Clin J Gastroenterol (2013) 6:329–333 DOI 10.1007/s12328-013-0392-z
A case of focal autoimmune pancreatitis (AIP) mimicking an intraductal papillary mucinous neoplasm (IPMN) So Nakaji • Nobuto Hirata • Hiroyuki Fujii • Kosuke Iwaki • Toshiyasu Shiratori • Masayoshi Kobayashi • Satoshi Wakasugi Eiji Ishii • Hiroyuki Takeyama • Kazuei Hoshi
Received: 5 April 2013 / Accepted: 17 May 2013 / Published online: 1 June 2013 Ó Springer Japan 2013
Abstract The present case involved a 76-year-old man with a cystic mass in the head of his pancreas. The cystic lesion, which measured 17.7 9 9.8 mm, was first detected by ultrasonography (US) at the age of 72 years. Follow-up endoscopic ultrasonography (EUS) performed at 4 years after the lesion had first been detected revealed a mural nodule measuring 14.0 9 8.4 mm in the cyst. Endoscopic retrograde pancreatography (ERP) imaging revealed that the main pancreatic duct was in communication with the cyst and that there was no irregular narrowing of the main pancreatic duct. On the basis of these results, the patient was diagnosed with an intraductal papillary mucinous neoplasm (IPMN), and stomach-preserving pancreaticoduodenectomy was performed. A histopathological examination revealed that the interior of the cystic part of the lesion was lined by a pancreatic ductal epithelium. A pathological examination of the nodular lesion detected storiform fibrosis, severe lymphoplasmacytic infiltration, and hyperplasia in the pancreatic duct epithelium together with a small amount of mucus. On immunohistological staining, the infiltrating lymphoplasmacytes were found to be positive for IgG4. Accordingly, the patient was diagnosed with focal autoimmune pancreatitis (AIP). In conclusion, we reported a case of focal AIP mimicking IPMN. This case showed neither enlargement of the pancreas nor irregular narrowing of the main pancreatic duct.
Keywords Autoimmune pancreatitis Pancreatic cyst Intraductal papillary mucinous neoplasm
Introduction Autoimmune pancreatitis (AIP) is a pancreatic disorder of presumed autoimmune etiology. It is sometimes associated with other disorders including cholangitis, salivary gland disorders, retroperitoneal fibrosis, and tubulointerstitial disease. As AIP has gained increasing worldwide recognition, many cases have recently been reported from various countries. The typical imaging findings of AIP include enlargement of the pancreas and irregular narrowing of the main pancreatic duct. AIP is a benign condition, and glucocorticoid treatment is very effective against it; however, surgical therapy is sometimes selected, especially in cases of focal or segmental AIP due to the difficulty of distinguishing AIP from other solid pancreatic masses on imaging examinations. On the other hand, there are few reports about AIP associated with pancreatic cysts. Here, we report a relatively rare case of focal AIP mimicking an intraductal papillary mucinous neoplasm (IPMN).
Case report S. Nakaji (&) N. Hirata H. Fujii K. Iwaki T. Shiratori M. Kobayashi S. Wakasugi E. Ishii Department of Gastroenterology, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba, Japan e-mail: [email protected]
H. Takeyama K. Hoshi Department of Anatomic Pathology, Kameda Medical Center, Kamogawa, Japan
The present case involved a 76-year-old male patient with a cystic mass in the head of his pancreas. The cystic lesion, which measured 17.7 9 9.8 mm, was first detected by ultrasonography (US) at the age of 72 years. Subsequently, short interval surveillance was performed with endoscopic ultrasonography (EUS), computed tomography (CT), and/ or magnetic resonance imaging (MRI) every 3 months. He
