Adenocarcinoma with intraductal papillary mucinous neoplasm arising in a duodenal heterotopic pancreas: a case report

Adenocarcinoma developing from gastric heterotopic pancreas: a case report and short review

Heterotopic pancreas is a relatively rare condition that may be associated to clinical complaints or signs. Here, we report a case of gastric heterotopic pancreas assictaed to ductal adenocarcinoma. Obstructive jaundice was the initial symptom prompting medical intervention. A 73-year-old male patient presented with yellow staining of the skin and sclera, and dull epigastric pain. Contrast-enhanced computed tomography showed stenosis of the extrahepatic distal bile duct and mass lesions of the antrum. The patient underwent tumor resection, distal gastrectomy (Billroth II), and common bile duct exploration. Postoperative pathological examination revealed an adenocarcinoma located in the wall of the gastric antrum. Immunohistochemical results suggested that the tumor originated from the pancreas. Heterologous pancreatic tissue and a dilated pancreatic duct were found in the tumor. These findings suggest malignant transformation of the gastric heterotopic pancreas. Of note, jaundice as clinical complaint for adenocarcinoma associated to gastric heterotopic pancreas.

Gastric outlet obstruction caused by heterotopic pancreas in a patient with alcohol use disorder

INTRODUCTION AND IMPORTANCE

Heterotopic Pancreas (HP) is defined by the presence of pancreatic tissue in an anatomically distinct location from the main pancreas. While often clinically silent, it may present symptomatically. If located in the gastric antrum, HP may cause gastric outlet obstruction (GOO). The objective of this paper is to present a rare case of HP in the gastric antrum causing GOO.

CASE PRESENTATION

Herein, we report a 43-year-old man who presented with abdominal pain and non-bilious emesis in the setting of COVID-19 infection and alcohol consumption. During the initial workup, computed-tomography (CT) was non-specific but demonstrated GOO, concerning for cancer. Cold forceps biopsies taken during esophagogastroduodenoscopy (EGD) confirmed benign HP. Since the patient was symptomatic from gastric outlet compression, he underwent resection via laparoscopic distal gastrectomy and Billroth II gastrojejunostomy. At 1-month postoperative follow-up, the patient recovered uneventfully. We hypothesized that GOO by HP in this case may have been associated with cumulative effects of alcohol consumption and COVID-19 infection on the ectopic tissue.

CLINICAL DISCUSSION

HP is rare and difficult to diagnose preoperatively. When located in gastric antrum, HP can cause GOO, mimicking gastric malignancy. Combination of EGD/EUS, biopsy/FNA, and surgical resection are necessary to definitively make the diagnosis. Finally, it is important to consider that heterotopic pancreatitis or structural changes in HP may occur due to classic pancreatic stressors like alcohol and viral infections.

CONCLUSION

HP may cause GOO presenting with non-bilious emesis and abdominal pain, mistaken for malignancy on CT imaging.

Intraductal Papillary Mucinous Neoplasm Arising from Heterotopic Pancreas in Stomach: A Case Report and Review of Literature

Heterotopic pancreas is generally an asymptomatic condition which is found incidentally at surgery, endoscopy, or autopsy. Intraductal papillary mucinous neoplasm (IPMN) arising from heterotopic pancreas is extremely rare. In this study, we report a patient with IPMN arising from heterotopic pancreas. A 28-year-old man presented to our department with epigastric pain for 20 days. Physical examination revealed no abnormal findings. Computed tomography (CT) revealed an intramural cystic-solid mass on the gastric wall. Endoscopic ultrasonography (EUS) revealed a hypoechoic, heterogeneous, and multilobulated lesion with septa. Cyst fluid analysis based on EUS guided fine needle aspiration (EUS-FNA) indicated that the concentration of carcinoembryonic antigen (CEA) was 492 ng/ml. The patient received Billroth I subtotal gastrectomy, and then a 4.6 cm mass from the lesser curvature of the stomach was removed. Finally, the patient was diagnosed as IPMN with low grade dysplasia in an ectopic pancreas based on histopathological analysis. This report described the clinical, radiologic, endoscopic and histologic features of IPMN arising from heterotopic pancreas in a 28-year-old man involving the stomach. All pathologists involved in the diagnosis and clinicians involved in the treatment should be aware of this kind of tumor pattern to improve the correct identification, diagnosis and management of patients.

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.