Ancient schwannoma of the hand.

Ancient schwannoma is a schwannoma subtype, characterized by extensive degeneration and diffuse hypocellular areas. These changes are believed to occur because it takes a long time for ancient schwannomas to develop. Schwannomas with these degenerative changes can be misdiagnosed as sarcomas or other soft-tissue neoplasms. We present a case of a slowly enlarging ancient schwannoma of the thenar area in a 67-year-old woman. The differential diagnosis included atypical soft tissue sarcomas and tumors of neural origin. The combination of ultrasound and magnetic resonance imaging findings provided features that narrowed the differential diagnosis, and histology confirmed the presence of an encapsulated schwannoma with extensive myxomatous degeneration and multiple vessel thrombosis. The clinical, radiological, and histological features and the diagnostic approach of this rare entity are described.