importantly, a melanoma.

A cockade nevus is a very rare variant of a melanocytic nevus characterized by a peripheral pigmented halo with an intervening non-pigmented zone [15].

Targetoid hemosiderotic hemangioma is a benign vascular lesion clinically presenting as a single, small, annular target-like lesion on the trunk or extremity of young adults [16, 17]. The lesion is composed of a brown to violaceous central papule surrounded by a thin, pale area and a peripheral ecchymotic ring, which expands and subsequently disappears, whereas the central papule persists. Targetoid hemosiderotic nevus may clinically simulate melanoma; thus, awareness of it is important to avoid unnecessary management procedures.

Ultraviolet irradiation induces transient changes in melanocytic nevi that can be detect- ed dermoscopically, leading in some cases to diagnosis of melanoma; thus, the diagnosis of melanocytic skin lesions in patients after sun exposure should be handled with care [5]. Espe- cially the increase in black-brown globules and darkening of pigmentation are often interpreted as signs of malignancy. [18–20]. In contrast, few hypopigmented areas, a faded border, and regu- larity of the pigment network are considered to be dermoscopic criteria of benign lesions [19, 21].

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III.11.5 Histopathology

Histopathological examination of irritated melanocytic nevi reveals findings that depend, in part, on the interval between irritation and excision. Acute changes, such as erosion or super- ficial ulceration, marked spongiosis, and scale crust, are well-known features of an irritated nevus [22]. The phenomenon of an increase in the number of suprabasal melanocytes after irritation of a nevus has been investigated by Tronnier et al. [14]. These melanocytes above the dermo-epidermal junction, particularly in zones beneath foci of parakeratosis or scale crusts, are mostly arranged in solitary units, but sometimes also in nests. These melanocytic nevi, which exhibit an increased number of suprabasal melanocytes, may be easily confused histopathologically with melanoma [23]; however, the observation of suprabasal melanocytes should not be equated with the diagnosis of melanoma.

Excoriated, abraded, or otherwise tormented nevi frequently display features similar to those of a persistent nevus (recurrent nevus or pseu- domelanoma) with a scar replacing the upper part of the dermis [22]. The scar is usually smaller and less prominent than in a conven- tional recurrent nevus. The “scar” or the fibro- plasia distorts the architecture of the nevus and is associated with occasional enlargement of melanocytes; therefore, an irritated or traumatized nevus is an important histopathological simulator of a regressive or of a “nevoid” melanoma [22].

Histopathologically, a central, mostly melanocytic component, and a peripheral, mainly hemorrhagic component can be observed in the fully developed stage of targetoid hemosiderotic nevus. No atypia or mitoses are found in the melanocytic component. In the papillary dermis deposits of fibrin, extravasated erythrocytes and a mixed inflammatory infiltrate intermin- gled with nests of melanocytes are observed.

The peripheral violaceous halo is histopathologically characterized by extensive hemorrhage, hemosiderin deposits, and slit-shaped dissecting vascular channels between collagen bundles [1].

After exposure to UV irradiation, melanocytic nevi may show intraepidermal features simulating melanoma in situ with solitary melanocytes disposed not only at the dermo-epidermal junction but also in the upper epidermal layers. The dermal component does not reveal any hint for malignancy and, in addition, intraepidermal melanocytes do not show atypical features [24]. The described histopathological features return to normality within a few weeks following UV irradiation.

Melanocytic nevi with eczematous halones (Meyerson’s nevi) may be either junctional or compound nevi. The pathognomonic histopathological findings are focal parakeratosis, punctuate crusts, variable amounts of spongiosis with focal microvesiculation, epidermal hy- perplasia often of the psoriasiform type, and a moderately dense inflammatory infiltrate in the papillary dermis [8]. This infiltrate is mostly perivascular and composed of lymphocytes, histiocytes, and a few eosinophils; however, there is no evidence of regression in a typical Meyerson’s nevus.

III.11.6 Management

Irritated nevi, including targetoid hemosiderotic nevi, return to normal clinical appearance 7–14 days after the initial trauma. A local anti- inflammatory therapy or therapy with local heparinoid is recommended. A major pitfall is that melanomas may also show signs of inflam- mation or irritation; therefore, if there is no change in the clinical appearance after a follow- up period of 1 month, surgical excision and sub- sequent histopathological examination is recommended.

The dermoscopic diagnosis of melanocytic skin lesions in individuals who present after extensive exposure to sun or after sunburn reac- tion should also be handled with care. Follow- up examination of these melanocytic lesions 1 month later to avoid unnecessary surgery should be done.

As a rule, in Meyerson’s nevi the inflammatory changes disappear after several months, but the melanocytic nevi persist. No further management is necessary.

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III.11.7 Case Study

A 44-year-old woman noticed a sudden change of a skin lesion on the right lower abdomen. She was very anxious about this lesion. At her first visit, she presented with a black, well-circum- scribed smooth-surfaced papule surrounded by a targetoid violaceous rim (Fig. III.11.1a).

Dermoscopically, this lesion revealed a central black area with some brownish coloration at the border of the papule. The papule was surrounded by a targetoid halo with a pale, inner area surrounded by a homogeneous reddish zone with a peripheral jagged margin. Overall the lesion appeared asymmetric in color; also, no dermoscopic structures were visible, despite the central bluish-black blotch (Fig. III.11.1b).

Upon questioning concerning a trauma, the patient remembered that one of her children had injured her at that location; thus, the diag-

nosis of an irritated nevus (targetoid hemosiderotic nevus) was made. Re-examination was recommended.

After re-examination 14 days later, clinically a well-shaped papule with a black center and brown periphery were observed. The red halo had disappeared (Fig. III.11.2a).

Dermoscopically the periphery of the lesion revealed small globules. The center of the lesion showed a well-demarcated red-black area corre- sponding to the hemorrhagic crust. The ecchymotic halo had disappeared (Fig. III.11.2b).

Comment

The clinical picture of this lesion was difficult to interpret, raising clinical suspicion of melanoma. Using dermoscopy the main structure was the central black-bluish blotch relatively sharply

Fig. III.11.1. Case Study Fig. III.11.2. Case Study

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demarcated at the periphery and surrounded by reddish color indicating hemorrhagia; however, no other dermoscopic structures were visible.

Anamnesis was helpful in this case and re-examination was recommended. After 14 days, there was no longer doubt that this was an abso- lutely benign lesion, showing symmetrical dis- tributed small globules at the periphery of the lesion.

C

Core Messages

■ Exogeneous irritation of benign melanocytic nevi may often result in clinical changes simulating irregular melanin pigmentation caused by hemorrhagic serocrusts or intralesional dermal hemorrhagia.

■ Clinically, melanoma may be simu- lated, particularly when injury has not been recognized by the patient and a sudden change of pigmentation appears.

■ In these cases, dermoscopy might be extremely helpful to differentiate between blood and melanin.

■ Targetoid hemosiderotic nevus is a clinicopathological variant of traumatized melanocytic nevus.

■ It might also clinically simulate melanoma; thus, awareness of it is important to avoid unnecessary management procedures.

■ In most UV-irradiated nevi dermoscopic appearance is still suggestive of a nevus, but in some cases the dermoscopic changes may lead to the diagnosis of melanoma.

■ Re-examination of these cases is recommended to avoid unnecessary surgical intervention.

■ Meyerson’s nevus is characterized by a halo of eczema around a nevocellular nevus. In contrast to halo nevus, no zone of depigmentation develops at any time, but the exact nature of the spongiotic process remains obscure.

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