Superficial acral fibromyxoma: clinical and pathological features.

Superficial acral fibromyxoma (SAFM) is a recently recognized myxoid tumor that usually occurs on the fingers and toes of middle-aged adults. We report on the typical case of a 50-year-old woman with a SAFM in the right big toenail that had been slowly growing for more than 10 years. To our knowledge, this case is the first reported case for which clinical pictures are available. Histologically, the lesion was non-encapsulated and was composed of stellate and spindle cells, arranged in a myxoid matrix. No atypia or mitotic figures were found. Neoplastic cells showed positive staining for CD34 and negative staining for epithelial membrane antigen (EMA), actin, desmin, keratins, S100 protein, CD99, and HMB45. Differential diagnosis encompasses benign and malignant myxoid and spindle cells tumors such as myxoid neurofibroma, sclerosing perineurioma, superficial angiomyxoma, and several low-grade myxoid sarcomas.