The typical hallmarks of renal parenchyma injury associated with IgG4-related kidney diseases are fibrosis and massive infiltration of the renal interstitium with lymphocytes and IgG4-positive plasma cells.[8] Melica et al described 2 patients with human immunodeficiency virus infection and acute interstitial nephritis related to diffuse infiltration of the kidney interstitium, predominantly with CD138+ plasma cells.[9] In these 2 renal disorders, the plasma cells were positive for both κ and λ light chains, excluding malignant plasmacytic infiltration. This evidence concerns the gene SDC1 and kidney disorder.