epithelioid sarcoma (MONDO_0017387) is an aggressive malignant neoplasm of uncertain differentiation, characterized by the presence of epithelioid cells forming nodular patterns. The nodules often undergo central necrosis, resulting in a pseudogranulomatous growth pattern. It usually occurs in young adults. The most common sites of involvement are the extremities (distal-type epithelioid sarcoma), and less frequently the pelvis, perineum, and genital organs (proximal-type epithelioid sarcoma). Also known as: ES, epithelioid cell sarcoma.