Desmoplastic melanoma of the vulva

The clinical and pathological features of a nonulcerated desmoplastic melanoma in the vulva of a 52-year-old woman are presented. Pleomorphic neoplastic spindle cells, fibroblasts and collagen formed a poorly demarcated 18 mm dermal mass. No adjacent intraepidermal component was seen. Immunoreactivity was demonstrated for S100 protein, vimentin, neuron-specific enolase and actin, but not for HMB-45, CAM 5.2, cytokeratin, epithelial membrane antigen, desmin or CD34. Electron microscopic examination was noncontributory. Treatment included a left hemivulvectomy with ipsilateral groin node dissection followed by radiotherapy. The tumor recurred six weeks later and was unresectable. The patient is alive with symptoms nine months after presentation. This is the first case report of a vulvar desmoplastic melanoma without neural involvement or an intraepidermal component. The variable tumor cytomorphology, nonspecific immunohistochemical and ultrastructural features render a diagnosis more difficult than with other primary cutaneous melanomas.