Autoimmune pancreatitis associated with renal lesions mimicking metastatic tumours

Abstract

A 52-year-old previously healthy man experienced a 30-pound weight loss over 2 months. The patient was newly diagnosed with diabetes mellitus, and an abdominal ultrasound identified a pancreatic mass. Clinical history included crampy abdominal discomfort localized to the right lower quadrant, which had started 2 months earlier. No other symptoms suggestive of biliary obstruction or pancreatic insufficiency were present. Past medical history included asthma but was otherwise unremarkable, with no history of alcohol abuse or drug exposure. Findings on physical examination were normal, as were all results of initial laboratory studies, including lipase and liver enzyme levels, liver function, urinalysis results, creatinine level (66 µmol/L), levels of tumour markers (cancer antigen 19-9, carcinoembryonic antigen) and complement levels.A CT scan of the abdomen showed a bulky and heterogeneous mass in the pancreatic head, neck and uncinate (Fig. 1A), with encasement of the superior mesenteric vein (Fig. 1B). Although multiple retroperitoneal lymph nodes were identified, none was enlarged enough to fulfill the size criteria for metastasis. Three solid lesions were noted in the left kidney, with the largest measuring 1.7 cm in diameter; 3 lesions were identified in the right kidney, with the largest measuring 1.5 cm. The contrast-enhanced scans demonstrated that the lesions did not represent hyperdense cysts (Fig. 1C). A subsequent MRI confirmed the CT findings.An endoscopic ultrasound-guided fine-needle biopsy of the pancreatic mass was performed, and cytology of the aspirate revealed no malignant cells. However, we felt that the diagnosis of pancreatic cancer could not be completely ruled out, so we performed a percutaneous biopsy of the pancreatic lesion. Needle-core biopsies of the pancreas demonstrated morphology suggestive of autoimmune pancreatitis. The pancreatic tissue was almost completely replaced with fibrous tissue and an inflammatory infiltrate composed of lymphocytes and plasma cells, which were positive for IgG4 ( Fig. 2A and B). A biopsy of the duodenum revealed duodenitis with loss of mucosal villi and extensive lymphoplasmacytic and eosinophilic infiltration, which stained positive for IgG4.Laparoscopic resection was performed of one of the renal lesions, which proved to be non-neoplastic and revealed chronic tubulointerstitial nephritis with extensive interstitial fibrosis. As with the previous biopsies, there was diffuse inflammatory lymphoplasmacytic and eosinophilic infiltrate in the interstitium, which resulted in tubular obliteration ( Fig. 3A and B). No microorganisms or viral inclusions were identified. On immunochemistry there was a mixture of T and B lymphocytes; plasma cells marked uniformly for IgG and IgG4 and showed no light-chain restriction. Subsequent laboratory studies revealed elevated serum IgG and IgG4 levels. Serum electrophoresis demonstrated a slightly elevated gamma globulin level, while rheumatoid factor and antinuclear antibody levels were normal. No fresh renal tissue ...

Proposal for diagnostic criteria for IgG4-related kidney disease

“…IgG4-RKD is a new clinical entity in the field of nephrology, unrecognized before 2004, when the notion gradually emerged of it being an extrapancreatic manifestation of AIP [2][3][4][5][6][7][8][9][10][11][20][21][22][23][24][25]. This disease has many features helping to distinguish it from other types of TIN radiographically [26][27][28][29][30] and pathologically [11,21], and early detection provides the best chance for preservation of renal function because of its good responsiveness to corticosteroid therapy [2][3][4][5][6][7][8][9][10][11].…”

“…In the early reported cases, the development of renal dysfunction and/or proteinuria during the clinical course of AIP was the clue to the presence of renal involvement, and renal biopsy revealed tubulointerstitial nephritis (TIN) and fibrosis with dense infiltration of IgG4-positive plasma cells [2][3][4]. Thereafter, incidentally-detected IgG4-RKD cases in the course of close examination of AIP [5][6][7] or chronic sclerosing sialadenitis and dacryoadenitis [8] using enhanced computed tomography (CT) have been additionally accumulated. Recently, IgG4-RKD without AIP or chronic sclerosing sialadenitis and dacryoadenitis has also been reported [9][10][11].…”

Churg-Strauss Syndrome with a Clinical Condition Similar to IgG4-Related Kidney Disease: A Case Report

“…Clinical manifestations involve the pancreas, biliary tree, gallbladder, salivary glands, retroperitoneum, kidneys, lungs, and prostate. The renal lesions of patients with IgG4-related disorders are known to include tubulointerstitial nephritis or sometimes a renal pseudotumor (21,22). Takahashi et al (22) reported that 14 out of 40 AIP patients (35%) had renal involvement.…”

“…Takahashi et al (22) reported that 14 out of 40 AIP patients (35%) had renal involvement. There have been several case reports of tubulointerstitial nephritis associated with a high serum IgG4 level and almost all of these patients showed infiltration of IgG4-positive cells into the renal interstitium (21,(23)(24)(25). On the other hand, it is interesting that decreased levels of complement and membranous glomerulonephropathy have been found in some cases of interstitial nephritis associated with IgG4-related disorders (25,26).…”

Membranoproliferative Glomerulonephritis-Like Glomerular Disease and Concurrent Tubulointerstitial Nephritis Complicating IgG4-Related Autoimmune Pancreatitis

“…Renal lesions of the disease have been reported recently, most commonly they consist of tubulointerstitial nephritis (6,23,(27)(28)(29) (28,30,31). Plasma cells infiltrating the interstitium show strong immunoreactivity to IgG4 (21, 28, 30-32).…”