A Rare Case of Acute Kidney Injury with Central Nervous System Manifestations.

Multiple myeloma (MM) is usually a disease of the elderly and only less than 1% are young individuals below 35 years of age. Central nervous system (CNS) manifestations of MM are even rarer, the most common being leptomeningeal involvement. We report a case of a 35-year-old male who presented with a fever of 3 weeks duration associated with slurring of speech, nasal regurgitation, hearing loss, and decreased urine output. CNS examination showed IX, X, and XII cranial nerve palsies with right otitis media and bilateral mastoiditis with conductive hearing loss. Renal biopsy showed cast nephropathy. The kappa-lambda ratio was 18, with β2 microglobulin measuring 12 mg/L. Bone marrow showed 90% plasma cells, and skeletal survey had bony lytic lesions. He responded well to dexamethasone, bortezomib, and thalidomide. His renal functions returned to normal, and palsies have improved completely. This report shows that MM should be suspected even in young patients with classical features of myeloma and CNS involvement is very rare in MM.