Granulomatous inflammatory reaction in human gastric adenocarcinomas: a light and electron microscopy study

Granuloma is a focal, compact collection of inflammatory cells in which mononuclear phagocytes predominate. The authors report 9 cases of papillary-tubular gastric adenocarcinomas characterized by mature granulomas associated with recent microhemorrhages. Mature granulomas were composed of foamy, CD68-positive histiocytes with occasional giant cells. Hemosiderin-containing macrophages were present in the tumor stroma, suggesting phagocytosis of erythrocytes. Under electron microscopy, mature (nonepithelioid) granulomas and clusters containing 1 macrophage and 1-3 eosinophils were found. This study provides morphological examples of skewed type II macrophage infiltration in gastric adenocarcinomas that is involved in scavenging activity, particularly erythrophagocytosis, formation of mature (nonepithelioid granulomas), and heterotypic aggregation with eosinophils.