Human papillomavirus-related multiphenotypic sinonasal carcinoma: a clinico-pathological dilemma case report.

Human papillomavirus (HPV)-related multiphenotypic sinonasal carcinoma (HMSC), is a new entity that is restricted to the sinonasal tract and is associated with high-risk HPV. This tumor is suggested to have an indolent behavior with a better prognosis than other carcinomas. We report a unique case of HMSC with a locally aggressive behavior. It is about a 61-year-old men presented with 12 months of unilateral progressive olfactory dysfunction accompanied by exophthalmia of the left eye, declining vision and headaches for 6 months. Computed tomography imaging revealed a voluminous mass occupying the ethmoid, maxillary and frontal sinus with bony destruction of the left ethmoidal blade. Histology showed a tumor composed of variably sized nests, separated by thick mucoid stroma. Tumor cells are plasmacytoid with hyperchromatic nuclei and frequent mitoses. Immunohistochemistry revealed that these cells were positive for cytokeratin AE1/AE3, p16 and negative for CK7, CK20, CD117, p40, p63, S100, synaptophysin and chromogranin.