CASE REPORT Ectopic pancreatic rest in the stomach

Introduction Ectopic pancreas (EP) also known as the heterotopic pancreas, aberrant pancreas or pancreatic rest is relatively a rare development anomaly. It is defined as pancreatic tissue that lacks anatomical or vascular continuity with the pancreatic gland. EP was first described in the 18th century by Schultz but confirmed by Klob histologically a century later [1]. Misplaced pancreatic tissue during gut rotation or metaplasia of pancreatic endodermal tissue during development are among the few theories discussed at present on the origin of EP [2]. Incidence of EP at autopsy is in a wide range of 0.5 – 13.7% [3]. It is most commonly found in the stomach, duodenum and the jejunum. The rest of the gastrointestinal tract (GIT) are also possible sites [2]. Rarely EP is found in the mediastinum, lung and brain [4].


Introduction
Ectopic pancreas (EP) also known as the heterotopic pancreas, aberrant pancreas or pancreatic rest is relatively a rare development anomaly. It is defined as pancreatic tissue that lacks anatomical or vascular continuity with the pancreatic gland. EP was first described in the 18th century by Schultz but confirmed by Klob histologically a century later [1]. Misplaced pancreatic tissue during gut rotation or metaplasia of pancreatic endodermal tissue during development are among the few theories discussed at present on the origin of EP [2]. Incidence of EP at autopsy is in a wide range of 0.5 -13.7% [3]. It is most commonly found in the stomach, duodenum and the jejunum. The rest of the gastrointestinal tract (GIT) are also possible sites [2]. Rarely EP is found in the mediastinum, lung and brain [4].
Mostly asymptomatic, it may present with dyspeptic symptoms and abdominal discomfort. EP is occasionally associated with gastric outlet obstruction, GIT bleeding, pancreatitis and rarely adenocarcinoma [2,5]. Upper GI endoscopy (UGIE) would classically reveal a subepithelial lesion (SEL) with normal overlying mucosa, which would at times demonstrate a central umbilication, denoting a pancreatic duct opening. Imaging modalities like contrastenhanced CT (CECT) and MRI render limited assistance in diagnosing EP. Punch biopsy at UGIE is generally nondiagnostic, yet endoscopic ultrasound (EUS) and guided fine needle aspiration biopsy (EUS-FNAB) or core biopsy may demonstrate EP preoperatively. Surgical excision with a minimum margin is advocated for diagnosis and eliminate the premalignant potential of EP. No further problems are anticipated following complete excision.

Case presentation
Our patient was a 27-year-old male, who was previously healthy and of average built. He presented with dyspeptic  symptoms for 9 months duration without any red flag signs. He was already using proton pump inhibitors (PPI) on regular basis but his symptoms had prevailed. An UGIE showed a EP of GIT is diagnosed incidentally in the majority of cases during endoscopy or surgery for other indications [6]. The main symptom of EP is pain and is thought to be due to tissue irritation by pancreatic secretions. This patient had clinical features of gastritis and was confirmed endoscopically. Symptomatic EP should be excised. Current literature advocates excision in asymptomatic, incidentally found cases as well to avoid future complications [6].
All authors disclose no conflict of interest. The study was conducted in accordance with the ethical standards of the relevant institutional or national ethics committee and the Helsinki Declaration of 1975, as revised in 2000.
A biopsy was not attempted but an ultrasound scan (USS) and a CECT of the abdomen were planned with a working diagnosis of a Gastro-Intestinal Stromal Tumour (GIST), a common SEL. CECT showed a 1.8 x 1.7 x 1.2cm oval-shaped solid mass in the greater curvature of the stomach. The slow heterogeneous enhancing pattern was noted suggestive of a GIST, GIT schwannoma or a leiomyoma (Figure 2). EUS and MRI were unavailable.
Due to equivocal radiological data and unavailability of EUS-FNAB, surgical excision was planned. India ink was injected to the SEL, 1 week before the surgery for external identification of lesion during the procedure. Laparoscopic exploration was undertaken where a wedge resection of the dyed lesion was made. The peritoneal survey was normal otherwise. The patient had an unremarkable recovery period and was discharged on postoperative day 2. Histopathology showed unencapsulated pancreatic tissue organized into lobules comprising acini and ducts with scattered islets of Langerhan, distributed through the stomach wall ( Figure 3). No pathology was identified in the pancreatic tissue. The lesion was complete excised.

Discussion
Pathologic classification of EP was formed by Heinrich in 1909. A modification of this by Gaspar-Fuentes (1973) is currently in use (Table 1). According to the classification, this patient belongs to Type 1. Pathologies associated with the orthotopic pancreas can occur within EP as well [2,5].
The endoscopic appearances were of a benign gastric tumour. Possible diagnoses of a GIST, leiomyoma or EP can be differentiated by non-invasive methods ( Table 2). EUS and EUS-FNAB are sensitive methods of diagnosis which were unavailable for this patient. Ÿ EP is a rare developmental anomaly which is usually found incidentally.
Ÿ It is best excised to avoid complications.