Paranasal giant cell fibroblastoma: case report and immunohistochemical findings.

Few published reports describe patients with giant cell fibroblastoma, a rare, benign soft-tissue tumor that recurs locally and predominantly arises in children. A 4-year-old boy underwent surgery for removal of a giant cell fibroblastoma in the paranasal region, an unusual site. Six months after excision the tumor recurred locally. Immunohistochemical examination of the primary tumor and recurrence revealed vimentin positive staining in the cytoplasm of all the cells. The multinucleated giant cells and the flat cells bordering the vessel-like spaces were negative for Factor VIII-related antigen, S-100 protein, actin and desmin. Some histiocytes stained positively for alpha-1-antitrypsin, alpha-1-antichymotrypsin, antimacrophage and lysozyme antibodies. These immunoreactions indicate that giant cell fibroblastomas have a fibrohistiocytic origin.