Combined adenocarcinoma and carcinoid tumor in atrophic gastritis.

The development of adenocarcinoma or carcinoid tumors in atrophic gastritis is widely documented. We report the simultaneous occurrence of gastric adenocarcinoma and carcinoid (composite tumor) in atrophic gastritis, a finding reported only twice before in the literature. This 52-yr-old man with rectal bleeding, epigastric pain, and iron deficiency anemia was noted to have multiple polypoid masses on upper endoscopy. Biopsy revealed features of both adenocarcinoma and carcinoid tumor in a background of atrophic gastritis, leading to a total gastrectomy, lymph node dissection, and liver biopsy. The gastrectomy specimen was characterized by a 6 cm pedunculated polyp and multiple sessile nodular masses between 0.4 and 2.5 cm in the background of a granular mucosa. On microscopic examination, the large polypoid mass corresponded to a well-differentiated adenocarcinoma, intestinal type, infiltrating the wall. The smaller nodules were composed of carcinoid tumors, restricted to the mucosa, or infiltrating the gastric wall. Carcinoid tumor was also seen in the large polypoid mass closely intermingled with adenocarcinoma. The carcinoid tumor metastasized to the liver. Lymph nodes showed both adenocarcinoma and carcinoid tumor. The gastric mucosa was characterized by atrophic gastritis with intestinal metaplasia, neuroendocrine hyperplasia, and microcarcinoids. The adenocarcinoma stained strongly for CK7, CK 20, MIB-1, and focally for chromogranin and synaptophysin. The carcinoid tumor was negative for CK7, CK 20 and MIB-1, and was positive for chromogranin and synaptophysin. Overexpression of p53 was noted only in the adenocarcinoma. Electron microscopy revealed neurosecretory granules in the carcinoid characteristic of a neuroendocrine tumor. Composite tumor can occur in the setting of atrophic gastritis. The findings in this patient reinforce the concept that the epithelial and neuroendocrine cells of the gastrointestinal tract both result from multidirectional differentiation of a primitive cell.