Imaging Studies
Because of the metastatic potential of melanoma, any suspicious lesions, warranting a metastatic workup, encompass the use of imaging studies.
Diagnostic Procedures
Most lesions can be diagnosed by clinical appearance, and biopsies should be performed whenever a suspicion of malignancy exists.
Histologic Findings
Freckles: These demonstrate hyperpigmentation on the basal layer of the epidermis.
Lentigo simplex: These lesions show hyperpigmentation on the basal layer of the epidermis with an increased number of melanocytes.
Solar lentigo: See lentigo simplex.
Melanocytic nevi: These lesions can be classified histologically as junctional, compound, or intradermal. Junctional lesions show nests of nevus cells in the epidermis at the dermal-epidermal junction. Compound nevus is when the nests of nevus cells are dropping off into the dermis, and, on intradermal lesions, the remaining epithelial nests migrate into the dermis.
Congenital melanotic nevi: Many lesions contain features of compound nevi with nevus cells in the dermis and the dermal-epidermal junction.
Spindle-epithelioid cell nevus: Compound nevi with spindle or epithelioid cells are present throughout the epidermis and dermis. Mitotic figures and nuclear atypia are present. Histologic differentiation from malignant melanoma may be difficult to make.
Balloon cell nevus: Lesions contain balloon cells, with small pyknotic nuclei and granular or vacuolated cytoplasm.
Nevus of Ota: Pigmented dendritic melanocytes are present throughout the dermis.
Blue nevus: Pigmented dendritic melanocytes and macrophages are scattered throughout the dermis with fibrous tissue adjacent.
Malignant melanoma: Lentigo melanoma is characterized by hyperplasia of atypical melanocytes throughout the basal cell layer. Superficial spread melanoma is typified by atypical melanocytes that occur in nests throughout all levels of epidermis. In nodular melanoma, dermal invasion is always present, and it exhibits large anaplastic epithelioid cells.
Staging
Tumor depth has been the hallmark of staging in cutaneous malignant melanoma. As described by Breslow, [6] melanomas measuring 0.76 mm or less carry a 5-year survival rate of 100%, while those invading greater than 1.5 mm are associated with a 5-year survival rate of 50-60%.
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Lentigo maligna or superficial spreading melanoma of the eyelid. Courtesy of Joel Sugar, MD.
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Focal melanoma of the upper lid in a patient with history of prior excised conjunctival melanoma. Courtesy of M Duffy, MD, PhD.
