case_images: PMC11796192_01
case_images: Serum monoclonal protein, urine protein creatinine Ratio (PCR) and serum albumin level over time
case_images: 12882_2025_3986_Fig2_HTML.jpg
case_images: PMC11796192_01_12882_2025_3986_Fig2_HTML.jpg
case_images: Fig1
case_images: His IgG kappa monoclonal protein level progressed over two years to 18.4 g/L in August 2021 (Fig. 1) which resulted in a bone marrow biopsy showing less than 10% plasma cells although there was a large aggregate concerning for evolving plasma cell neoplasm.
case_images: Kidney biopsy findings in histiocytic glomerulopathy withoutcrystals. Light microscopy shows segmental to global mesangial expansion by cellular component with prominent resorption droplets (A, PASx200),confirmed to be histiocytes by immunohistochemistry (B, CD163 x 100).Immunofluorescence, both direct on frozen tissue and performed on formalin fixed tissue with pronase digestion shows cytoplasmic staining within these histiocytes limited to IgG and kappa (C, kappax200; D, lambdax200). Ultrastructurally, the cytoplasm of these cells is distended with numerous electrondense granules, but no crystals (E, EMx2500; F, EMx12000)
case_images: 12882_2025_3986_Fig1_HTML.jpg
case_images: PMC11796192_01_12882_2025_3986_Fig1_HTML.jpg
case_images: Fig2
case_images: He was monitored over the next two years with stable creatinine but increasing proteinuria and proceeded to renal biopsy in November 2023 (Fig. 2).