S1678 Gastric Ectopic Pancreas With Pseudocyst Formation Causing Gastric Outlet Obstruction

Abstract

Introduction: Ectopic pancreas (EP) is a rare entity referring to the presence of pancreatic tissue at an anatomic location distinct from the pancreas which is commonly asymptomatic and found incidentally. EP can become symptomatic due to similar pathologic changes found in the anatomic pancreas including pancreatitis, bleeding, or pseudocyst formation. Gastric EP lesions present a diagnostic challenge as they lack distinguishing imaging and endoscopic features from other types of gastric submucosal tumors. This case report describes a rare case of EP presenting as a gastric antral mass with a unique combination of complications: chronic pancreatitis and pseudocyst formation causing gastric outlet obstruction. Case Description/Methods: A 59-year-old man presented to the hospital with nausea, vomiting, weight loss, and epigastric pain for 5 days. Exam was notable for epigastric tenderness, and labs were unremarkable. Computed tomography (CT) and index upper endoscopy showed a 4.4 x 3.5 cm multiloculated cystic mass in the gastric antrum (Figure). Endoscopic ultrasound (EUS) showed that the lesion originated from the submucosa, and fine needle aspiration (FNA) demonstrated histiocytes and epithelial cells with a high amylase level. On repeat endoscopy, interval growth of the cystic gastric mass was observed, and repeat CT abdomen/pelvis again showed the mass now with multiple cystic collections causing mass effect on a distended stomach suggesting gastric outlet obstruction. The lesion was surgically resected and determined to be EP with histologic changes of chronic pancreatitis and multiple pseudocysts. Patient did well after surgical resection and had no recurrence on repeat upper endoscopy. Discussion: EP can occur anywhere in the GI tract but most commonly are found in the duodenum or stomach. Symptoms are associated with the location, size, and pathology of the tissue. Lesions greater than 1.5 cm are more likely to be symptomatic with non-specific symptoms such as epigastric pain, abdominal fullness, nausea, diarrhea or melena. Diagnosis can be challenging, and in this case, multiple diagnostic modalities (imaging, endoscopy, EUS with FNA biopsy and surgical resection) were needed to reach a definitive diagnosis. EP is often found incidentally, and the combination of pseudocyst formation and gastric outlet obstruction in this case has been rarely reported in the literature. Prompt recognition of ectopic pancreas can facilitate the management of these complications.Figure 1.: A: Computed tomography of abdomen and pelvis from initial presentation, showing a multiloculated cystic mass (noted by *) and thickening of the gastric antral wall. B: Esophagogastroduodenoscopy (EGD) image showing a submucosal mass in the gastric antrum. C: Endoscopic ultrasound of gastric antrum with multicystic lesion appearing to originate from the submucosa.