Pancreas - Gastrinoma (G cell tumor)

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Pancreas

Tumors

Gastrinoma (G cell tumor)

Reviewer: Deepali Jain, M.D. (see Reviewers page)
Revised: 6 December 2012, last major update August 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.

General
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● Functionally active and usually malignant endocrine tumour with clinical symptoms due to inappropriate secretion of gastrin (Zollinger Ellison syndrome; ZES); either sporadic non-familial with ZES (80% of cases) or familial with ZES in the setting of MEN1 (20%) (WHO)

Clinical features
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● Associated with hypersecretion of gastric acid and severe peptic ulceration
● 90% have ulcers; 85% in duodenum/jejunum, 15% in stomach
● 50% have diarrhea
● Tumors usually in pancreas or duodenum (eMedicine), peripancreatic soft tissue, gastric antrum (opposite of G cell distribution)
● Also ovary, mesentery, liver, intra-abdominal lymph nodes (unclear if due to ectopic pancreatic tissue or metastases)
● 50% are locally invasive or metastatic at diagnosis
● Zollinger-Ellison syndrome tumors are usually solitary, malignant, located in pancreas
● MEN 1 cases are less likely to be malignant, arise in duodenal wall, often multicentric

Diagnosis
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● Glucagon provocative test is useful (Surg Today 2012 Sep 16 [Epub ahead of print])

Primary lymph node gastrinoma:
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● Gastrin producing tumors in lymph nodes, with no GI or pancreatic primary
● Occur with MEN1 (Am J Surg Pathol 2008;32:1101)
● Occur in “gastrinoma triangle”: from cystic and common bile ducts to the second and third portion of the duodenum to neck and body of the pancreas
● Apparently due to gastric secreting neuroendocrine cells within these nodes (Arch Pathol Lab Med 2000;124:832)
● Also due to occult duodenal microgastrinomas with lymph node metastasis (Am J Surg Pathol 2008;32:1101)

Treatment
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● H2 blockers; surgical resection of tumor (if cannot resect, some advocate total gastrectomy)

Gross images
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Lymph node: largest (2.5 cm) of 5 pancreatoduodenal lymph nodes with endocrine tumor tissue (gastrin+) found in 57 year old man with ZES; no tumor found in pancreas or duodenum; patient had Billroth II gastric resection 12 years prior

Micro description
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● Non-neoplastic pancreas shows large islets and nesidioblastosis
● Malignant tumors are histologically bland
● Associated with pancreatic polypeptide cell hyperplasia (Hum Pathol 1997;28:149)

Micro images
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Malignant tumor has trabecular pattern, hyaline and fibrous tissue between epithelial cell cords

Lobular-trabecular pattern and scattered gastrin+ cells

Duodenum: tumor cells infiltrate Brunner glands and are gastrin+

Duodenum: gastrinoma in MEN1 patient arises in deep crypts of mucosa and invades submucosa deeply (immunofluorescence)

Electron microscopy description
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● Granules similar to VIP, normal gastrin producing cells: small, electron dense

Electron microscopy images
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Tumor cells contain typical vesicular G-cell granules as well as nondiagnostic dense granules

Tumor cells contain small, nondiagnostic secretory granules

End of Pancreas > Tumors > Gastrinoma (G cell tumor)

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