Epithelioid Sarcoma: An overview with emphasis on its differentiation from morphologic mimics

Abstract

Epithelioid sarcoma (ES) is a malignant mesenchymal neoplasm that exhibits epithelioid cytomorphology and a predominantly epithelial phenotype. The principal types based on histopathological features and location; include the classic or conventional type (CES) and the proximal type (PES). The aim of the study was to analyze our cases of ES regarding clinical, pathological and immunohistochemical features.This is a retrospective study. Seven cases of ES were included in the study. Clinical and pathological details were retrieved from patient records. Details like site, size, histopathological type and IHC features of the tumors were studied. Out of seven, five were PES and two were CES. There were six males and one female; with age ranging from 12 to 68 years. Total five tumors involved extremities. One was noted at a rare site, paratesticular region. Three tumors were larger than 5 cm in greatest dimension. On immunohistochemistry (IHC), all the tumors were reactive for CK, EMA, Vimentin, Ca 125 and showed loss of nuclear expression of INI1. CD 34 was expressed in 6 out of 7 cases.ES is a rare aggressive malignant tumor with dismal prognosis. It is often misdiagnosed because of nonspecific clinical features at presentation. Helpful clues in diagnosis are tumors in young males with epithelioid and/or spindle cell morphology, Rhabdoid cells and granuloma like central necrosis. Co-expression of epithelial and mesenchymal markers along with reactivity for CD34 and Ca 125 and loss on INI1 expression on IHC substantiate the diagnosis of ES.