Light Chain Deposition Disease and Light Chain Cast Nephropathy in a Patient With Multiple Myeloma and HIV Infection: A Case Report

Kidney dysfunction is a common complication in multiple myeloma (MM), typically presenting with cast nephropathy as a single pattern of injury on kidney biopsy and infrequently occurs in people living with human immunodeficiency virus (PLHIV). A man in his 50s, newly diagnosed with HIV, who was admitted with community-acquired pneumonia was found to have severe acute kidney injury requiring hemodialysis. Due to the lack of renal recovery, a kidney biopsy was performed, revealing fractured, periodic acid-Schiff stain-negative tubular casts with surrounding multinucleated giant cell reaction. Congo red staining was negative, but electron microscopy revealed granular subendothelial electron-dense deposits. Immunofluorescence demonstrated lambda light chain restriction. A diagnosis of light chain deposition disease with concurrent light chain cast nephropathy was made. To the best of our knowledge, this is the first description of concurrent light chain cast nephropathy and light chain deposition disease in a PLHIV and MM and highlights the importance of a kidney biopsy in the evaluation of acute kidney injury in a PLHIV and concomitant myeloma.