Abstract
Gastroenteropancreatic neuroendocrine tumors are the most incident neuroendocrine tumors. In the new WHO classification (2010) the embryological derivation of each neoplastic entity is one of the most important parameters. Gangliocytic Paraganglioma is a tumor originating in the hindgut, a rare neoplasm, generally affecting the second portion of the duodenum, the majority of which are benign.Cases of gangliocytic paraganglioma with local metastasis or local recurrence have also been reported.We describe a GP in a 48-year-old caucasian male with an unusual site (4th portion of duodenum) and an interesting immunohistochemical and molecular pattern. In particular, we examined the expression of some neuroendocrine markers and a marker of neuronal differentiation, NeuroD1, whose expression can help to better understand the nature of this neoplasia. Virtual slides: The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/3720959161096807.