Skin and Soft Tissue—Melanoma
Concept
Four main subtypes—superficial spreading, nodular, lentigo maligna, and acral lentigenous—with several spe- cial situations (anal, subungal). Work-up should be sys- tematic—establish risk factors, biopsy, stage the patient, sample lymph nodes, and then determine any adjuvant treatment. Expect questions regarding lymph node sam- pling, especially groin dissections.
Way Question May be Asked?
“52 y/o male presents to your office with a skin lesion on his leg (or arm, or abdomen, or back) that has recently changed in both color and size.” You may also be shown a picture of an obvious melanoma, or get the patient sent to you after a biopsy performed by a dermatologist.
How to Answer?
History
Changing skin lesion (A,B,C,D,E mnemonic) Bleeding lesion
Ulceration Itching
Establish Risk Factors for Melanoma
Excessive sun exposure Fair skin
+FHx
Hx of melanoma
Dysplastic nevus syndrome Xeroderma pigmentosum
Physical Exam
Examination of lesion (color, size, symmetry) Examination of regional lymph node basins
Consider the Differential
Benign nevus Seborrheic keratosis Pigmented wart Squamous cell cancer Basal cell cancer
Biopsy Lesion
If not in cosmetically sensitive place, excise with 1–2 mm margin
If large, punch bx through thickest portion of lesion or incisional bx
Always orient the specimen
If subungal, split open nail—only need diagnosis here
Staging the disease (Clark’s system has really fallen out of favor—mostly based on Breslow depth)
TNM system: I primary < 1.5 mm depth, no nodes II > 1.5 mm depth, no nodes III regional nodal disease or
in-transit mets IV distant metastases Histological staging (Breslow)
Thin 0–0.75 mm
Intermediate 0.76 to 4 mm
Thick > 4 mm (80% chance of mets)
103 Part 2.qxd 10/19/05 2:52 AM Page 103
Diagnostic Studies
CXR
CBC, LFT, LDH FNA any palpable nodes If palpable nodes:
CT scan to evaluate nodal and next nodal basin CT liver and brain
Margins of resection (will likely need to re-excise after biopsy)
5 mm for in-situ lesions 1 cm for < 1 mm depth 2 cm for > 1 mm depth
head/neck—twice the diameter of the lesion
subungal finger—split nail to biopsy, amputate distal phalanx (elective node dissection if > 0.75 mm) subungal toe—ray amputation
ear— full thickness wedge resection twice the diam- eter of the lesion
anal—local excision, APR only if pt is incontinent or has severe pain from invasion of the sphincters anterior to ear—re-excision + modified radical neck
dissection and superficial parotidectomy
Lymph Node Sampling
SLN bx should be offered to all pts with extremity and truncal primaries greater than 1 mm in depth (except subungal)
Get pre-op lymphoscintigraphy
Use combo of handheld gamma counter and Lymphazurin blue dye
Send sentinel node for frozen section
Complete node dissection if sentinel node positive Only do deep node dissection in groin if have gross
disease in apical nodes (sapheno-femoral/
Cloquet’s node) or CT shows suspicious iliac adenopathy
→Not if only microscopic disease in superficial nodes or CT suggests nodes that are positive to level of aortic bifurcation as unlikely to have any therapeutic benefit and downside of severe leg edema!
Prophylactic node dissection if:
b/w 1–4 mm and lesion overlies the primary nodal basin (parotid, inguinal, axillary)
lesion > 1 mm in head or neck Adjuvant therapy
Stage II melanomas deeper than 4 mm or Stage III disease get offered vaccine or high-dose interferon
Treatment of in transit/recurrent disease
Re-excision, local radiation, and isolated hyperther-
mic limb perfusion with melphalan and TNF has received a lot of attention recently
Treatment of Stage IV disease
Isolated mets (liver, lung, brain) should be resected assuming no other evidence of disease
Common Curveballs
Melanoma won’t be on extremity but on trunk and pre- op lymphoscintigraphy will light up several nodal basins
Lymph nodes in groin will be clinically palpable Sentinel node biopsy won’t work
Will be other melanomas if don’t do complete skin survey
Expect pulmonary/brain metastases during first several years of follow-up of your pt
Depth will be 0.74 or 0.77 mm
Pathology may turn out to be squamous cell or basal cell
There will be in-transit disease The pt will have two melanomas
Microscopic disease in Cloquet’s node—will you do deep inguinal dissection?
Management of subungal/anal melanoma
Decline in pulse ox reading during operative procedure (typical artificial side effect of blue dye)
Pt. may have allergic reaction to blue dye
Strikeouts
Not being able to justify your reasoning on doing or not doing a deep inguinal node dissection when appro- priate
Performing a shave biopsy or FNA of a suspected melanoma
Not performing physical exam to lymph node basins Not knowing difference between Clark’s levels and
Breslow depth
Not knowing re-excision margins for different depth melanomas
Not orienting the specimen for the pathologist
Not getting CT to evaluate next echelon of nodes with palpable nodes clinically
No SLN bx in head and neck, subungal and anal melanomas!
Trying to perform SLN bx when lesion overlies a lymph node basin
Trying to offer chemotherapy to pts with isolated metastases
Discussing vaccine therapy (experimental)
104 Skin and Soft Tissue—Melanoma
Part 2.qxd 10/19/05 2:52 AM Page 104
