An Unusual Case of Multiple Gastric Carcinoids Associated with Diffuse Endocrine Cell Hyperplasia and Parietal Cell Hypertrophy

We describe a case of multiple gastric carcinoid tumors in a 47-year-old Japanese man. The patient had markedly elevated serum gastrin levels (>800 pg/mL), which were suppressed by secretin-pancreozymin administration. In the partial gastrectomy specimen, a total of 19 carcinoids arose from diffuse linear and micronodular hyperplasia of the oxyntic mucosal endocrine cells. The carcinoid cells were chromogranin A-positive. Except for a very small number of serotonin-positive cells in several carcinoids, none of the 19 reacted with a battery of antibodies to other bioactive neuroendocrine substances. The most prominent findings in this case were peculiar fundic glands that were distended with a proteinaceous substance and lined with large hypertrophic parietal cells. At the ultrastructural level, these cells showed poorly developed intracytoplasmic canaliculi and vesicotubular profiles, yet their large cytoplasm had numerous mitochondria. On the basis of our histological and ultrastructural findings we suggest that an intrinsic HCl secretion abnormality of the parietal cells may be responsible for the patient's hypergastrinemia. Since there have been no reports on similar parietal cells changes, it is possible that our case may represent a pathological entity not previously described.