IgG4-Related Disease With Renal and Pulmonary Involvement.

Immunoglobulin G4-related disease (IgG4-RD) is a rare immune-mediated disease affecting multiple organs and tissues. There is often the presence of elevated serum Ig4 subtype with histological evidence of lymphoplasmacytic infiltration, fibrosis, and phlebitis. The mainstay of treatment is steroids therapy. We report the case of a 66-year-old man presenting with acute on chronic renal failure and pulmonary nodules seen on PET-CT scan. He also had elevated serum IgG4 subclass and histological features in keeping with IgG4-RD. He failed steroid therapy but responded subsequently to rituximab with complete resolution of his symptoms.