OBJECTIVETo study the clinicopathologic features, immunophenotype and differential diagnosis of sclerosing epithelioid fibrosarcoma (SEF).

METHODSEight cases of SEF were investigated by light microscopy and immunohistochemistry.

RESULTSThere were five males and three females. Clinically, most patients presented as a slowly growing mass. Six tumors were located in the extremities or limb girdles, and two in the trunk. Grossly, most lesions were relatively well-circumscribed with a nodular or lobulated appearance. They ranged from 2.0 to 10.5 cm in size (mean 6 cm). On sectioning, they had a gray-whitish cut surface and were firm in consistency. Microscopically, the tumors were composed of uniformly round or polygonal epithelioid cells with clear to eosinophilic cytoplasm. The tumor cells were arranged predominantly in single strands or cords and embedded in a heavily hyalinized matrix. In some areas, nests, sheets, acini or alveolar structures were also noted. Nuclei atypia and brisk mitotic activity was not evident. The mitotic count measured less than 1 per 10 high power fields. However in two cases, focal areas exhibited increased cellularity, nuclei atypia and higher mitotic activity, resembling conventional fibrosarcoma. Immunohistochemically, the tumor cells showed diffuse and strong positivity for vimentin and focal or weak positivity for EMA. There was no expression for AE1/AE3, S-100 protein, HMB45, alpha-SMA, MSA, desmin, CD34, bcl-2, CD30 and LCA. Follow-up information in six patients revealed local recurrence in 3 cases and lung metastasis in 1 case.

CONCLUSIONSSEF is a rare variant of fibrosarcoma. Despite the relatively bland appearance and low mitotic activity, the tumor is capable of local recurrence and distant metastasis. Thus, it should be considered and treated as a low to intermediate grade sarcoma. SEF needs to be differentiated from a variety of benign or malignant tumors exhibiting epithelioid features and sclerotic stromal response.