Malignant pancreatic gastrinoma in a maned wolf (Chrysocyon brachyurus): case report / Gastrinoma pancreático maligno em lobo-guará (Chrysocyon brachyurus): relato de caso

A captive 12-year-old female maned wolf (Chrysocyon brachyurus), previously diagnosed with visceral leishmaniasis, developed severe myiasis in the right ear, followed by prostration and death. A firm solid nodule, measuring 1 x 3cm, was grossly observed in the pancreas. Histologically, there was neoplastic proliferation in the pancreas and pancreatic lymph node. Neoplastic cells had a neuroendocrine pattern, and were positive for gastrin and pancreatic polypeptide by immunohistochemistry. The wolf had also ulcerative gastritis. To the best of our knowledge is the first reported case gastrinoma in this species.(AU)

Uma fêmea lobo-guará de cativeiro (Chrysocyon brachyurus), diagnosticada previamente com leishmaniose visceral, desenvolveu miíase grave na orelha direita, seguida por prostação e morte. Um nódulo sólido, firme e medindo 1 x 3cm, foi macroscopicamente observado no pâncreas. Histologicamente, observou-se proliferação neoplásica no pâncreas e linfonodo pancreático. As células neoplásicas tinham um padrão neuroendócrino e foram positivas para gastrina e polipeptideo pancreático por imuno-histoquímica. A loba tinha também gastrite ulcerativa. Este é o primeiro caso descrito de gastrinoma nessa espécie.(AU)

Hypermethylation of the IGF2 differentially methylated region 2 is a specific event in insulinomas leading to loss-of-imprinting and overexpression.

Prediction of the evolution of endocrine pancreatic tumors remains difficult based on histological criteria alone. We have previously demonstrated that epigenetic changes are an early event in a mouse model developing insulinomas. Particularly, overexpression of the imprinted IGF2 was caused by the hypermethylation of CpGs in the differentially methylated region 2 (DMR2). Here, we investigated whether IGF2 hypermethylation is also observed in human insulinomas and whether this alteration is common to other human endocrine tumors of the pancreas and the digestive tract. We analyzed the methylation status of 40 CpGs located in the DMR0 and DMR2 of the IGF2 as well as in the H19 DMR by pyrosequencing in a cohort of 62 patients with pancreatic or small intestine endocrine tumors. Altered methylation patterns were observed in all tumor types for the different regions of IGF2, but not for H19. However, hypermethylation of the IGF2 DMR2 was specific for insulinomas and did not occur in any of the other types of tumors which were characterized by a loss of methylation in this region. Gain of methylation in the IGF2 DMR2 in insulinomas correlated with loss-of-imprinting and promoter 4 mediated overexpression of IGF2 at the RNA and protein level. Furthermore, a decreasing degree of methylation in the different regions of IGF2 correlated well with increasing degree of malignancy according to the WHO classification of pancreatic endocrine tumors (PETs), suggesting that methylation of IGF2 might be a useful biomarker for classification and staging of PETs.

Diagnostic and prognostic implications of the World Health Organization classification of neuroendocrine tumors.

BACKGROUND: Neuroendocrine differentiation of tumors is often difficult to establish. In the same manner, the evaluation of the prognostic role of neuroendocrine differentiation may constitute a relevant clinical problem. Although different classifications are used for neuroendocrine tumors (NET) of different origin, the last World Health Organization (WHO) classification of NET, originally proposed for gastroenteropancreatic tumors, has proved to be a practical tool to allow pathologists to uniform the diagnoses and re-classify these tumors into 3 main categories. AIM: The present study was carried out in order to evaluate diagnostic and prognostic implications of NET reclassification according to the last WHO classification of NET. MATERIALS AND METHODS: Thirty-one tumors with an initial diagnosis referable to a NET achieved before 1999 were independently evaluated by 3 pathologists on the basis of the 2000 WHO classification of NET. Immunohistochemistry for panneuroendocrine markers and Ki-67 was also performed in all cases. RESULTS: Twelve, 14, and 4 tumors were respectively reclassified as well-differentiated NET, well-differentiated neuroendocrine carcinoma and poorly differentiated neuroendocrine carcinoma; 1 tumor was reclassified as mixed endocrine-exocrine tumor. Two or more neuroendocrine markers were expressed in all NET regardless of histotype, differentiation degree, and site of primary tumor. After revision, 10 of the 31 tumors under study (32%) changed histo-prognostic category when compared to the initial diagnosis. Ki-67 score was the best predictor of survival at the multivariate analysis. CONCLUSION: The WHO classification is suitable to accurately reclassify tumors with an initial diagnosis referable to a NET and to separate these tumors in 3 well-distinct histo-prognostic categories with relevant clinical implications. Ki-67 score seems to be a better predictor of survival than the degree of differentiation.

Endocrine precursor lesions and microadenomas of the duodenum and pancreas with and without MEN1: criteria, molecular concepts and clinical significance.

Proliferative changes in the neuroendocrine cells that precede neoplasia are of interest for the understanding of tumorigenesis and the early recognition of neuroendocrine tumors. This review focuses on precursor lesions of duodenal and pancreatic neuroendocrine tumors in multiple endocrine neoplasia type 1 (MEN1) and also discusses 2 new disease entities of pancreatic microadenomatosis. The gastrinomas observed in MEN1 are almost exclusively localized in the duodenum and are multicentric. It has been shown that, in contrast to sporadic duodenal gastrinomas, they are associated with hyperplastic gastrin cell lesions and tiny gastrin-producing microtumors less than 500 microm in diameter. In the pancreas, microadenomatosis (multiple tumors up to 5 mm in diameter) is a feature of MEN1. These microadenomas predominantly express glucagon and pancreatic polypeptide, but do not cause a hormonal syndrome. Approximately 50% of MEN1 minigastrinomas in the duodenum and almost all microadenomas in the pancreas show allelic deletion of the MEN1 gene and therefore may represent 'initial' neoplasms. In contrast, endocrine cell precursor lesions retain heterozygosity. Pancreatic microadenomatosis was also found unassociated with hereditary syndromes and 2 monohormonal types were identified: (1) glucagon-producing microadenomatosis and (2) insulin-producing microadenomatosis, both associated with macrotumors. Whether these types of microadenomatosis represent novel disease entities and how to diagnose and treat these patients remains to be clarified by further studies.