Sclerosing Epithelioid Fibrosarcoma: A Study of 16 Cases and Confirmation of a Clinicopathologically Distinct Tumor

Sclerosing epithelioid fibrosarcoma (SEF) is an uncommon tumor of deep soft tissues, originally described in 1995 by Meis–Kindblom et al. In the current study, the authors identified 16 cases of SEF in the pathology files of their institutions and studied their pathologic features and disease course. The group consisted of six male and 10 female patients (age range, 14–55 years; mean age, 40 years), and the tumors were located in a limb or limb girdle (n = 7), base of the penis (n = 1), back or chest wall (n = 3), and head and neck (n = 5). Tumor size ranged from 3.7 to 22 cm (mean, 8.9 cm). Histologically, the SEFs were composed predominantly of small to moderate-size round to ovoid, relatively uniform cells, often with clear cytoplasm, embedded in a hyalinized fibrous stroma. The only consistent immunohistochemical finding was a strong, diffuse reactivity of tumor cells for vimentin. Ultrastructural analysis performed in eight cases confirmed their fibroblastic nature. Bone invasion and tumor necrosis, features not reported before, were found in six cases each. Treatment consisted of intralesional excision (n = 2), attempted wide local excision (n = 11), and amputation (n = 3), with either adjuvant radiation therapy (n = 9) or chemotherapy (n = 3). Follow-up of at least 1 year in 14 cases revealed persistent disease or local recurrence in seven patients (50%), and distant metastasis in 12 patients (86%). Eight patients (57%) died of disease 16 to 86 months after diagnosis. Five patients were alive with disease as of last follow-up. SEF shares some pathologic features with two other fibrosing fibrosarcomas, low-grade fibromyxoid sarcoma and hyalinizing spindle cell tumor with giant rosettes, but in the authors' experience behaves clinically as a fully malignant sarcoma.