Cystic lesion mimicking intraductal papillary mucinous tumor arising in heterotopic pancreas of the stomach and synchronous intraductal papillary mucinous adenocarcinoma of the pancreas

A case of ectopic pancreas of the stomach accompanied by intraductal papillary mucinous neoplasm with GNAS mutation

BACKGROUND

Ectopic pancreas is basically a benign disease and is not always necessary to be removed. However, all types of neoplasms occurring in the normal pancreas such as ductal adenocarcinomas and intraductal papillary mucinous neoplasms (IPMNs) may develop even within ectopic pancreas. We recently encountered an extremely rare case of ectopic pancreas in the gastric antrum associated with IPMN possessing a GNAS mutation.

CASE PRESENTATION

A 71-year-old Japanese woman complained of epigastric pain. Computed tomography and upper gastrointestinal endoscopy showed an intramural cystic mass in the antrum of the stomach. Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) biopsy did not give a definitive diagnosis, and the patient underwent resection of the lesion. Histology of the resected specimen showed that the gastric intramural lesion was ectopic pancreas. Moreover, the lesion contained dilated duct components with tubulo-villous epithelial proliferation consistent with pancreatic IPMN. Since the covering epithelial cells had highly atypical nuclei, the lesion was diagnosed as IPMN with high grade dysplasia. Immunohistochemistry showed that the IPMN component showed to be MUC2-, MUC5AC-, and CDX2-positive but MUC1- and MUC6-negative. Mutational analyses using genomic DNA revealed that the IPMN component had a mutation of GNAS at exon 8 (Arg201Cys).

CONCLUSION

We finally diagnosed this case as gastric ectopic pancreas accompanied by intestinal type IPMN with high grade dysplasia possessing GNAS mutation. Although there were 17 cases of ectopic pancreas with IPMN including 6 cases of gastric ones reported in the English literature, this is the first case of ectopic pancreas with IPMN which was proved to have GNAS mutation. Intimate preoperative examinations including imaging analyses and EUS-FNA biopsy/cytology are recommended to decide whether the lesion has to be resected or not even if they are not effective for getting the right diagnosis.

Heterotopic Pancreas of the Gastrointestinal Tract and Associated Precursor and Cancerous Lesions: Systematic Pathologic Studies of 165 Cases

Heterotopic pancreas (HP) can be detected by accompanying symptoms or incidentally during gastrointestinal (GI) tract tumor resection. We compared clinicopathologic features among 165 resected HPs (57 gastric [35%], 56 duodenal [34%], 30 omental [18%], and 22 jejunal [13%]). Symptomatic HPs (79/135 GI tract wall HPs, 59%) were larger (P=0.05), more common in younger patients and in a gastric location (both P<0.001), and more frequently associated with lymphoid cuffs (P=0.03) than incidentally found HPs. Gastric/jejunal HPs were more frequently symptomatic (P<0.001), deeply located (P=0.03), and associated with lymphoid cuffs (P=0.008) and pancreatic intraepithelial neoplasia/intraductal papillary mucinous neoplasms (PanIN/IPMN; P=0.001) than duodenal HPs. HP was frequently associated with acinar-ductal metaplasias (117/135 GI tract wall HPs, 87%) and PanINs/IPMNs (68/135, 50%); those with PanINs/IPMNs were larger (P<0.001), more frequently located in stomach (P=0.001), had deeper wall involvement (P=0.03), and more often showed infiltrative growth (P<0.001) and lymphoid cuffs (P=0.02). Four HPs containing PanINs abutted adenocarcinomas, all expressing wild-type KRAS and intact SMAD4/DPC4 expression. Thus, symptomatic HP is associated with younger age, larger size, gastric location, and lymphoid cuffs. HPs containing PanINs/IPMNs (usually low grade) are larger and more common in stomach, have deeper wall location, and show infiltrative growth and lymphoid cuffs. Adenocarcinomas are rarely observed adjacent to HPs with PanINs/IPMNs. KRAS mutational and SMAD4/DPC4 immunohistochemical studies can discriminate between adenocarcinoma derived from HP and concurrent adenocarcinoma with HP.

Endosonogragphic features of lesions suggesting gastricectopic pancreas: experience of a single tertiary center

BACKGROUND/AIM

We aimed to present the endoscopic ultrasound (EUS) features of gastric lesions suggesting gastric ectopic pancreas during upper gastrointestinal endoscopy that were diagnosed in our gastroenterology unit, which is a tertiary center for endoscopic procedures in Turkey.

