Small cell carcinoma of the stomach: a clinicopathologic study of 17 cases.

Of 17 cases of small cell carcinoma of the stomach, three were early and 14 were advanced. Grossly, the tumors were mostly polypoid at the early stage, and as they advanced, deep ulcerations developed. Histologically, only one tumor was "oat cell type," and the other 16 were "intermediate cell type." With regard to tumor components, five were "pure" tumor, and 12 were "composite" admixing glandular and/or squamous differentiation. Argyrophil cells were seen in eight tumors. Immunohistochemically positive cells for chromogranin, neuron-specific enolase, and keratin were seen in 12, 10, and 7 tumors, respectively. Carcinoembryonic antigen was negative in the small cell component of most tumors as opposed to strong positivity in the glandular component. Electron-dense core granules were evident in seven of nine tumors examined. These findings suggest that histologic variety is quite characteristic of the small cell carcinomas of the stomach, and this type of carcinoma takes an aggressive clinical course like its counterparts in other organs.