Islet cell tumor

Uses Pancreatic islet cell tumors carcinoid tumors Action DNA-DNA (int -strand) cross-linking DNA, RNA, protein synth inhibitor Dose Per protocol -1- in renal failure Caution w/ renal failure [D, /-] Contra w/ rotavirus vaccine, PRG Disp Inj SE N/V/D, duodenal ulcers, depression, X BM rare nephrotox (proteinuria azotemia dose related), hypophosphatemia dose limiting hypo-/hypCTglycemia inj site Rxns Interactions t Risk of nephrotox W/... 

GLP-1 increases beta-cell mass in animals. Thus, exenatide has the potential to cause increased beta-cell mass through augmented differentiation of precursor cells and inhibition of apoptosis (9). No malignant islet cell tumors were found in 130 mice and rats who received the... 

DR has been shown to delay onset of a number of other spontaneous tumors in rodents. This includes hepatoms, breast tumors, pancreatic islet cell tumors, renal tumors, mammary gland cancers, pituitary tumors, and pheochromocytomas. Decrease in spontaneous appearance of preneoplastic foci in the liver was observed in the SPF Wistar rats. Similarly, marked reduction in spontaneous hepatoma was observed in B6C3F1 mice diet restricted for 12 months. In rodents, DR has been shown to decrease colon cancer incidence. Recently it has been shown that DR prevents spontaneous sarcomas and lymphomas in p53 mice, which are genetically susceptible to a number of neoplasms. The decrease in tumor incidence is linked to the increase in life expectancy of DR animals, especially rodents, where the incidence of spontaneous tumors is the leading cause of death in rodents. 

The nitrosoureas include streptozotocin, an agent useful in treating pancreatic (islet cell) tumors, and the carmustine, lomustine and semustine group, useful in treating brain and gastrointestinal tumors. Streptozotocin induces a reversible, mild nephropathy characterized by proteinuria in 50-70% of patients... 

Fajans SS> Vinik AL Insulin-producing islet cell tumors. Endocrinol Metab Clin North Am 1989 18 45-74. 

FIGURE 4.5 Representative spectrum examples of SELDI analysis of pancreatic juice samples bound to IMAC-3 cupper ProteinChip array. A peak of 16,570 Da (arrow) was present in the four pancreatic juice samples from patients with pancreatic adenocarcinoma (PC4, PCS, PC 18, PC24) but absent in the four patients with other pancreatic diseases (IPMN islet cell tumor (ICT) serous cystadenoma (SC)). (Reprinted from Rosty et al. [26], used with permission from the American Association of Cancer Research.)... 

Ulcerogenic and diarrheogenic islet cell tumors of the pancreas may be associated with metastases and/or hyperparathyroidism (G24). Both may lead to hyperphosphatasemia,... 

Lightman and Bloom (L15) reported a patient with a glucagon-secreting tumor situated outside the pancreas but with the histology of a malignant islet cell tumor. Serum alkaline phosphatase was normal,... 

Zl. Zollinger, R. M., and Ellison, E., Primary peptic ulcerations of the jejunum associated with islet cell tumors of the pancreas. Ann. Surg. 142, 709-728 (1955). 

Poorly differentiated endocrine neoplasms, depending on the site of origin, may produce characteristic peptide hormones. The group of poorly differentiated neuroendocrine tumors and their hormone production include islet cell tumors (insulin, glucagon, somatostatin, gastrin), pulmonary small cell carcinoma (bombesin in 45% of cases), and medullary thyroid carcinoma (calcitonin). 

Glark ES, Garney JA. Pancreatic islet cell tumor associated with Gushing s syndrome. Am Surg Pathol. 1984 8 917-924. 

Arihiro K, Inai K. Malignant islet cell tumor of the pancreas with multiple hormone production and expression of CEA and CA19-9. Report of an autopsy case. Acta Pathol Jpn. 1991 41 150-157. 

Synaptophysin Neuroendocrine tumors pituitary adenomas, medullary thyroid carcinoma, pheochromocytoma, islet cell tumors, small cell carcinoma, carcinoid and neuroendocrine Medulloblastoma, retinoblastoma, neurocytoma, ependymoma, neuroblastoma, adrenocortical tumors. Merkel cell tumors Neuronal and neuroendocrine cells, carotid body cells, adrenal cortex and medulla... 

