First-Onset Psychosis Leading to Multiple Myeloma Diagnosis: A Case Report and Literature Review.

Although multiple myeloma (MM) can cause various neurological complications, direct central nervous system (CNS) involvement is exceedingly uncommon and poorly understood. There has been one other reported case in the literature of a patient presenting with psychosis prior to diagnosis of MM. We present a case of a 58-year-old female with no history of psychiatric illness who presented to a behavioral health inpatient unit with paranoid delusions, multisensory hallucinations, and disorganized behavior in the days preceding her MM diagnosis. Due to hypercalcemia and altered mental status, she was transferred to an inpatient medical unit for further medical workup. Imaging revealed a sternal mass and diffuse lytic lesions. MM was confirmed. Her psychotic symptoms improved after one cycle of chemotherapy and steroids, treatment with aripiprazole, and resolution of hypercalcemia. Unlike other case reports where mental status changes have been described as consequences of already diagnosed MM, this patient's psychotic symptoms manifested prior to her MM diagnosis. While the exact pathophysiological mechanisms remain unclear, this case highlights a potential link between the sudden onset of psychosis and underlying undiagnosed MM. Healthcare providers need to be aware of this rare clinical presentation of psychosis in conjunction with MM.