Malignant Epithelioid Soft Tissue Tumours- A Pathologist's Perspective With Review of Literature.

Background Soft tissue tumours with epithelioid morphology have many differential diagnoses, which include epithelioid sarcoma, malignant extrarenal rhabdoid tumour, epithelioid malignant peripheral nerve sheath tumour, epithelioid leiomyosarcoma, epithelioid angiosarcoma and sclerosing epithelioid fibrosarcoma. There are other rare entities also. They often express characteristic patterns of immunohistochemical markers that can be used to identify these tumours. Materials and methods This retrospective study comprises 22 cases of malignant soft tissue tumours with epithelioid differentiation diagnosed over a period of four years. Findings regarding clinical presentation, cytological findings, histopathological findings and immunohistochemical profile of the tumours were noted and analyzed. Results A total of 22 cases were included in the study including five cases of epithelioid sarcoma (conventional and proximal), three cases of epithelioid angiosarcoma and epithelioid myxofibrosarcoma, two cases of epithelioid malignant peripheral nerve sheath tumour, epithelioid gastrointestinal stromal tumour and clear cell sarcoma each, one case of epithelioid leiomyosarcoma, sclerosing epithelioid fibrosarcoma, malignant extrarenal rhabdoid tumour, monophasic synovial sarcoma and malignant and malignant perivascular epithelioid cell tumour each. Conclusion Pathologists should be aware of the various differential diagnoses of soft tissue tumours with epithelioid morphology. Over and above the clinical findings and morphological features, ancillary methods like immunohistochemistry help to arrive at a definitive diagnosis in most cases.