Von Hippel-Lindau disease (VHL) is an autosomal dominant condition secondary to an alteration in a tumor suppressor gene on chromosome 3. It has incomplete penetrance and is characterized by hemangioblastomas in the retina, CNS, renal cell carcinoma, endolymphatic sac tumors, pheochro-mocytomas, papillary cystadenoma of the epididymis, angiomas of the liver and kidney, cysts of the liver, kidney and epididymis, and pulmonary arteriovenous shunts (Fig. 4.18a-c). In the pancreas, VHL may have multiple presentations, the most common being the presence of multiple small pancreatic cysts with calcifications in 40% of cases. Serous cystad-enomas, solid nonfunctional islet cell tumors, and adenocarcinoma are less common (Richard et al. 2004). 

In the pediatric population, pancreatic tumors are very unusual entities. They account for less than 5% of all malignancies in children. These tumors may arise from the exocrine or endocrine pancreas. Exocrine neoplasias include ductal adenocarcinoma, acinar adenocarcinoma, pancreaticoblastoma, or infantile adenocarcinoma. Endocrine tumors or islet cell tumors are named after the hormone produced, with insulinoma being the most common in children (Walker 1996). 

Islet cell tumors are very difficult to visualize on US however, sometimes small and well-defined hypoechoic round lesions with a hyperechoic capsule maybe found. 

Acid denaturation Gastrin-secreting islet cell tumor causing... 

The disorders associated with abnormal gastric secretion rates and the frequency with which the abnormality occurs are listed in Table 4. In the Zollinger-Ellison syndrome (ZES), basal acid secretion rates are 60% of maximal or greater (BAO/PAO O.6). In addition, decreased gastric acid secretion is rarely seen in patients with the som-atostatinoma syndrome, a condition associated with an islet cell tumor that secretes excessive amounts of somatostatin, a hormone that inhibits acid secretion. There are recent reports of decreased gastric acid, pepsin and intrinsic factor outputs as part of a gastric... 

Kazumi T, Yoshino G, Baba S (1980) Pancreatic islet cell tumors found in rats given alloxan and nicotinamide. Endocrinol Jpn 27 387-393... 

Drug tolerance Tolerance is rare in acromegaly, but in other pituitary hypersecretory tumors tolerance occurs in 10-20% of initial responders. Of carcinoid or islet cell tumors that respond to somatostatin analogues more than 50% develop tolerance within 1 year. The mechanisms of tolerance and variability in the duration of the response are not known. In some patients tolerance may be overcome by increasing the dose. 

Hyper-vascular tumors such as islet cell tumors and certain hyper-vascular (renal cell carcinoma) metastases will often appear hyper-attenuating on the pancreatic phase which allows for better characterization of these tumors (Fig. 3.11). 

Horton KM, Hruban RH, Yeo C et al (2006) Multi-detector row CT of pancreatic islet cell tumors. RadioGraphics 26 453-464... 

Fig. 8-33. Low-power microscopic view of an islet cell tumor. The tumor is separated from the normal pancreas by a thin capsule...

Neuroendocrine tumors (NET) of the pancreas are quite rare, accounting for not more than 1-5% of all pancreatic tumors (Noone et al. 2005). They arise Ifom the endocrine pancreas. Frequently they have been referred to as "islet cell tumors, although this is a misnomer. Recently they were classified according the WHO proposal, which includes histopathologic and functional parameters (Rha et al. 2007). This new classification comprises a spectrum of weU-differentiated endocrine tumors (with benign or uncertain biological behavior). 

Progress in the Insulin field has been rapid in these two years, particularly in the axea, of the blos thesis of the hormone. It is now well established that Insulin, which has two peptide chains (A, 21 amino acids and B, 30 amino acids) cross-linked by two disulfide bridges, is synthesized as a single peptide chain, prolnsulin. in which the A and B chains of inmUn are connected by a "connecting peptide" (C-peptide) chain of 33 (porcine) or 30 (bovine) amino acids. Work on prolnsulin has be reviewed, 1, 10 and the amino acid sequences of bovine and porcine proinsulins have been published. Hie amino acid composition of cod proinsulin has a o appeared Two different proinsulins have been demonstrated in the rat, 8 aod proinsulin has been Isolated from human islet cell tumor tissue cultures. The structures of porcine and bovine prolnsulins are as follows ... 

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