Giant Cell Tumor of Flexor Pollicis Longus Tendon Sheath: An Uncommon Case Report and Literature Review

INTRODUCTION: Giant cell tumors of tendon sheath are benign, rarely malignant, soft-tissue tumors arising from tenosynovial sheath and periarticular soft tissue. They usually present as painless masses with some restriction of movement. Histopathological diagnosis is gold standard although pre-operative fine-needle aspiration cytology (FNAC), plain radiographs, and MRI help in narrowing down the differentials. Giant cell tumor of the tendon sheath (GCTTS) although benign is notorious for having a high rate of recurrences, with most important risk factors being adjacency to joint and incomplete excision. Adequate marginal excision forms the mainstay for managing these tumors. Adjuvant radiotherapy has found some role in treating and decreasing the chances of recurrences. CASE REPORT: A 55-year-old lady was brought to the outpatient department with a history of painless, gradually progressive swelling on volar aspect of thumb. Swelling was well defined with a smooth surface. Overlying skin showed no signs of local inflammation or adherence. Pain radiographs showed soft-tissue shadow with some articular bony erosions. A ultrasound-guided FNAC and MRI showed a picture of GCTTS. An excisional biopsy was done and confirmed the diagnosis. CONCLUSION: GCTTS is a benign entity with a slow course of evolution, although uncommon, and should be kept as differential for swellings of hand and feet. Complete excision with no evidence residual tumor is diagnostic as well as curative. A regular follow-up is essential on account of high rates of recurrences.