Case Report

We present the case of a 53-year-old asymptomatic female patient, with no significant past medical history, who performed a screening upper endoscopy. In the lesser curvature of the proximal gastric body (4cm below the gastroesophageal junction), a 2cm subepithelial lesion was incidentally found (Fig. 1); no other relevant findings were documented.

Fig. 1. Upper endoscopy: 2cm subepithelial lesion located in the lesser curvature of the proximal gastric body (1A – front view; 1B – retrofllexed view).

Subsequently, the patient underwent an EUS that confirmed the existence of a well-defined, oval-shaped, hypoechoic homogeneous lesion, with 19.7mm, involving the deep submucosa and the muscularis propria (3^rd and ^4rd layers) of the gastric body (Fig. 2A). This lesion had an echo pattern with some vascularization (Doppler positive) (Fig. 2B). An EUS-guided fine-needle biopsy (FNB; 2 passes) using a 22g Sharkcore needle (Medtronic®) was performed (Fig. 2C).

 

Fig. 2. EUS (transgastric): well-defined, oval-shaped, hypoechoic homogeneous lesion, with 19.7mm, involving the deep submucosa and the muscularis propria (2A) and showing some vascularization (2B); EUS-FNB (2C).

What is the most likely diagnosis?

Submeter

Despite the most probable subepithelial lesions in this location and with similar EUS features are GISTs, pathology revealed fragments of pancreatic exocrine parenchyma, with groups of acinar cells (Fig. 3). Thus, the diagnosis of a gastric ectopic pancreas was established.

Fig. 3. Pathology: fragments of pancreatic exocrine parenchyma, with groups of acinar cells (3A – H&E, x10; 3B: H&E, x40).

Discussion

Ectopic pancreas (EP), also designated as heterotopic pancreas, is a rare congenital condition defined by the presence of pancreatic tissue outside its typical location without anatomic or vascular connections to the orthotopic pancreas. [1,2]

EP mainly develops in the stomach and the antrum is by far the most common location, followed by the gastric body, and the cardia. As the gastric body is the most frequent site of GISTs and schwannomas, differential diagnosis with these entities was mandatory in this patient.

EP is typically diagnosed incidentally during routine upper endoscopy and surgical explorations. Endoscopically, it appears as smooth bulge covered with normal mucosa, sometimes displaying the typical landmark of central umbilication. On EUS, it presents as a hypoechoic subepithelial lesion with indistinct borders, usually arising from the submucosa (3^rd layer). Occasionally it may involve the muscularis propria and serosa. In half of cases, an anechoic ductal structure can be seen within the lesion. [1,2]

Although EP is foremost asymptomatic, it may present with a variety of nonspecific symptoms, such as epigastric pain, nausea, and vomiting.

Complications and carcinoma developing in an ectopic pancreatic tissue are exceedingly rare. Therefore, it does not require treatment unless symptomatic, and can almost always be dismissed in the absence of symptoms. [1,2]

Yet innocent, EP may mimic other subepithelial lesions, in particular gastrointestinal stromal tumors (GISTs) or neuroendocrine tumor (NETs), which harbor malignant potential and benefit from resection. Therefore, pathological diagnosis confirmation should be sought using standard forceps biopsy (“bite on bite” technique) and, preferably, EUS-fine needle tissue acquisition. [3]

References

1. Chou JW, Cheng KS, Ting CF, Feng CL, Lin YT, Huang WH. Endosonographic features of histologically proven gastric ectopic pancreas. Gastroenterol Res Pract. 2014; 2014:160601.
2. Attwell A, Sams S, Fukami N. Diagnosis of ectopic pancreas by endoscopic ultrasound with fine-needle aspiration. World J Gastroenterol. 2015 Feb 28;21(8):2367-73.
3. Gottschalk U, ietrich CF, Jenssen C. Ectopic pancreas in the upper gastrointestinal tract: Is endosonographic diagnosis reliable? Data from the German Endoscopic Ultrasound Registry and review of the literature. Endosc Ultrasound. 2018 Jul-Aug;7(4):270-278.

Authors

Susana Marques¹, Miguel Bispo¹, Rafaela Rego², Ricardo Rio-Tinto¹, Paulo Fidalgo¹, Jacques Devière^1,2,3

1. Digestive Unit, Champalimaud Foundation, Lisbon, Portugal.
2. Pathology Department, Champalimaud Foundation, Lisbon, Portugal.
3. Department of Gastroenterology, Hepatopancreatology, and Digestive Oncology, Erasme University Hospital – Université Libre de Bruxelles, Brussels, Belgium.