“…As ES can sometimes comprise spindle-shaped cells, malignant mimics include those of malignant spindle-cell neoplasms such as synovial sarcomas, fibrosarcomas, angiosarcomas, malignant fibrous histiocytomas, and malignant extrarenal rhabdoid tumors [11,14,18]. The proximal type of ES should also be differentiated from other neoplasms with epithelioid and/or rhabdoid cells, for example, extrarenal malignant rhabdoid tumor, melanoma, rhabdomyosarcoma, malignant peripheral nerve sheath tumor, undifferentiated carcinoma, and other sarcomas including synovial sarcoma and extraskeletal myxoid chondrosarcoma [2,3,5]. Appropriate immunohistochemical staining showing positivity for vimentin, cytokeratins, EMA, and CD34, and negativity for the S100 protein, HMB-45, FLI-1, and desmin, as well as SMARCB1/INI1 gene deletion, is helpful to arrive at an accurate diagnosis and exclude most of the aforementioned tumors [15].…”