A Rare Epithelioid Sarcoma of the Jaw Mimicking Pleomorphic Rhabdomyosarcoma: Case Report and Literature Review

Abstract

Abstract Background Epithelioid sarcoma, a rare soft tissue malignancy, is clinically aggressive and commonly affects distal extremities. Proximal, fibroma-like, and angiomatoid variants are lightly outlined. The proximal variant is the most aggressive, composed of larger cells and rhabdoid features, characteristically captivating one’s attention to rhabdomyosarcoma. We present a rare epithelioid sarcoma that histologically mimicked pleomorphic rhabdomyosarcoma of jaw in a 31-year-old male. Objectives To discuss histopathological features of epithelioid sarcoma of rhabdoid features, distinguishing it from other histological mimics like rhabdomyosarcoma. Methods A 31-year-old male was admitted at Muhimbili National Hospital in October 2017 with a 4-month history of slow-growing tender ulcer on the lower right jaw and right-side facial swelling. Clinical impression was squamous cell carcinoma with differential of adenocarcinoma. Various laboratory investigations, imaging, routine staining, and immunohistochemistry were performed. Results CT scan revealed a heterogenous mass in the right submandibular region. Initial examination from incision biopsy showed large oval pleomorphic tumor cells with enlarged vesicular nuclei and abnormal mitoses. Wide excision biopsy followed after conclusion of poorly differentiated carcinoma. Its examination revealed a diffuse, nodular tumor with large, polygonal, round, spindle cells displaying abundant deeply eosinophilic cytoplasm, sometimes showing eccentric vesicular nuclei. Rhabdoid features were observed. Immunohistochemistry revealed strong positivity for wide-spectrum cytokeratin, vimentin, and CD99 and was negative for EMA and myogenin. Conclusion Morphology by routine stains suggested both epithelial and mesenchymal malignancy. Cells with rhabdoid features suggested pleomorphic rhabdomyosarcoma with differential of epithelioid sarcoma. Cytokeratin, vimentin, and CD99 confirmed the diagnosis of epithelioid sarcoma, proximal variant. This case adds information on this rare entity emphasizing application of diagnostic immunohistochemistry procedures in the platform for confirmation of diagnosis to assist in proper patient management.