Pseudotumors due to IgG4 Immune-Complex Tubulointerstitial Nephritis Associated With Autoimmune Pancreatocentric Disease

Abstract

Autoimmune pancreatitis (AIP) is a mass-forming chronic fibroinflammatory condition centered on the pancreatobiliary system and characterized by predominant immunoglobulin G4 (IgG4)-positive plasma cells. Recent reports have brought to light the multiorgan involvement of this disease. We describe a series of 5 cases of tubulointerstitial nephritis (TIN) associated with AIP and characterize the clinical, pathologic, ultrastructural, and immunopathologic features of TIN. The specimens consisted of 4 biopsies and 1 nephrectomy. The average patient age was 64 years (range 45 to 78) and the male to female ratio was 4:1. All had histologic and/or clinical and radiographic evidence of AIP, mass-forming sclerosing cholangitis, or both. The clinical impression in 4 patients was a renal mass or vasculitis. Two patients had renal insufficiency. Histologic preparations revealed a dense tubulointerstitial lymphoplasmacytic infiltrate. Eosinophils were often numerous. Tubulitis and tubular injury were present, along with tubular atrophy with focally thickened tubular basement membranes (TBMs). The histologic appearance ranged from a cellular, inflammatory pattern without tubular atrophy to a striking expansive interstitial fibrosis with tubular destruction. The nephrectomy specimen demonstrated a masslike nodular pattern of inflammation with normal renal tissue elsewhere. Glomeruli were uninvolved. By immunohistochemistry or immunofluorescence, numerous plasma cells in the infiltrate were positive for IgG4. TBM granular IgG deposits, predominantly of the IgG4 subclass, were detected in 4 of 5 cases by either immunofluorescence or immunohistochemistry. By electron microscopy, corresponding amorphous electron-dense deposits were present in the TBM in these cases. This type of TIN, typically characterized by a masslike lesion consisting of a lymphoplasmacytic infiltrate with eosinophils and prominent IgG4-positive plasma cells and immune-complex deposits in the TBM, may be part of a systemic IgG4-related disease, which we term "IgG4-associated immune complex Multiorgan Autoimmune Disease" (IMAD).

IgG4-associated cholangitis: a comparative histological and immunophenotypic study with primary sclerosing cholangitis on liver biopsy material

“…One patient (case no. 7) initially presented with multiple renal masses that on biopsy showed features of autoimmune pancreatitis-associated renal disease (this case has been reported previously 10 ). Multiple intrahepatic biliary strictures were also noted on an MRI.…”

“…In fact, these distinctive nodules resembled autoimmune pancreatitis-associated pseudotumors observed in the pancreas and in other organs. 9,10 Bile ductular reduplication and onion skin-type fibrosis were noted in both primary sclerosing cholangitis and IgG4-associated cholangitis. Significantly, there appeared to be no difference in the stage of fibrosis between the two groups.…”

Consensus statement on the pathology of IgG4-related disease

“…The three major histopathological features associated with IgG4-related disease are (Figure 1) 3,6,[8][9][10][11][12][13][14][15][16][17] (1) Dense lymphoplasmacytic infiltrate (2) Fibrosis, arranged at least focally in a storiform pattern (3) Obliterative phlebitis…”

“…2 The histopathological features bear striking similarities across the involved organs. [6][7][8][9][10][11][12][13][14][15][16] IgG4-related disease is therefore analogous to sarcoidosis, another systemic disease in which diverse organ manifestations are linked by a unique histological appearance. Disparate disorders such as Mikulicz's syndrome, Kü ttner's tumor, multifocal fibrosclerosis, and eosinophilic angiocentric fibrosis are now considered to fall within this disease spectrum.…”

American Society of Nephrology Quiz and Questionnaire 2012

“…The term IgG4-related sclerosing disease is also used for this entity because it results in a sclerosing lesion of multiple organs, including the kidney, with formation of pseudotumors (41,42). Patients with renal involvement are often elderly men presenting with progressive renal failure.…”