1378 Diagnostic Dilemma: Evaluation of an Exophytic Paragastric Mass

Abstract

INTRODUCTION: Ectopic pancreas is rare congenital entity that is usually asymptomatic, appearing as an upper gastrointestinal (UGI) mass and difficult to diagnose. Our case describes a presentation of ectopic pancreas with atypical imaging and endoscopic findings. CASE DESCRIPTION/METHODS: A 28 year old male with asthma presented with hematemesis and epigastric pain. Laboratory studies included normal lipase level. Computerized Tomography (CT) of the abdomen revealed a hypervascular soft tissue mass between the pylorus and gallbladder, possibly arising from the pylorus (Figure 1). The mass was noted on prior imaging but had increased in size with a new surrounding complex fluid collection. Magnetic Resonance Angiogram (MRA) showed the mass to be contiguous with the gastric antrum and more suggestive of a vascular mass. Upper endoscopy showed esophagitis but no gastric or duodenal lesions. Hypervascularity and increase in size raised concern for malignancy. A subsequent endoscopic ultrasound (EUS) revealed abnormal tissue between the gallbladder and stomach (Figure 2). Fine need aspirate (FNA) demonstrated pancreatic acini consistent with pancreatic tissue (Figure 3). This established the diagnosis of ectopic pancreas. Patient was discharged with plans for surveillance imaging in three months. DISCUSSION: We present a case of an exophytic paragastric ectopic pancreas. Ectopic pancreas is a rare anatomical abnormality where pancreatic tissue originates outside its typical location with no anatomical or vascular connection to the pancreas. It has been reported most commonly as a submucosal lesion in the gastric antrum, duodenum or proximal jejunum. It is difficult to identify because patients are usually asymptomatic. For our patient, location near the gastric antrum was typical of ectopic pancreas. However, the exophytic appearance, lack of submucosal gastric lesion on endoscopy, paragastric location between the gallbladder and stomach, and lack of gastric invasion was atypical which made the diagnosis challenging. There are limited reports of ectopic pancreas, and it can be difficult to differentiate from malignancy. Our case highlights an atypical presentation of ectopic pancreas and the diagnostic challenges in its identification. A combination of imaging with contrast CT or MRI, and EUS with FNA will help differentiate from other lesions such as GIST. Though a rare entity, clinicians and gastroenterologists should consider ectopic pancreas in the differential diagnosis of extra-luminal UGI lesions.