A 37-year-old female presented with a history of epigastric pain of 8 weeks duration. The pain had an intensity of 7/10 and was a burning type of pain with no reference or radiation. She stated that for the previous 2 weeks her pain was aggravated by food intake. She denied any alarming symptoms in the form of loss of appetite and weight loss. There was no history of vomiting or melena. Her clinical examination was normal 

Evaluation: Her hemoglobin levels were 14 g/dl. She had a normal leukocyte count, and liver function and renal function were normal. Serum lipase and amylase levels were not elevated. An ultrasound of her abdomen did not indicate the presence of gallstones and all other organs were normal. She underwent upper gastrointestinal (GI) endoscopy to rule out a gastric ulcer due to the pain being aggravated by food. An upper gastroscopic examination revealed normal esophagus. There was 5 cm × 4 cm bulge in the antral portion of her stomach, and the overlying mucosa was erythematosus [Figure 1]. The fundus and body of the stomach were normal. There was no evidence of duodenal ulcer or growth. A biopsy from the antral portion revealed chronic gastritis, but there was no evidence of Helicobacter pylori. 

She underwent endoscopic ultrasound (EUS) due to the nodular lesion. The EUS showed a round intramural (subepithelial) lesion in the antrum of the stomach. The lesion was hypoechoic and seemed to appear from the submucosa and measured 30 mm in diameter. The outer endoscopic borders were well-defined. The EUS did not show any lymph nodes in the vicinity, and the liver was normal. The differential diagnosis of gastrointestinal tumor (GIST) was considered and fine needle aspiration was performed after color Doppler imaging ruled out the presence of vascular structures along the needle track. However, the microscopic examination  showed no evidence of malignancy and immune cytochemistry for K-ras was negative for GIST. 

Abdominal computerized tomography confirmed that apart from a submucosal lesion in the pylorus of the stomach all other organs were normal on imaging. As a result of the mass lesion in the stomach, the patient underwent partial gastrectomy determine the nature of this gastric lesion as fine needle aspiration had not clearly identified the lesion. The microscopic examination of the resected portion identified islands of pancreatic acini and ducts in the muscularis propria of the stomach. Several dilated ducts were seen extending through all the layers of the muscularis propria. There was evidence of fibrotic reaction and scant mixed inflammatory infiltrate was observed in the area. There was no evidence of malignancy and the immunocytochemistry CA19-9 was positive in the tissue while CK20 chromogranin was negative in the specimen. The overall microscopic features were consistent with pancreatic rest and GIST was ruled out.(Fig 2) The patient had an uneventful postoperative course and was discharged home after 6 days of hospitalization. She was prescribed oral proton pump inhibitors 20 mg once daily for 1-month duration only. The patient, who did not take any medication for this complaint after the initial proton pump inhibitors, is now pain-free. She has been followed up by the clinic for the last 2 years.

Further reading : 

   The  pancreatic rest, is an uncommon congenital anomaly .The incidence in autopsy series varies from 1 to  2% (range 0.55 to 13%). Such  tissue may occur throughout the gastrointestinal  tract but has a propensity to affect the stomach and the proximal small intestine. Histological features of acinar formation, development of  ducts and independent blood supply are usually present . Accordingly four types have been described ,type I having more resemblance to normal pancreatic tissue  and type IV showing only islets cells .  Although  cause of pancreatic rest remains unclear, several theories, including the ‘theory of metaplasia,’ the ‘theory of misplacement’ and the latest addition, the ‘theory of abnormalities of notch signaling’, have been proposed to explain the pathogenesis and occurrence of pancreatic heterotopia. While  majority of patients with pancreatic ectopic tissue  are asymptomatic, a variety of symptoms are attributed to this ectopic tissue . Depending upon location and bulk of the pancreatic rest the symptoms may include  , gastrointestinal bleeding, gastric outlet obstruction, gastric ulceration, pancreatitis and even obstructive jaundice, when located near Ampulla of vater  have been described .There are reports when such lesions have presented with acute perforation , what may reflect pancreatitis of stomach and duodenum . When discovered during  endoscopic  examination it is very important to differentiate these lesions from submucosal tumors and appropriate surgery may be required to confirm the lesion when results of fine needle aspiration are inconclusive .Despite the advent of novel diagnostic modalities, including endoscopic ultrasonography (EUS), computer tomography (CT) and even EUS-guided fine-needle aspiration (EUS-FNA), the differentiation from a neoplasm at times  remains a clinical challenge . When in a given case  FNAC has proved it to be  pancreatic rest and the patient is asymptomatic , such lesions can be monitored . Endoscopic features of this rare entity and a brief review is presented in this report .