did not exhibit any symptoms during the follow-up period and had no relevant medical or family history. He only drank alcohol occasionally, and a physical examination did not detect any jaundice or abdominal/back pain. His laboratory test results on admission were as follows: hemoglobin: 12.4 g/dL (normal range: 13.5–17.5 g/dL), leukocyte count: 4.7 9 109/L (3.5–9.8 9 109/L), platelet count: 1610 9 109/L (1300–3700 9 109/L), total bilirubin: 0.5 mg/dL (0.2–1.0 mg/dL), direct bilirubin: 0.02 mg/dL (0.0–0.4 mg/dL), aspartate aminotransferase (AST): 20 U/L (13–33 U/L), alanine aminotransferase (ALT): 13 U/L (8–42 U/L), alkaline phosphatase (ALP): 190 U/L (115–360 U/L), lactate dehydrogenase (LDH): 160 U/L (119–229 U/L), amylase: 81 U/L (37–125 U/L), blood
Fig. 1 EUS detected a mural nodule measuring 14.0 9 8.4 mm in the cyst in the head of the pancreas
Clin J Gastroenterol (2013) 6:329–333
urea nitrogen (BUN): 12 mg/dL (8–22 mg/dL), creatinine: 0.7 mg/dL (0.6–1.2 mg/dL), carcinoembryonic antigen (CEA): 1.4 ng/mL (0–5 ng/mL), and carbohydrate-associated antigen 19-9 (CA 19-9): 4.8 U/mL (0–37 U/mL). His IgG4 and IgG levels were not examined. Follow-up EUS performed 4 years after the lesion had first been detected revealed a mural nodule measuring 14.0 9 8.4 mm in the pancreatic cyst (Fig. 1), which had not been detected during previous examinations. The patient’s contrast-enhanced MRI findings were as follows: the irregular mass in the head of the pancreas displayed high signal intensity on T2weighted images (Fig. 2a), the mural nodule in the cyst exhibited weak contrast enhancement, and the lower common bile duct had been constricted by the cystic lesion (Fig. 2b); however, the pancreas was not enlarged. Subsequently, endoscopic retrograde pancreatography (ERP) was carried out to evaluate whether the cystic lesion was in communication with the main pancreatic duct, and to obtain pancreatic juice for a cytological examination. ERP imaging produced the following results: the main pancreatic duct was slightly in communication with the cyst, and there was no irregular narrowing of the main pancreatic duct (Fig. 3). The obtained pancreatic juice did not contain any carcinoma cells. On the basis of these results, the patient was diagnosed with IPMN, and stomach-preserving pancreaticoduodenectomy was performed. A pancreatogram of the resected specimen clearly demonstrated that the irregularly shaped cystic lesion was in communication with the main pancreatic duct (Fig. 4). A gross examination of the specimen revealed a nodular lesion of 12 9 7 mm in size in the lobulated cystic lesion. A histopathological examination found the interior of the cyst was lined by a pancreatic ductal epithelium. A
Fig. 2 T2-weighted MRI (a transverse section, b coronal section) showing the irregular cystic mass in the head of the pancreas, and the lower common bile duct had been constricted by the cystic lesion (b)
Clin J Gastroenterol (2013) 6:329–333
Fig. 3 ERP image showing that the main pancreatic duct was slightly in communication with the cyst and the absence of irregular narrowing of the main pancreatic duct
pathological study of the nodular lesion detected storiform fibrosis, severe lymphoplasmacytic infiltration, and hyperplasia in the pancreatic duct epithelium together with a small amount of mucus. These findings were not only observed in and around the nodular lesion, but were also present along the peripheral pancreatic duct and in parts of the parenchyma in the pancreatic head. Lymphoplasmacytic infiltration was also seen around the common bile duct; however, it was not observed in the neck of the pancreas. Immunohistological staining demonstrated that the infiltrating lymphoplasmacytes were positive for IgG4 (Fig. 5) and that the patient’s IgG4?/IgG? plasma cell ratio was 65.6 %. Accordingly, the patient was diagnosed with focal AIP. His postoperative serum IgG4 and IgG concentrations were 1260 mg/dL (4.8–105 mg/dL) and 3186 mg/dL (607–1879 mg/dL), respectively. Postoperative fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET)/CT did not detect any abnormal uptake including in the residual pancreas.
