A histologic and immunohistochemical study was carried out in 23 unselected nonantral gastric carcinoids and their precursor lesions classified according to Solcia et al. None of the patients showed Zollinger-Ellison syndrome. Two variants of carcinoids showing distinctive pathologic and pathogenetic characteristics were identified on the basis of presence or absence of associated chronic atrophic gastritis type A (A-CAG). Chronic atrophic gastritis type A was found in 19 cases showing either single or multiple neoplasms, tumor extension limited to the mucosa or submucosa, consistent endocrine cell precursor changes in extratumoral mucosa, and consistent hypergastrinemia and/or G cell hyperplasia. Associated precursor lesions were only hyperplastic in all but two cases with single carcinoids whereas they were also dysplastic in all but one case with multiple carcinoids. The four tumors arising in nonatrophic mucosa were all single, more aggressive, and not associated with extratumoral endocrine cell proliferations or with signs of gastrin hypersecretion. Tumor cells were diffusely immunoreactive for chromogranin A and synaptophysin but usually negative for chromogranin B or HISL-19. Scattered serotonin cells were found in ten carcinoids. They were more frequent in infiltrating than in intramucosal tumors as were the less represented pancreatic polypeptide cells whereas the reverse was found for alpha-subunit-containing cells. These results are of relevance for tumor pathogenesis and may provide the rationale for a less aggressive therapeutic approach in the patients.
A case of multiple gastric carcinoids and nonantral atrophic gastritis in which the larger tumor was a composite carcinoid-adenocarcinoma is presented. The two components of the composite tumor immunohistochemically showed clear-cut diverging functional differentiations although the available evidence supported a common histogenesis from the metaplastic intestinal epithelium of the gastric mucosa. The carcinoid tissue of the composite tumor, which showed "atypical" features, also differed from the other, pure carcinoids, in which the histologic appearance was "typical." Total gastrectomy performed 1 month after the original gastric resection with antrectomy disclosed regressive changes in the endocrine cell proliferations of the gastric stump consistent with the withdrawal of a stimulating effect of the antral gastrin.Cancer 64: 1534-1539. 1989.HE SYNDROME of multiple carcinoid tumors and T chronic atrophic gastritis of the nonantral mucosa of tlie stomach is a well recognized entity.'-3 In this syndrome an interesting although not universally accepted stimulating role of the consistently occurring hypergastrinemia in the growth of the endocrine neoplasms has been ~uggested.~ In accordance with such a hypothesis is the recent observation that regression of the carcinoid tumors may be induced by antrectomy alone, a procedure which removes the source of the sustained gastrin secretion of these patients and normalizes serum gastrin This study illustrates a case of the syndrome in which the multiple carcinoids were associated with a composite carcinoid-adenocarcinoma tumor of the stomach. This is the first report of such an association although in a previous case' carcinoids and adenocarcinoma were described as concomitant but separate neoplasms. Although both components of the composite tumor of our patient likely had the same histogenetic origin, immunohistochemically they revealed clear-cut divergences in their functional differentiation.Owing to the unexpected finding of adenocarcinomatous tissue, the gastric resection originally performed in the patient was followed by total gastrectomy. This condition allowed us to document regressive cell changes consistent with the withdrawal of gastrin trophic activity in the endocrine proliferations of the remaining gastric mucosa as early as one month after antrectomy. Case ReportIn October 1987, a 53-year-old woman was admitted to the hospital (Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Castellana Grotte, Italy) for evaluation of two pol ypoid lesions located in the anterior wall of the gastric body and measuring l .5 and l cm in diameter, respectively. The smaller polyp was excised endoscopically and found to correspond to a carcinoid tumor penetrating beyond the muscularis mucosae on histologic examination. Therefore, a gastric resection was performed. Owing to the histologic diagnosis of composite carcinoidadenocarcinoma in the larger polyp (described below) the patient underwent total gastrectomy 1 month later. Intraoperative examination did not rev...
The distribution of protein 7B2, a protein with structural characteristics of GTP-binding proteins, has been studied in normal pancreatic islets and in a series of 70 pancreatic endocrine tumours with emphasis on the co-localization of 7B2 and the different pancreatic hormones. Although all cell types of normal islets were found to store 7B2, variations from intense expression to absence of reaction were seen within each cell type. In particular, B cells showed intense immunostaining for 7B2 in small compact islets and weak or no staining in larger islets with lobular arrangement. Pancreatic polypeptide (PP) cells expressed 7B2 intensely in the PP-rich area of ventral embryological origin, but were mostly non-reactive in the PP-poor area. The A cells, located along intralobular blood vessels, were more frequently immunoreactive for 7B2 than those at the periphery of the islets. Immuno-electron microscopy revealed a preferential localization of 7B2 in secretory granules of islet cells, with more intense localization in the peripheral halo of alpha granules. Benign islet cell tumours more frequently expressed 7B2 than their malignant counterparts. Although often expressed in a lower number of tumour cells than the tumour-specific hormone, 7B2 was usually co-localized with the latter. In contrast, no relationship was found with the localization of proinsulin. It is concluded that 7B2 is a non-permanent component of the cell granule compartment, probably involved in events related to exocytosis and without relationship to intracellular prohormone processing.
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