Plasma cell tumors of the skull base: four case reports and literature review.

Four patients (mean age, 46 years; range, 28 to 60) with skull base plasmacytomas are presented along with a review of the literature examining the progression of anterior and central skull base plasma cell tumors to multiple myeloma. The primary sites were the nasopharynx, orbital roof, sphenoid, and clivus. Three patients presented with extensive local spread of tumor. Two patients were diagnosed with multiple myeloma and treated with chemotherapy. Patients with an isolated plasmacytoma were treated with external beam radiation. A partial or complete response to therapy was seen in all four cases. Skull base plasma cell tumors are uncommon with only a limited number of published reports. Previous literature demonstrates that nasopharyngeal extramedullary plasmacytomas have a lower rate of progression to multiple myeloma than other sites. Patients with clivus, sphenoid, and petrous apex-based plasma cell tumors appear to have a higher risk of developing multiple myeloma than patients with plasma cell tumors involving the nasopharynx.