Rare case of anaplastic plasmacytoma in the sinonasal tract

Background: Extramedullary plasmacytomas are tumors that develop from plasma cells and rarely express anaplastic features. To our knowledge, there have only been three reported cases of anaplastic plasmacytomas of the sinonasal tract in the English literature. We detail the fourth case. Methods: A 70-year-old male was seen with a 4-month history of nasal congestion, bloody mucous, and left sided nasal obstruction. On positron emission tomography/computed tomography, the lesion was FDG-avid with an SUV_max of 25.1. A biopsy of the lesion and subsequent immunohistochemical staining confirmed the diagnosis of an anaplastic plasmacytoma. Results: The patient is undergoing a 5-week course of curative-intent radiation therapy. Conclusion: Extramedullary plasmacytomas with anaplastic features are very rare. We highlight the value of thorough histopathological review and detailed immunostains to arrive at a diagnosis of anaplastic extramedullary plasmacytoma.