Extramedullary Solitary Plasmacytoma of the Sphenoid Sinus: Radiological Evaluation and Review of the Literature

Extramedullary plasmacytomas are solitary focus plasma cell neoplasms arising in extraosseous tissues. Although the diagnosis of plasmacytomas requires evidence of no underlying multiple myeloma, these tumors can be an early presentation of, or progress to, multiple myeloma. They are infrequent tumors with no specific imaging findings, and are often initially misdiagnosed as other tumor entities. The correct diagnosis requires certain histopathologic and hematologic criteria to be fulfilled. In this case report we present a 74-year-old woman without known history of malignancy, with radiological evidence of a mass in the sphenoid sinus, extending to the clivus and the cavernous sinus on both sides, and entrapping both internal carotid arteries. The sphenoid sinus tumor proved to be an extramedullary focus of plasma cell tumor and the patient was subsequently diagnosed with multiple myeloma.