Abstract

Cutaneous malignant squamomelanocytic tumor is a rare entity demonstrating both malignant squamous and malignant melanocytic cells. We present a case in an 86 year old female. She presented with a lesion on her forearm of unknown duration. The lesion appeared to be a 6 mm ill-defined gray-blue papule with a background of erythema. Histologic examination demonstrated a fairly well circumscribed nodule in the dermis without a connection to the overlying epidermis. The nodule was composed of two intermingled cell types-atypical epithelioid cells with associated melanin in the cytoplasm and atypical epithelial cells with focal keratin pearl formation. Numerous mitotic figures were identified. The squamoid component was highlighted by EMA, p63, CAM5.2, and CK5/6. The pigment containing cells were highlighted by MART-1/Melan A, SOX-10, and Fontana-Masson stains. The tumor was negative for CK20, ERG, Perls iron stain, chromogranin, and synaptophysin. Final diagnosis was favored to represent a cutaneous malignant squamomelanocytic tumor. Breslow depth was 1.5 mm, but the tumor was present broadly at the base. The tumor was treated through wide local excision with sentinel lymph node biopsy, with no recurrence to date.