Osteoid and bone formation in desmoplastic malignant melanoma

A 77-year-old man presented a recurrent subungual malignant melanoma with desmoplastic features in which heterotopic bone had developed. Histological, histochemical and immunohistochemical findings confirmed the diagnosis of malignant melanoma. Electron microscopic findings suggest that desmoplasia is the result of fibroblastic differentiation of spindle melanoma cells.