Giant Cell Tumor of the Tendon Sheath: A Rare Case of Big Toe Involvement.

Giant cell tumor of the tendon sheath (GCT-TS) is a benign yet locally aggressive proliferative lesion arising from the synovium of tendon sheaths, bursae, or joints. It most commonly affects the hands and feet, with toe involvement being particularly rare. We present a case of a 41-year-old male with a painful, firm mass on the big toe, initially suspected to be gout. Imaging studies, which included an MRI, revealed a well-defined soft tissue mass with marked cortical erosion of the first metatarsal, and histopathological examination confirmed the diagnosis of GCT-TS. The patient underwent marginal excision of the lesion, with no recurrence at follow-up. This case highlights the diagnostic challenges associated with GCT-TS in uncommon locations and highlights the utilization of MRI in assessing tumor extent and guiding preoperative planning. Despite its benign nature, the risk of recurrence necessitates complete excision and careful postoperative monitoring. The emergence of molecular therapies, such as CSF1R inhibitors, shows promise for recurrent or inoperable cases. Early recognition, precise surgical intervention, and a multidisciplinary approach in tackling this tumor are crucial for optimizing outcomes and preventing recurrence in atypical presentations of GCT-TS.