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. 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.
Lesions contain balloon cells, with small pyknotic nuclei and granular or vacuolated cytoplasm.
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. The benign pigmented lesions of the eyelids do not require any medical therapy. However, any benign lesion that affects vision should be excised with primary reconstruction.