Diagnosis by endoscopic ultrasound of a large aberrant pancreas mimicking malignant gastrointestinal stromal tumor of the stomach

Table of Contents

A 78-year-old woman was referred to our hospital complaining of dysphagia and weight loss. Gastroscopy showed a large submucosal lesion at the lesser curvature of the stomach ([Fig. 1]). Computed tomography (CT) scan revealed a large tumor at the lesser curvature of the stomach ([Fig. 2]), which was diagnosed as a gastrointestinal stromal tumor (GIST) of the stomach. However, endoscopic ultrasonography (EUS) showed a heterogeneous lesion with a small anechoic area ([Fig. 3]), which was suspected to be aberrant pancreas or malignancy. The patient was successfully treated surgically by wide excision of the lesion ([Fig. 4]). Pathological examinations confirmed a diagnosis of aberrant pancreas ([Fig. 5]).

Fig. 1 Appearance of the submucosal lesion with central umbilication at the body of the stomach. a Endoscopic view, with (b) narrow-band imaging.

Fig. 2 Computed tomography scan revealed a large submucosal lesion at the lesser curvature of the stomach (white arrow).

Fig. 3 A large submucosal mass was seen at the body of the stomach by radial endoscopic ultrasound (Olympus, Tokyo, Japan). The lesion was heterogeneous with a small anechoic area.

Fig. 4 Gross examination shows a yellow rubbery intramural mass with ill-defined borders, measuring 3.5 × 2.5 × 1.5 cm.

Fig. 5 a Lobulated pancreatic tissue occupies the submucosa. b The lesion contains a mixture of pancreatic acini, ducts, and islets.

Aberrant pancreas is defined as pancreatic tissue lying outside of its normal location and lacking anatomic or vascular connections with the pancreas. It does not usually cause symptoms and is found incidentally in the stomach, duodenum, small intestine, Meckel’s diverticulum [1], or biliary tract at upper endoscopy, upper gastrointestinal contrast radiography, laparotomy, or autopsy [2] [3]. Therefore, aberrant pancreas is not a great problem in the clinical setting. Complications of aberrant pancreas usually include inflammation with formation of an inflammatory mass, ulceration, bleeding, and obstruction, with clinical manifestations of acute and chronic pancreatitis [4].

Aberrant pancreas mimicking a malignant GIST of the stomach is extremely rare, and it is difficult to obtain adequate tissue from the lesion. The present case suggests that the finding of a large submucosal tumor of the stomach with central umbilication and heterogeneous lesions with small anechoic areas, as defined by endoscopy and EUS, could indicate suspected aberrant pancreas. If the diagnosis is uncertain, the use of aggressive techniques instead of EUS alone, including EUS-guided biopsy possibly with surgical resection, should be advocated.

Endoscopy_UCTN_Code_CCL_1AB_2AC_3AB

Endoscopy_UCTN_Code_CCL_1AF_2AD

References

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• 3 Dolan R V, ReMine W H, Dockerty M B. The fate of heterotopic pancreatic tissue: a study of 212 cases.  Arch Surg. 1974;  109 762-765
• 4 Marshall S F, Curtiss F M. Aberrant pancreas in stomach wall.  Surg Clin North Am. 1952;  32 867-875