Sclerosing epithelioid fibrosarcoma

Sclerosing epithelioid fibrosarcoma (SEF) is a very rare malignant tumor of soft tissues that on microscopic examination consists of small round or ovoid neoplastic epithelioid fibroblast-like cells, i.e. cells that have features resembling both epithelioid cells and fibroblasts. In 2020, the World Health Organization classified SEF as a distinct tumor type in the category of malignant fibroblastic and myofibroblastic tumors. However, current studies have reported that low-grade fibromyxoid sarcoma (LGFMS) has many clinically and pathologically important features characteristic of SEF; these studies suggest that LGSFMS may be an early form of, and over time progress to become, a SEF. Since the World Health Organization has classified LGFMS as one of the malignant fibroblastic and myofibroblastic tumors that is distinctly different than SEF, SEF and LGFMS are here regarded as different tumor forms.

Sclerosing epithelioid fibrosarcomas are aggressive tumors that usually develop in adults and elderly individuals or, in a small minority of cases, children. SEF tumors often occur in a shoulder, hip, or lower areas of the legs and arms or, less commonly, in a vital organ or other tissue location that may be in virtually any part of the body. SEF tumors tend to recur at the site where they are surgically removed, to metastasize to other tissues, and to have poor outcomes.

Surgical resection of the primary or recurrent tumor with or without adjuvant radiation therapy has been the mainstay treatment for SEF. This treatment is often employed in order to achieve control of the tumor's local injurious effects. The sensitivity of SEF tumors to various chemotherapy regimens has been very limited. The prognosis of SEF is guarded because surgery with or without radiation therapy and chemotherapy frequently does not stop, or only stops for a short time, the progression of this disease.