Giant Cell Tumor of the Peroneus Brevis Tendon Sheath

INTRODUCTION: Giant cell tumor of the tendon sheath is most commonly found in the flexor aspect of hand and wrist and is rare in the foot and ankle. CASE REPORT: A 49-year-old lady noticed a right lateral foot mass for 10 years. Magnetic resonance imaging suggested that the mass is originated from the peroneal tendons. The mass was excised and intra-operative findings showed that the tumor came from the peroneus brevis tendon sheath. Histological study confirmed the diagnosis of giant cell tumor. CONCLUSION: Giant cell tumor, although rare, should be one of the differential diagnoses of tendon sheath tumor of the foot and ankle.