Hyperammonemic encephalopathy in Multiple Myeloma

To the Editor: We report the development of hyperammonemic encephalopathy in a patient with multiple myeloma. A 43-year-old woman with stage IIIA light-chain multiple myeloma presented to the hospital with lethargy and a left molar mass. She had not received chemotherapy during the four months before admission. On physical examination, the patient was alert, oriented, and afebrile, with a left-sided upper molar mass measuring 5 by 6 cm. Electrolyte, blood urea nitrogen, creatinine, and calcium levels were unremarkable. Biopsy of the left molar mass revealed a plasmacytoma. The patient became increasingly confused during her hospital course. Computed tomography (CT) and . . .