Maxillary Sarcomatoid Carcinoma with Rhabdo-Myosarcomatous Dedifferentiation: a Clinic-Pathological Emphasis.

Spindle cell carcinoma or sarcomatoid carcinoma (SC) has been recently defined as a monoclonal dedifferentiated form of conventional squamous cell carcinoma (SCC) and termed as spindle cell (sarcomatoid) squamous carcinoma as per the current World Health Organization (WHO) classification. Although the frequency of SC of the breast, larynx, esophagus, and lungs has been reported, the frequency of oral SC with rhabdo-myosarcomatous dedifferentiation of the maxilla is unknown yet because of the less number of reported cases. Microscopic features of spindle cell carcinoma resemble many benign and malignant oral lesions. Therefore, a careful depiction with the help of routine hematoxylin and eosin along with immunohistochemistry using appropriate markers is necessary to diagnose spindle cell carcinoma. SC is itself a rare entity accounting for <1% of SCC; however, rhabdo-myosarcomatous dedifferentiation is exceptional; therefore, our aim is to highlight this extremely rare entity. This article focuses on SC with rhabdo-myosarcomatous dedifferentiation; other than rhabdomyosarcoma, with an emphasis on strategies to resolve the diagnostic dilemmas these tumors may present.