A Case of Extramedullary Plasmacytoma in Both Maxillary Sinuses

Plasmacytoma is a rare hematolymphoid malignancy. The three types of plasmacytoma, according to clinical features and morphological characteristics, include solitary bone plasmacytoma, extramedullary plasmacytoma (EMP), and multiple myeloma (MM). Although EMP of the head and neck region accounts for approximately 3% of all plasma cell tumors, the involvement of both paranasal sinuses is extremely rare. Herein, we describe a rare case of EMP involving both maxillary sinuses in a 73-year-old male patient who had achieved complete remission from MM following chemotherapy 2 years ago. The EMP was treated successfully with radiotherapy.