Multiple separated giant cell tumors of the tendon sheath in a thumb.

Giant cell tumor of the tendon sheath (GCTTS) is a relatively common soft tissue tumor of the hand. This tumor usually occurs as a solitary mass in a finger; simultaneous multicentric lesions in the hand are very rare. We report a 33-year-old male patient who had 2 separate GCTTS that developed simultaneously in the same thumb. The 2, rapidly growing, separated subcutaneous masses had developed on the volar aspect of the left thumb at the level of the distal phalanx and metacarpophalangeal (MP) joint. The masses were firm and mildly tender in nature. The imaging studies including magnetic resonance imaging revealed completely separated nodular masses located between the subcutaneous fat and the flexor tendon of the thumb. The preoperative tentative diagnosis was GCTTS; the masses were ablated completely by the surgery. The final pathologic diagnosis was GCTTS localized form.