Neuroendocrine differentiation in gastric adenocarcinomas - An immunohistochemical study

Background. The stomach contains a wide variety of neuroendocrine cells. Early studies with argyrophilic stains documented the presence of these cells in gastric adenocarcinomas. Immunohistochemical techniques for demonstrating hormones are more sensitive and specific and have been applied only sporadically to gastric adenocarcinomas. Thus, the true incidence of neuroendocrine cells in gastric adenocarcinomas is questionable. Methods. Formalin-fixed, paraffin-embedded archival tissue specimens from 48 gastric adenocarcinomas were immunostained with antibodies to chromogranin A, synaptophysin, serotonin, gastrin, and neuron-specific enolase. The percentage of cells staining positively was evaluated semiquantitatively. Results. Among 48 gastric adenocarcinomas, 36 (75%) stained positively for chromogranin A, 33 (69%) stained for synaptophysin, 29 (60%) stained for neuron-specific enolase, 17 (36%) stained for gastrin, and 15 (31%) stained for serotonin. The distribution of positivity was highest for chromogranin A (7 cases positive in 26% to 75% of cells) and lowest for serotonin (14 out of 15 cases stained in fewer than 1% of the cells present). Conclusions. Immunohistochemical evaluation of neuroendocrine markers in gastric adenocarcinomas indicates that a high percentage of tumors contain widely scattered single cells with neuroendocrine differentiation. Most often, however, such cells constitute only a small percentage of the total number of tumor cells present.