Vesicular monoamine transporter 2 as a marker of gastric enterochromaffin-like cell tumors

The vesicular monoamine transporter 2 (VMAT2) facilitates the ATP-dependent accumulation of biogenic amine inside the secretory granules of endocrine cells and neurons and was demonstrated in the histamine-producing enterochr omaffin-like (ECL) cells of the stomach. In the present investigation, VMAT 2 immunohistochemistry was tested in 85 endocrine tumors, of which 60 were well differentiated gastrointestinal and pancreatic growths, 5 poorly diffe rentiated (neuro)endocrine carcinomas (PDEC) and 1 mixed PDEC/ECL cell carc inoma of the stomach, 12 pheochromocytomas/paragangliomas, 3 adrenocortical lesions, 2 parathyroid and 2 lung neuroendocrine tumors. Extensive and int ense VMAT2 immunoreactivity was observed in 16 of 16 gastric ECL cell tumor s, 6 of 6 adrenal pheochromocytomas, 2 of 2 chromaffin paragangliomas and i n 3 of the 4 carotid body paragangliomas investigated. Rare VMAT2-positive cells were observed in 12 of 21 intestinal enterochromaffin (EC) cell tumor s, in 9 of 11 pancreatic neuroendocrine tumors, and in the mixed PDEC/ ECL cell carcinoma of the stomach (differentiated cells only). No VMAT2 immunor eactivity was observed in five gastrin, four somatostatin and three enterog lucagon/peptideYY tumors of the gastrointestinal tract, in six gastric PDEC s, in three adrenocortical growths, and two parathyroid and two lung neuroe ndocrine tumors. These data support VMAT2 immunohistochemistry as being a u seful tool for the diagnosis of gastric ECL cell tumors, separating them fr om all other endocrine tumors arising in the gastroduodenal area i.e., gast rin, somatostatin, EC cell and PDEC tumors, all of which proved essentially negative.