| Popis: |
Precise epidemiological data on pancreatic endocrine tumors (PETs) are lacking, even though increased knowledge of the clinical symptoms, pathological characteristics (in particular immunohistochemical), and improved radiological studies and laboratory tests have made detection of these tumors both easier and more frequent [1]. In general, PETs can be considered rare, with an incidence of less than 1 case per 100,000 inhabitants [1, 2], although autopsy data have suggested an incidence of up to 1.5% in the general population [3]. PETs represent about 8–10% of all pancreatic neoplasms [2, 4]. To date, there is no general agreement regarding their cytohistological origin: an early hypothesis was that they derive from islet cells, although the possibility that they arise from pluripotential (neuroendocrine) stem cells in the epithelial duct is another plausible alternative [5]. The study of transgenic mice, moreover, has demonstrated that both cells destined for endocrine differentiation and differentiated adult endocrine cells can give rise to endocrine tumors [6, 7]. In any case, PETs and the entire gastrointestinal tract express a phenotype similar to cells of the socalled diffuse endocrine system (DES) [8], a fact that has facilitated their study from pathological/histological and immunohistochemical standpoints. The World Health Organization (WHO) [9] proposed a classification system in 2000 that uses the term “endocrine,” recognizing the histogenic relationship of these neoplasms with endocrine organs and/or cells of the DES. |
