[Soft tissue myoepithelioma, a rare tumor. A case report]

Myoepithelioma of soft tissues is a rare and under-recognized tumor. We report a case of a myoepithelioma arising in the soft tissue of the wrist in a 37-year-old man. This 3cm, nodular, well circumscribed tumor consisted of a mixture of spindle and epithelioid cells in a fibrous or focally myxoid stroma. Nuclear atypia were mild and mitotic activity was 1 mitotic figure per 10 high-power fields. No tubular epithelial structure was found. The tumoral cells expressed cytokeratin (KL1) and S-100 protein. Smooth muscle actin and desmin were negative. The excision was complete. At 5 months, no recurrence was noted. Myoepithelioma of deep soft tissue has a predilection for extremity involvement. It has to be differentiated from extraskeletal myxoid chondrosarcoma, parachordoma and synovial sarcoma. Most of myoepitheliomas are benign. However, metastasis may occur in a minority of cases.