Gastric neuroendocrine tumor arising from heterotopic pancreas
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There are few English reports on secondary tumors from heterotopic pancreas. Here, we describe a case of gastric neuroendocrine tumor (NET) arising from heterotopic pancreas. A 72-year-old woman underwent esophagogastroduodenoscopy as part of a general health check-up. An endoscopic examination revealed a submucosal tumor on the greater curvature of the gastric body. Laparoscopic and endoscopic cooperative surgery was performed. Histological diagnosis concluded that it was a Grade 1 NET arising from heterotopic pancreas. We report this extremely rare case of a NET presenting as a submucosal tumor, considered to have originated from heterotopic pancreatic tissue.
KeywordsNeuroendocrine tumor Heterotopic pancreas Stomach
Neuroendocrine neoplasms of the stomach are relatively uncommon. Most neuroendocrine neoplasms are neuroendocrine tumors (NETs) that are well-differentiated, non-functioning enterochromaffin-like cell tumors arising predominantly in the corpus–fundus region. They encompass three distinct types—type I tumors are associated with autoimmune gastritis, type II tumors are associated with multiple endocrine neoplasia type 1, and type III are sporadic tumors . Most Japanese NETs are type I.
Heterotopic pancreas is the most common form of heterotopia diagnosed in the stomach. Although its pathogenesis is controversial, it may be secondary to the abnormal location of developing pancreatic buds during embryogenesis. Heterotopic pancreas is commonly situated in the submucosa of the distal stomach, most often within 5 cm of the pylorus. It is seen during endoscopy as a solitary, umbilicated submucosal lesion with occasional erosion of the overlying mucosa. Heterotopic pancreas is composed of pancreatic acini, ducts, or islets. Ectopic pancreatic tissue can undergo secondary changes such as acute pancreatitis [2, 3], pseudocyst formation , development of mucinous cysts , and pancreatic carcinoma [6, 7, 8]. Neoplasms arising from ectopic pancreas are extremely rare. There has been only one previous report of NET occurring from ectopic pancreas . Here, we report an extremely rare case of a NET presenting as a submucosal tumor, considered to have originated from ectopic pancreatic tissue.
The usual location of heterotopic pancreas is the stomach in 25–38% of cases, the duodenum in 17–35% of cases, and the jejunum in 15–21.7% of cases. It is rarely found in the esophagus and gallbladder. Gastric lesions are discovered in the antrum in 85–95% cases either on the posterior or anterior wall, being more common along the greater curvature . Many gastric NETs arise in the body or fundic mucosa; the location of the tumor in our case cannot rule out heterotopic pancreatic origin. Guillou et al.  suggested three criteria for the diagnosis of adenocarcinoma arising within the setting of heterotopic pancreas. First, they stated that the tumor must be within or near the heterotopic pancreas; second, a transition between the pancreatic tissue and the tumor should be established; and third, the non-neoplastic pancreatic tissue should show well-developed ducts and acini. As the lesion in the present case was a NET, it was difficult to meet the second criterion. However, the diagnosis of NET arising from heterotopic pancreas was reasonable because the findings were compatible with the other two criteria.
A malignancy arising from heterotopic pancreas is exceedingly rare [6, 7, 8]; however, several reports have been published. Chetty and Weinred  reported the only other case of NET occurring from ectopic pancreas. Their case was an 85-year old man who had a Grade 1 NET, with a small Grade 3 focus. In our case, the NET was purely composed of a Grade 1 component. We could not refer to their procedures because the prognosis of their patient was not described. We presumed they had the same clinical outcome because histologically it was exactly the same as pancreatic origin and, to date, there is no evidence that they are clinically different. Close follow-up is essential and further research is needed to clarify the nature of NETs arising from gastric heterotopic pancreas. In practice, pathologists and endoscopists should be aware of the occurrence and association of NETs with pancreatic heterotopia in the stomach.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2008.
Informed consent was obtained from all patients included in the study.
- 11.Guillous L, Nordback P, Gerber C, Schneider RP. Ductal adenocarcinoma arising in a heterotopic pancreas situated in hiatal hernia. Arch Pathol Lab Med. 1994;118(5):568–71.Google Scholar
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