Localized Tenosynovial Giant Cell Tumor Originating From the Flexor Carpi Radialis Tendon Sheath: An Unusual Case.

Tenosynovial giant cell tumor (TGCT) is a benign synovial proliferative lesion most commonly involving the digits, with wrist involvement being relatively uncommon. Occurrence from the flexor carpi radialis (FCR) tendon sheath is particularly rare and may mimic a volar ganglion cyst clinically. We report a case of a 27-year-old male presenting with a gradually enlarging, painless swelling over the volar wrist. Magnetic resonance imaging demonstrated a well-defined lesion arising from the FCR tendon sheath in close proximity to the radial artery, without osseous involvement. Complete excision was performed, and histopathology confirmed localized TGCT. The patient had an uneventful recovery, with no recurrence at one-year follow-up. This report highlights the diagnostic challenge and emphasizes the importance of imaging and complete surgical excision.