Atrial plasmacytoma and hypercalcemia.

To describe a patient with hypercalcemia due to multiple myeloma and an associated atrial plasmacytoma.A case report is presented with clinical and laboratory findings. We review the differential diagnosis of hypercalcemia and discuss multiple myeloma and plasmacytomas.A 48-year-old woman presented to the emergency department with lethargy after sustaining trauma to the head. She was found to have a subdural hematoma and a parietal intraparenchymal hemorrhage. She had a serum calcium level of 17.2 mg/dL (normal, 8.4 to 10.6), anemia, thrombocytopenia, and renal insufficiency. Serum protein electrophoresis revealed a monoclonal gammopathy, and a bone marrow biopsy specimen was consistent with multiple myeloma. The patient required surgical evacuation of her subdural hematoma. Postoperatively, multiple complications developed, including a supraventricular tachycardia. She did not regain consciousness, and ventilatory support was withdrawn. On autopsy, she was found to have disseminated myeloma and an atrial plasmacytoma.This case report emphasizes the need to consider a plasmacytoma as a manifestation of multiple myeloma when localizing symptoms are present.