Epithelioid sarcoma

Epithelioid sarcoma (ES) is a very rare sarcoma characterized by loss of INI1. Enzinger first described ES in 1970, but the histopathologic differential diagnosis of ES remains challenging. There are two ES subtypes, the classical type with spindle epithelioid to the central pseudogranulomatous cells, and the proximal type, which is predominantly composed of epithelioid and rhabdoid cells. ES symptoms and signs are not specific and depend on tumor localization. The only treatment for ES is radical excision with a microscope-radical margin. In general, the best treatment for ES in extremes is radical resection with a wide margin or amputation with or without lymph node dissection. Surgery may be followed by adjuvant chemotherapy and/or radiation therapy. Referral of patients with ES to a sarcoma center that offers hypofractionation RT trials and multidisciplinary clinical trials should be considered upfront. Neoadjuvant chemotherapy with ifosfamide and doxorubicin with / or without radiation therapy must be used after a multidisciplinary team discussion. On 23 January 2020, the US Food and Drug Administration (FDA) first approved tazemetostat – an inhibitor of zeste homolog 2 enhancer – therapy for metastatic ES or locally advanced ES not eligible for radical resection