Histology: This tongue mass is a polypoid proliferation of atypical spindled cells. The mucosa overlying the tumor is ulcerated, but the adjacent squamous mucosa exhibits verrucoid dysplastic changes. The spindled cells are overtly malignant with nuclear pleomorphism, an elevated mitotic rate, and atypical mitoses. Immunostains showed that the tumor was negative for p40, AE1/AE3, and Cam5.2.

Discussion: In the mucosal head and neck, a malignant spindle cell neoplasm should be considered a sarcomatoid carcinoma (spindle cell variant of squamous cell carcinoma) until proven otherwise. Confirming the diagnosis of sarcomatoid carcinoma relies on demonstrating epithelial differentiation. This can be done by immunohistochemistry, but many examples of sarcomatoid carcinoma (like this one) are completely negative for epithelial markers. Confirming epithelial differentiation can also be done by finding areas of conventional squamous cell carcinoma within the tumor, or areas of dysplasia/carcinoma-in-situ of the adjacent, intact epithelium. Despite their poorly differentiated appearances, sarcomatoid carcinomas actually tend to have relatively good prognoses; this is likely because they grow in an exophytic fashion and therefore tend to be low-stage.