Tenosynovial fibroma.

Tenosynovial fibroma or angiofibroma of tendon sheath is a distinctive clinicopathological entity occurring mainly in young and middle-aged men and affecting dominantly the distal extremities. Fingers, hands and wrists are the site of 80 per cent of cases. Palmar aspects of hands and plantar aspects of foot are preferentially involved. The trunk and neck are seldom affected. They are generally small, firm, sometimes painful lesions attached to tendon sheath and/or tendon. The lesion must be distinguished from a variety of benign lesions including nodular fasciitis, angiomyoma and giant-cell tumour of tendon sheath. It can also be confused with sarcoma, including synovial sarcoma, because of the presence in it of characteristic slit-like spaces which have been identified as vascular rather than synovial spaces by virtue of the Factor VIII content of their lining cells.