Case review of lgG4-related disease patient with combined tubulointerstitial nephritis and membranous nephropathy coexisting with cholangiocarcinoma: Case report

Immunoglobulin G4-related disease (IgG4-RD) has recently been recognized as an autoimmune disorder involving multiple organs. The kidney is a represented organ with a wide range of renal manifestations. The authors report a case of an 83-year-old Thai male with combined IgG4 tubulointerstitial nephritis and membranous nephropathy coexisting with cholangiocarcinoma. The patient presented with proteinuria, acute renal failure, eosinophilia, hypocomplementemia, and high serum IgG4 concentration. The diagnosis was IgG 4-related tubulointerstitial nephritis and membranous nephropathy on renal biopsy, with negative immunohistochemistry for anti-phospholipase A2 receptor antibodies. Magnetic resonance imaging (MRI) abdomen showed two wedge shaped arterial enhancing lesions of liver. Liver biopsy revealed adenocarcinoma, compatible with cholangiocarcinoma. Proteinuria and renal failure were resolved with initial steroid treatment. Meanwhile, IgG4-related membranous nephropathy should be considered in the differential diagnosis for patients with proteinuria. Potentially, IgG4-RD may be rarely associated with carcinoma development. However, further studies are recommended to ratify and confirm the association between IgG4- RD and incidence of malignancies.