IgG4-associated idiopathic tubulointerstitial nephritis complicating autoimmune pancreatitis

Abstract

1Department of Internal Medicine and 2Department of Pathology, Kurobe City Hospital, Kurobe, Japan It has been well documented that autoimmune pancreatitis (AIP) [1], also known as sclerosing pancreatitis [2], is frequently associated with fibrosclerotic diseases, such as Sjögren's syndrome [3,4], primary biliary cirrhosis [5], primary sclerosing cholangitis [3–5] or retroperitoneal fibrosis [6]. However, as yet, there have been no reports on renal complications of AIP, except for hydronephrosis, caused by retroperitoneal fibrosis. Recently, Hamano et al. [2] reported that the pathogenesis of sclerosing pancreatitis is closely related to the presence of immunoglobulin (Ig) G4. We describe here a patient with AIP in association with tubulointerstitial nephritis (TIN), which is strongly suspected to be induced by immune complexes containing IgG4. In 1992, a 66-year-old male was admitted to the surgical department of our hospital because of obstructive jaundice. He gave no history of severe abdominal pains or alcohol abuse. Computed tomography (CT) showed the diffuse enlargement of the pancreas with dilatation of the main pancreatic duct, in its body and tail, and mild dilatation of the common bile duct. Neither calcifications nor cysts were observed in the pancreas. Based on a strong suspicion of pancreatic carcinoma, the patient underwent an operation. However, the procedure was changed to cholecystectomy and choledochojejunostomy, because an intraoperative biopsy demonstrated only chronic inflammation featuring diffuse lymphoplasmacytic infiltrations with lymph follicles and marked interstitial fibrosis with acinar atrophy. At the time the patient was without urinary abnormalities, but had an elevation of the gamma globulin fraction to 22.7% (normal: 10.8–19.6%) and a positive serum antinuclear antibody (ANA) test with a titre of 1:640 and a homogeneous pattern. Serum complement levels were not measured.