Composite Carcinoma of the Stomach Associated with Sarcoid-Like Granulomas

Composite glandular/exocrine-endocrine carcinoma of the gastrointestinal tract is a special tumor type composed of common adenocarcinoma and the neuroendocrine component comprising at least one-third of the whole tumor area. These tumors are rare in the stomach and mostly published as case reports. We describe a further case of a 36-year-old man being unique in that it was associated with extensive formation of sarcoid-like granulomas. Tumor consisted of, predominantly poorly differentiated, intestinal-type adenocarcinoma and poorly differentiated neuroendocrine, small cell carcinoma. The adenocarcinomatous and neuroendocrine areas were separated, but closely juxtaposed with focal areas showing gradual transition from one to another. Perigastric lymph node metastases corresponded either to neuroendocrine or adenocarcinomatous component. On immunohistochemistry, the exocrine part was positive for cytokeratin 7, whereas superficial well-differentiated parts showed positivity with cytokeratin 20 as well. The neuroendocrine component was negative with those two types of cytokeratin. Both adenocarcinomatous and neuroendocrine tumor portions showed carcinoembryonic antigen (CEA) immunoexpression. Neuroendocrine markers (chromogranin A, synaptophysin and neuron-specific enolase) were diffusely positive in the neuroendocrine component, and found only in the scattered cells within the neoplastic glands of the adenocarcinoma. Entire gastric mucosa and all perigastric lymph nodes were extensively affected by noncaseating, sarcoidlike granulomas. The absence of any clinical manifestations combined with the negative results of chest radiograph and laboratory test for the serum angiotensin converting enzyme argued against the possibility of systemic sarcoidosis.