Superficial acral fibromyxoma: an overview.

Superficial acral fibromyxoma is a rare, slow-growing soft tissue tumor, which is commonly located in the periungual and subungual regions of the fingers and toes in adults. To date, fewer than 50 cases have been reported worldwide. Microscopic examination reveals a moderately circumscribed, nonencapsulated tumor situated in the dermis, which may also extend into the subcutis. The neoplasm consists of a moderately cellular proliferation of stellate and spindle-shaped fibroblast-like cells embedded in a myxocollagenous stroma. Mast cells are easily identified throughout this lesion. Multinucleated stromal cells may also be present, but nuclear atypia and mitotic figures are rare. The tumor shows immunoreactivity for CD34, epithelial membrane antigen, CD99, and less frequently, CD10. Superficial acral fibromyxoma has a benign behavior but may persist or recur if inadequately excised. Therefore, complete excision and close follow-up are advised.