Giant cell tumor of the flexor hallucis longus tendon sheath: a case study.

Giant cell tumor of tendon sheath is infrequently documented in the foot and even less near the ankle. This case report involves such a tumor of the flexor hallucis longus tendon presenting at the posterior ankle. Diagnosis was aided by magnetic resonance imaging, and treatment consisted of complete surgical excision. Pathologic examination verified the diagnosis of giant cell tumor of tendon sheath, and follow-up magnetic resonance imaging revealed no remnants or recurrence of tumor 1 year after surgery.