Fig. 6.

HPV-related multiphenotypic sinonasal carcinoma. A The tumor infiltrates as basaloid nests and strands within a myxoid stroma. Surface epithelial dysplasia is seen overlying the tumor. B Myoepithelial cell markers like SMA are positive in an abluminal pattern. C CD117 highlights tumor ducts which are often subtle on routine microscopy. D The presence of high-risk HPV required for a diagnosis of HPV-related multiphenotypic sinonasal carcinoma. In this case, it was demonstrated by RNA in situ hybridization