Suprasellar Plasmacytoma Leading to the Diagnosis of Multiple Myeloma

Plasmacytomas are a collection of plasma cells that occur as a solitary lesion or in conjunction with multiple myeloma. Intracranial location is uncommon but should be considered as management differs. Plasmacytomas in the suprasellar region are rare but should be considered in the differential diagnosis of suprasellar masses. Clinical presentation and imaging findings have similarities and overlap between pituitary adenomas and plasmacytomas, so the diagnosis depends on biopsy and pathological evaluation. Immunohistological staining is often necessary due to structural similarities to adenomas. Isolated cases may be treated with radiation alone and surgery is reserved for symptoms due to mass effect. Systemic therapy is given if there is evidence of multiple myeloma. In this case report, we present a 52-year-old male who presented with worsening blurry vision associated with headaches and epistaxis of four months duration. CT of the head showed a large mass involving the sella and skull base. Labs showed normal calcium, creatinine, and intact pituitary function. Biopsy of the mass was initially diagnosed as a pituitary adenoma but repeat pathology revealed plasmacytoma. Body imaging revealed diffuse lytic lesions. Bone marrow biopsy and serum electrophoresis were consistent with a diagnosis of multiple myeloma. The patient underwent radiation therapy to the suprasellar mass followed by systemic therapy for multiple myeloma with bortezomib, lenalidomide, and dexamethasone. The patient achieved a very good partial response.