Sclerosing EpithelioidFibrosarcoma

Overview

Sclerosing epithelioid fibrosarcoma (SEF) was first described in 1995 and since then 39 cases havebeen reported. Here we describe 6 cases of SEF (3 in women and 3 in men). The patients agedfrom 22 to 79 years. The tumours were located in soft tissues of the extremities (in 3 cases in thelower, in 2 instances in the upper extremity) and of the trunk (in 1 case). The lesions werepartially nodular, of gray-white colour, and hard in consistency. Histologically, they were composed of epithelioid round to ovoid small cells with a sparse cytoplasm and a very low mitoticactivity. The tumour cells formed cords and alveoli or were scattered individually within a densehyalinized collagenous stroma. The neoplasms also contained foci of conventional fibrosarcoma,necrosis, calcification, and metaplastic bone. On immunohistochemistry, the neoplastic cells werepositive for vimentin. Two cases were immunoreactive for epithelial membrane antigen and onetumour also for cytokeratins. The proliferative activity, assessed by MIB 1 antibody (Ki-67), wasdetected in 1 -⁠ 6% of neoplastic cells in primary tumours. Follow-up information was available in 5patients. In two cases, there were local recurrences and distant metastases (in the lungs, upperextremity, and mediastinum). One of these patients died of SEF. The differential diagnosis of thisrelatively low-grade fibrosarcoma is broad and includes, along with a variety of benign and malignant soft tissue lesions, infiltrating carcinoma, and, to a lesser extent, sclerosing lymphoma.

Key words:
sclerosing epithelioid fibrosarcoma -⁠ soft tissues