VIPoma pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Madhu Sigdel M.B.B.S.[2]Parminder Dhingra, M.D. [3] Homa Najafi, M.D.[4]
Overview
A VIPoma is a rare tumor of the non-beta cells of the pancreas that results in the overproduction of the hormone vasoactive intestinal peptide (VIP). On microscopic histopathological analysis, findings of VIPoma are composition of uniform, small to intermediate-sized cells in clusters, nests, and trabecular growth patterns with hyperchromatic nuclei and scant cytoplasm. BKJHKJJFHKH
Pathophysiology
- VIPomas are neuroendocrine neoplasms arising from the pancreas in 90% of the cases, while the remaining 10% occur in extra pancreatic tissues like bronchus, colon, liver, and neural crest-derived tissues.[1][2][3]
- When VIPoma is found in the pancreas, 75% of the tumors occur in the tail of pancreas, while 25% occur in the pancreatic head and body.
- VIPomas originate in amine precursor uptake and decarboxylation (APUD) cells of the gastroenteropancreatic endocrine system and in adrenal or extra-adrenal neurogenic sites.
- VIPoma causes cells in the pancreas to produce high levels of a hormone called vasoactive intestinal peptide (VIP).
Pathogenesis
- Vasoactive intestinal peptide hormone has three important functions[4][5]
- Stimulates secretions from the intestine and pancreas
- Inhibits gastric acid secretion
- Increases glycogenolysis
- Causes hypercalcemia and relaxes sphincters and circular smooth muscles of gut.
- VIP hormone in CNS has effect on behavior and learning as well as secretagouge.
- It induces release of prolactin, luteinizing hormone and growth hormone from the pituitary as well as regulates the release of insulin and glucagon from the pancreas.
Molecular Mechanism of VIP harmone
- Vasoactive intestinal peptide (VIP) is a structural homologue of secretin.[6]
- VIP innervates on both VPAC1 and VPAC2.
- When VIP binds to VPAC2 receptors in intestinal cells, a G-alpha-mediated signalling cascade is triggered.
- In a number of systems, VIP binding activates adenyl cyclase activity leading to increases in cAMP and PKA.
- The PKA then activates other intracellular signaling pathways like the phosphorylation of CREB and other transcriptional factors.
- Elevated serum VIP levels leading to increased intracellular cAMP causes increased intestinal secretion of water along with Na+, K+, HCO3 -, and Cl- in the intestinal lumen, as well as bone resorption, vasodilation, and inhibition of gastric acid secretion.
Gross Pathology
On gross pathology, circumscribed, solid mass composed of white tan, irregular and firm mass within fleshy parenchyma are characteristic findings of VIPoma.[7]
Microscopic Pathology
- Histologically, a VIPoma demonstrates a composition of uniform, small to intermediate-sized cells in clusters, nests, and trabecular growth patterns with hyperchromatic nuclei and scant cytoplasm. A few nests may also exhibit psuedorosettes.[6][3]
- Immunohistochemistry of VIPoma typically demonstrates positive immunoreactivity for vasoactive intestinal peptide, cytokeratin, neuron specific enolase, chromogranin, synaptophysin, and somatostatin, with negative reactivity for S100, calcitonin, PSA, CEA, insulin, glucagon, and growth hormone.
References
- ↑ Schmoldt A, Benthe HF, Haberland G (1975). "Digitoxin metabolism by rat liver microsomes". Biochem Pharmacol. 24 (17): 1639–41. PMC 5643011. PMID http://dx.doi.org/10.1016/0002-9343(87)90425-6 Check
|pmid=value (help). - ↑ Schmoldt A, Benthe HF, Haberland G (1975). "Digitoxin metabolism by rat liver microsomes". Biochem Pharmacol. 24 (17): 1639–41. PMC 5643011. PMID https://doi.org/10.1016/j.hemonc.2014.03.002 Check
|pmid=value (help). - ↑ 3.0 3.1 Natanzi, Naveed; Amini, Mazyar; Yamini, David; Nielsen, Shawn; Ram, Ramin (2009). "Vasoactive Intestinal Peptide Tumor". Scholarly Research Exchange. 2009: 1–7. doi:10.3814/2009/938325. ISSN 1687-8299.
- ↑ Holst JJ, Fahrenkrug J, Knuhtsen S, Jensen SL, Poulsen SS, Nielsen OV (1984). "Vasoactive intestinal polypeptide (VIP) in the pig pancreas: role of VIPergic nerves in control of fluid and bicarbonate secretion". Regul Pept. 8 (3): 245–59. PMID 6379759.
- ↑ Winzell MS, Ahrén B (2007). "Role of VIP and PACAP in islet function". Peptides. 28 (9): 1805–13. doi:10.1016/j.peptides.2007.04.024. PMID 17559974.
- ↑ 6.0 6.1 Joyce, David L; Hong, Kelvin; Fishman, Elliot K; Wisell, Joshua; Pawlik, Timothy M (2008). "Multi-visceral resection of pancreatic VIPoma in a patient with sinistral portal hypertension". World Journal of Surgical Oncology. 6 (1): 80. doi:10.1186/1477-7819-6-80. ISSN 1477-7819.
- ↑ APODACA-TORREZ, Franz R.; TRIVIÑO, Marcello; LOBO, Edson José; GOLDENBERG, Alberto; TRIVIÑO, Tarcísio (2014). "Extra-pancreatic vipoma". ABCD. Arquivos Brasileiros de Cirurgia Digestiva (São Paulo). 27 (3): 222–223. doi:10.1590/S0102-67202014000300015. ISSN 0102-6720.