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Benign versus Malignant Renal Masses in Autoimmune Pancreatitis Warranting the Need for Biopsy


Khan, Muhammad Ali MD; Ahmad, Usman MD; Nawras, Ali MD, FACG

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American Journal of Gastroenterology: October 2013 - Volume 108 - Issue - p S262-S263
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Purpose: Type 1 autoimmune pancreatitis (AIP) is considered to be a manifestation of a novel clinicopathological entity called IgG4-related sclerosing disease. Extrapancreatic manifestations can include involvement of bile ducts, salivary gland, lung nodules, thyroiditis, interstitial nephritis, renal masses, and retroperitoneal fibrosis. We encountered a case of AIP who also developed renal cell carcinoma (RCC). To the best of our knowledge this is the third reported occurrence of renal cell cancer associated with AIP (Table 1). We report a case of a 73-year-old Caucasian male who presented with obstructive jaundice, pruritus, a 4-month history of oily diarrhea, weight loss, and uncontrolled diabetes mellitus. Physical examination was unremarkable except for scleral icterus. Liver function tests demonstrated a total bilirubin of 16.9 mg/dL, AST of 118, ALT of 213, and alkaline phosphatase of 438. A CT scan demonstrated mild biliary tree dilatation. No definite obstructing mass or gallstone was visualized. The pancreas demonstrated no surrounding inflammatory change or ductal dilatation. A left renal mass measuring 30 mm was also noted. ERCP and EUS-FNA were performed. The radial EUS disclosed diffuse hypoechogenicity of pancreatic parenchyma with small pancreatic duct measuring 1.3 mm in size. The pancreatic head was prominent with no discrete mass identified. ERCP showed distal common bile duct stricture measuring 20 mm in length located in the region of the head of the pancreas. The stricture was brushed, biopsied, and stented. EUS-FNA was subsequently performed with biopsies taken form the head of the pancreas. The pathology was negative for malignancy. Based on endoscopic findings an IgG subclass analysis was performed resulting in an elevated IgG4 of 388 mg/dL consisted with AIP. Prednisone was initiated which led to complete resolution of his symptoms. Repeat ERCP after 2 months revealed a patent biliary tree and the stent was removed. The patient was maintained on 20 mg of prednisone. Five months into the course of treatment a repeat CT was performed to re-evaluate the renal mass, initially suspected to be an extrapancreatic manifestation of AIP. On repeat imaging the left renal mass had increased in size to 34 mm. The patient underwent partial left nephrectomy which revealed RCC. Majority of renal masses associated with AIP are benign and considered a part of the extrapancreatic manifestations of the disease. However, it is imperative to have a low threshold for suspecting RCC particularly if the mass is not responsive or increasing in size during treatment. These cases highlight the need for continued follow-up and potential biopsy or surgery.

Table 1
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