Fibroma of Tendon Sheath : Differential
Differential Diagnosis: A typical case of fibroma of tendon sheath does not present a diagnostic challenge. Cellular variants should be distinguished from fibrous histiocytoma, fibromatosis, and nodular fasciitis. The presence of cleft-like vascular spaces, circumscription and encapsulation favor fibroma. Another entity in differential diagnosis is giant cell tumor (GCT) of tendon sheath. Both arise at similar locations and share gross features. GCT is composed of round cells and has numerous multinucleated giant cells, foamy macrophages, and hemosiderin deposition. Rare cases of fibroma of tendon sheath show degenerative-type atypia and they may be mistaken for pleomorphic sarcoma. However, pleomorphic sarcomas have greater cellularity, increased mitotic activity (including abnormal forms), and more striking storiform growth pattern. The image shows a focus of myxoid change consisting of a proliferation of spindle and stellate mesenchymal cells in loose myxoid stroma.