Fig. 4 Pancreatogram of the resected specimen confirming that the irregularly shaped cystic lesion (arrows) was in communication with the main pancreatic duct
In 1961, Sarles et al.  first described AIP as hypergammaglobulinemia-associated chronic pancreatitis combined with lymphocytic infiltration and fibrosis. At present, diagnostic criteria for AIP have been proposed by several groups including the Japanese Pancreas Society, an expert group from Korea , and the Mayo Clinic in the United States . It is important that AIP is considered during the differential diagnosis of patients that present with symptoms related to the pancreas and biliary tract. However, in the present case we did not initially suspect AIP because of the absence of its characteristic features, i.e., enlargement of the pancreas and irregular narrowing of the main pancreatic duct, on radiological images. If we had realized that the patient had elevated serum IgG4 levels, we might have been able to treat him with glucocorticoids instead of surgery. There are a few reported cases [4–11] of pancreatic cystic lesions associated with AIP. These cases can be divided into two types based on the characteristics of their cystic lesions: pseudocysts [4–10] and IPMN . In the present case, the cystic part of the lesion was not a pseudocyst because it was lined by a pancreatic ductal epithelium. However, it also differed from an IPMN in the following respects: the absence of hyperplasia from the pancreatic ductal epithelium lining the cystic part of the lesion, the low level of mucus production, and the fact that the hyperplastic pancreatic duct epithelium in the nodular lesion was barely positive for p53 or Ki-67 on immunohistological staining. Therefore, we concluded that this case represented a third type of AIP-associated cystic lesion. It was presumed that the cystic part of the lesion had
Clin J Gastroenterol (2013) 6:329–333
Fig. 5 Loupe view of the resected specimen showing the mural nodule in the cyst (a). A histopathological examination revealed fibrosis and severe lymphoplasmacytic infiltration (b 94, c 940).
Immunohistological staining demonstrated that the infiltrating lymphoplasmacytes were positive for IgG4 (d 409)
been produced by the dilation of peripheral pancreatic ducts without neoplastic changes due to storiform fibrosis, which had resulted in severe local lymphoplasmacytic infiltration. This would explain the unique imaging findings obtained in the present case. However, it is unclear why hyperplasia developed in the pancreatic duct epithelium in the nodular lesion. In conclusion, we reported a case of focal AIP mimicking an IPMN. This case did not exhibit the characteristic features of AIP; i.e., enlargement of the pancreas and irregular narrowing of the main pancreatic duct, on radiological images. In such cases, it might be useful to evaluate the patient’s serum IgG4 levels.
Conflict of interest of interest.
The authors declare that they have no conflict
References 1. Sarles H, Sarles JC, Muratore R, Guien C. Chronic inflammatory sclerosis of the pancreas: an autonomous pancreatic disease? Am J Dig Dis. 1961;6:688–98. 2. Kwon S, Kim MH, Choi EK. The diagnostic criteria for autoimmune chronic pancreatitis: it is time to make a consensus. Pancreas. 2007;34:279–86. 3. Chari ST, Smyrk TC, Levy MJ, Topazian MD, Takahashi N, Zhang L, et al. Diagnosis of autoimmune pancreatitis: the Mayo Clinic experience. Clin Gastroenterol Hepatol. 2006;4:1010–6.
Clin J Gastroenterol (2013) 6:329–333 4. Nishimura T, Masaoka T, Suzuki H, Aiura K, Nagata H, Ishii H. Autoimmune pancreatitis with pseudocysts. J Gastroenterol. 2004;39:1005–10. 5. Muraki T, Hamano H, Ochi Y, Arakura N, Takayama M, Komatsu K, et al. Corticosteroid-responsive pancreatic cyst found in autoimmune pancreatitis. J Gastroenterol. 2005;40:761–6. 6. Welsch T, Kleeff J, Esposito I, Bu¨chler MW, Friess H. Autoimmune pancreatitis associated with a large pancreatic pseudocyst. World J Gastroenterol. 2006;12:5904–6. 7. Kamisawa T, Anjiki H, Egawa N. Rapid disappearance of a pancreatic cyst after steroid therapy in a patient with autoimmune pancreatitis. Clin Gastroenterol Hepatol. 2008;6:e33–4. 8. Nakazawa T, Ohara H, Sano H, Ando T, Imai H, Takada H, et al. Difficulty in diagnosing autoimmune pancreatitis by imaging findings. Gastrointest Endosc. 2007;65:99–108.
333 9. Sohn JW, Cho CM, Jung MK, Park SY, Jeon SW. A case of autoimmune pancreatitis manifested by a pseudocyst and IgG4associated cholangitis. Gut Liver. 2012;6:132–5. 10. Kawakami H, Kuwatani M, Shinada K, Yamato H, Hirano S, Kondo S, et al. Autoimmune pancreatitis associated with hemorrhagic pseudocysts: a case report and literature review. Intern Med. 2008;47:603–8. 11. Naitoh I, Nakazawa T, Notohara K, Miyabe K, Hayashi K, Shimizu S, et al. Intraductal papillary mucinous neoplasm associated with autoimmune pancreatitis. Pancreas. 2013;42:552–4.