Cytomorphology of giant cell tumor of tendon sheath. A report of two cases.

BACKGROUND: Giant cell tumor of tendon sheath (GCTTS), also known as localized nodular tenosynovitis, is a benign neoplasm that occurs principally on the digits. The cytomorphologic features of this lesion on fine needle aspiration (FNA) have not been fully characterized.

CASES: In case 1, a 23-year-old female presented with a circumscribed soft tissue swelling in the left second toe. In case 2, a 16-year-old female presented with a tender swelling at the base of the right great toe. FNA smears in both instances were highly cellular, with mononuclear cells predominating and interspersed binucleated and multinucleated osteoclastlike giant cells along with hemosiderin-laden macrophages.

CONCLUSION: When interpreted along with clinical data, the diagnosis of GCTTS can usually be made with certainty using FNA cytology.