MATERIALS AND METHODS

The data of patients who underwent upper gastrointestinal EUS in our center between April 2012 and July 2014 were retrospectively analyzed.

RESULTS

All of the lesions suggesting gastric ectopic pancreas were localized in the gastric antrum. Thirty-six of 44 lesions (81.1%) showed central dimpling. Lesion borders were shown to be definite in 10 (22.7%) lesions, whereas the borders of 34 lesions (77.3%) were indefinite. Thirty-nine lesions (88.6%) had heterogeneous and 5 lesions (11.4%) had homogeneous echo patterns; whereas 29 lesions (65.9%) were hypoechoic, 9 lesions (20.5%) were hyperechoic and 6 lesions (13.6%) had mixed echogenicity. Forty-two lesions (95.5%) were shown to affect only a single sonographic layer of the gastric wall.

CONCLUSION

EUS features of lesions that strongly suggest gastric ectopic pancreas endoscopically, without any histopathological evidence and without either endoscopic or surgical resection, are as follows: indefinite border appearance, minimal heterogeneous hypoisoechoic echo pattern, existence of anechoic duct-like structures inside the lesion, common localization in the submucosal layer, and existence of umbilication.

Intraductal papillary mucinous neoplasm of the ileal heterotopic pancreas in a patient with hereditary non-polyposis colorectal cancer: A case report

We report a case of intraductal papillary mucinous neoplasm (IPMN) originating from the ileal heterotopic pancreas in a patient with hereditary non-polyposis colorectal cancer (HNPCC). A 49-year-old woman had a past history of total colectomy and total hysterectomy with bilateral salpingo-oophorectomy due to colonic adenocarcinoma and endometrial adenocarcinoma 11 years ago. Her parents died from colonic adenocarcinoma and her sister died from colonic adenocarcinoma and endometrial adenocarcinoma. The clinician found an ileal mass with necrotic change and the mass increased in size from 1.7 cm to 2.2 cm during the past 2 years on computed tomography. It was surgically resected. Microscopically, the ileal mass showed heterotopic pancreas with IPMN high grade dysplasia. Immunohistochemical staining revealed positive reactivity for MLH1/PMS2 and negative reactivity for MSH2/MSH6. This is the first report of IPMN originating from the ileal heterotopic pancreas in a patient with HNPCC in the English literature.

Heterotopic Pancreas within the Proximal Hepatic Duct, Containing Intraductal Papillary Mucinous Neoplasm

We report a unique first case of benign heterotopic pancreas arising within the proximal hepatic bile duct, containing a focus of intraductal papillary mucinous neoplasm (IPMN). The condition was diagnosed on pathological explant after left hepatic lobectomy with total extrahepatic bile duct excision.

Intraductal papillary mucinous neoplasm originating from a jejunal heterotopic pancreas: report of a case

We report a rare case of an intraductal papillary mucinous neoplasm (IPMN) originating from a jejunal heterotopic pancreas, found incidentally during surgery. A 75-year-old woman was referred to our department for surgical treatment of an abdominal aortic aneurysm (AAA) and a concurrent oropharyngeal tumor. During surgery to correct the AAA, we found a jejunal tumor incidentally and performed partial resection of the jejunum. Microscopically, the jejunal tumor showed dilated ducts containing intraluminal papillae lined with mucinous epithelium with low-grade cytological and architectural atypia within the pancreatic tissue. Immunohistochemical staining revealed MUC1 (-), MUC2 (-), MUC5AC (+), and MUC6 (-) proteins. To the best of our knowledge, only six cases of IPMN originating from a heterotopic pancreas have been reported in English, and this is the first report of an IPMN originating from a jejunal heterotopic pancreas.

Adenocarcinoma with intraductal papillary mucinous neoplasm arising in jejunal heterotopic pancreas

A 74-year-old man suffered from jejunal perforation and adhesion to sigmoid colon due to adenocarcinoma associated with intraductal papillary mucinous neoplasm (IPMN) arising in a jejunal heterotopic pancreas. The jejunal lesion showed direct extension to the sigmoid colon, which was mistaken as sigmoid colon cancer by surgeons. Malignant transformation is a rare complication of a heterotopic pancreas. About half of malignancies in reported cases were ductal adenocarcinoma arising in the stomach, and the jejunal location is extremely rare. Furthermore, IPMN is also uncommon finding in a heterotopic pancreas.