Case studySynchronous autoimmune pancreatitis and infiltrating pancreatic ductal adenocarcinoma: case report and review of the literature
Introduction
Autoimmune pancreatitis (AIP), also known as lymphoplasmacytic sclerosing pancreatitis, is a rare form of chronic pancreatitis characterized by a mixed inflammatory infiltrate centered around the pancreatic ducts accompanied by an obliterative venulitis, acinar atrophy, and interstitial fibrosis [1]. Originally described by Sarles et al [2] in 1961 as “primary inflammatory sclerosis of the pancreas,” the term autoimmune pancreatitis was introduced by Yoshida et al [3] in 1995. AIP typically affects middle-aged patients who lack the risk factors associated with chronic pancreatitis [4]. AIP can occur in isolation or in association with other autoimmune diseases including rheumatoid arthritis, Sjögren's syndrome, primary biliary cirrhosis, primary sclerosing cholangitis, and inflammatory bowel disease [4].
The clinical presentation of AIP can vary widely. Most patients present with jaundice or abdominal pain [5]. Radiographically, the classic appearance of AIP on computed tomography (CT) scan consists of diffuse enlargement of the pancreas with effacement of the usual lobular appearance of the pancreas and a low attenuation capsule-like rim [6]. Endoscopic retrograde cholangiopancreatography classically reveals diffuse irregular narrowing of the main pancreatic duct [6]. The hallmark of this disease process is a periductal lymphoplasmacytic infiltrate found on histologic examination of the specimen. Many of the inflammatory cells are plasma cells that express IgG4, and patients with AIP often have elevated serum IgG4 levels (>135 mg/dL) [7].
The clinical presentation and radiographic appearance of AIP can mimic infiltrating pancreatic ductal adenocarcinoma [1], [4]. Traditionally, differentiation from a neoplasm has been made by examination of pathologic specimens after surgical resection [8]. Recently, there have been a growing number of reports of AIP treated with systemic steroids as definitive therapy [9], [10], [11]. These patients were identified through a combination of imaging studies, biopsy specimens, and laboratory abnormalities (elevated serum IgG4 levels). Some investigators have argued that all patients with a pancreatic lesion should undergo serum IgG4 testing and that those with an elevated serum IgG4 level should be initially treated with steroids [9], [11]. These authors argue that patients who respond to steroids can potentially be spared the morbidity associated with pancreatic resection, typically pancreaticoduodenectomy. Here, we report the rare case of a patient with histologically proven synchronous AIP and infiltrating pancreatic ductal adenocarcinoma. This case highlights the need for heightened vigilance when opting to manage AIP patients without surgical resection.
Section snippets
Case report
The patient was an 80-year-old white man in good health who developed obstructive jaundice. CT imaging revealed a dilated biliary tree and a strictured pancreatic duct, without evidence of discrete pancreatic mass. Endoscopic retrograde cholangiopancreatography was unsuccessful in traversing the biliary obstruction, and the patient required a percutaneous transhepatic biliary stent for palliation of his jaundice. The patient underwent a pylorus preserving pancreaticoduodenectomy with an
Pathology findings
Gross inspection of the resected pancreaticoduodenectomy specimen revealed a diffusely enlarged and firm pancreas, with effacement of the overall lobular architecture. The intrapancreatic bile and the main pancreatic ducts were diffusely narrowed. Histologically, the pancreas was remarkable for an intense mixed inflammatory cell infiltrate centered on the pancreatic ducts (Fig. 1A). The inflammatory infiltrate was predominantly composed of lymphocytes and plasma cells, with occasional
Discussion
Because AIP can mimic pancreatic ductal adenocarcinoma and is increasingly diagnosed it can present a diagnostic and management dilemma. Clinicians must try to balance the potential risk of missing the diagnosis of a life-threatening disease against symptom control and the desire to avoid unnecessary surgery. These risks are all the more important in the face of effective treatment of AIP with corticosteroids in many cases.
Several groups have proposed criteria to distinguish AIP from pancreatic
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