superficial spreading melanoma

Most common of tumors that arise in melanocytes of individuals with white skin. Etiology: (risk factor) 1) presence of precursor lesions a) congenital melanocytic nevus b) dysplastic (Clark's) melanocytic nevus 2) family history of melanoma 3) light-skinned individual with inability to tan 4) excessive sun exposure, especially during preadolescence Epidemiology: 1) adults 30-50 years of age 2) slightly higher incidence in females 3) white race, rare in brown- & black-skinned individuals 4) 70% of melanomas in white persons 5) 10% arise in high-risk families 6) 90% of cases are sporadic Pathology: 1) large, atypical melanocytes throughout epidermis in multiple layers, occurring single or in nests 2) melanocytes often have regularly dispersed fine particle of melanin 3) spindle cells & small malignant melanocytes may be present 4) intra-epidermal radial growth of pigmented cells (carcinoma in-situ) 5) vertical growth of malignant cells which invade the dermis a) occurs over months to years b) potential for metastases Clinical manifestations: 1) flattened papule, becoming a uniformly elevated plaque with irregular border, expanding in diameter, then developing one or more nodules 2) dark-brown to black with admixture of pink, gray, blue-gray, violaceous hues - marked variegation & haphazard pattern 3) white areas indicate regressed areas 4) size 5 mm - 2.5 cm 5) asymmetrical lesions, irregular, sharply-defined borders 6) isolated single lesions 7) distribution: upper back (most common in men), legs (most common in women), anterior trunk, may occur in regions traditionally not exposed to sun 8) 1/2 of melanoma in blacks (rare) develop on sole of foot 9) moderately slow-growing lesion over a period of 1-2 years Diagnosis: ABCDE of diagnosis A: Asymmetry B: Border is irregular C: Color is mottled haphazard mixture of brown, black, gray, pink D: Diameter is large > 6 mm E: Enlargement and elevation of lesion Laboratory: 1) excisional biopsy with narrow margins 2) Wood's lamp may help define borders 3) epiluminescence microscopy increases diagnostic accuracy 4) punch biopsy when excisional biopsy not feasible/impractical Management: (same for nodular & acral lentiginous melanoma): 1) examine regional lymph nodes 2) surgical excisions a) melanoma in situ - excise with > 5mm margin b) thickness < 1 mm 1] excise with 10 mm margin 2] excise down to fascia or muscle if no underlying fasica 3] direct closure without graft often possible 4] node dissection only if palpable & suspscious for metastasis c) thickness 1-4 mm 1] excision with 20 mm margin 2] excise down to fascia or muscle if no underlying fasica 3] regional lymphadenectomy if sentinel node procedure is positive 4] lymph node dissection if regional lymph nodes are palpable d) thickness > 4 mm 1] excision with 30 mm margin 2] excise down to fascia or muscle if no underlying fasica 3] lymph node dissection if regional lymph nodes are palpable 3) adjuvant chemotherapy a) interferon alpha-2b b) melphalan

General

cutaneous melanoma

References

Color Atlas & Synopsis of Clinical Dermatology, Common & Serious Diseases, 3rd ed, Fitzpatrick et al, McGraw Hill, NY, 1997, pg 198-99
Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 544

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