Dialysis‐Dependent Renal Failure as the Initial Presentation of Multiple Myeloma: A Case of Systematic Plasma Cell Dyscrasia Workup in Unexplained Acute Kidney Injury

Renal failure is a well‐recognized complication of multiple myeloma (MM), occurring in approximately 50% of patients at diagnosis. However, dialysis‐dependent renal failure as the dominant presenting feature of newly diagnosed MM remains uncommon, affecting only 2%–4% of patients, and poses distinct diagnostic and therapeutic challenges. A 73‐year‐old woman with no prior history of kidney disease presented with altered mental status and was found to have a creatinine of 20.29 mg/dL, hemoglobin of 5.2 g/dL, and free kappa light chains exceeding 3000 mg/dL. Neuroimaging obtained during workup incidentally revealed extensive lytic skull lesions, further consolidating clinical suspicion for MM. Serum protein electrophoresis confirmed IgA kappa monoclonal gammopathy. The patient was diagnosed with MM complicated by uremic encephalopathy and started on hemodialysis and MM‐directed therapy. Her mental status improved significantly after two dialysis sessions. Here, we discuss the importance of including MM in the differential diagnosis of any unexplained acute renal failure, the diagnostic value of incidental neuroimaging findings, and the potential for renal recovery with bortezomib‐based therapy in the setting of myeloma‐related cast nephropathy.