<unk>  is a rare soft tissue sarcoma arising from mesenchymal tissue and characterized by epithelioid-like features. It accounts for less than 1% of all soft tissue sarcomas. It was first clearly characterized by F.M. Enzinger in 1970. It commonly presents itself in the distal limbs (fingers, hands, forearms, or feet) of young adults as a small, soft mass or a series of bumps. A proximal version has also been described, frequently occurring in the upper extremities. Rare cases have been reported in the pelvis, vulva, penis, and spine. Histologically,<unk>  forms nodules with central necrosis surrounded by bland, polygonal cells with eosinophilic cytoplasm and peripheral spindling.<unk> s typically express vimentin, cytokeratins, epithelial membrane antigen, and CD34, whereas they are usually negative for S100, desmin, and FLI1 (FLI-1). They typically stain positive for CA125.<unk>  most commonly strikes young adults, yet no age group is immune. The disease has a tendency to develop local recurrences and metastasis thereafter to regional lymph nodes, lung, bone, brain, and other locations, including the scalp. Generally speaking,<unk>  has a high rate of relapse after initial treatment and tends to recur locally (at or near the original tumor site).<unk>  also demonstrates lymphatic spread (in 22-48% of cases), and metastasis (in 21-63% of cases). These events, as well as advanced stage (progression) and grade (aggressiveness), are predictive of an overall worse outcome. The overall five-year survival rate for<unk>  is anywhere from 25 to 78%. Importantly, the 10-year and 15-year survival rate drops off significantly. Associated with a more positive outcome are younger age, female vs. male sex, distal vs. proximal location, smaller tumor size, and negative margins upon tumor resection.
Epithelioid sarcoma
Angiomatoid fibrous histiocytoma
Alveolar soft part sarcoma
Sclerosing epithelioid fibrosarcoma
Undifferentiated pleomorphic sarcoma
Mast cell sarcoma
Hemangiosarcoma
Adenomatoid tumor