Giant Cell Tumor of Soft Tissue

Giant cell tumors of soft tissue present as multilobulated masses in the skin or subcutaneous tissue, most commonly appearing on the trunk, upper extremities, and proximal aspect of the lower extremities. Similar to giant cell tumors of bone, GCTSTs grossly appear as brown, well-circumscribed, fleshy masses that microscopically consist of large multinucleated giant cells in a background of spindle cells and histiocytes. Extravasated red blood cells and hemosiderin are common findings. Mitotic figures also can be present, but necrosis and cellular atypia are not characteristic of this lesion.