Summary
A case of gastric carcinoma mostly composed of cells with histological, immunohistochemical and ultrastructural features of Paneth cells prompted a comparative investigation of the occurrence of similar cells in gastric, colorectal and mammary carcinomas. Cells containing lysozyme were demonstrated by the immunoperoxidase-PAP technique in 34.9% of 83 gastric carcinomas. They were found in 38% of intestinal-type and in 30% of diffuse-type tumours. Paneth-type granules were demonstrated ultrastructurally in 4 of 7 carcinomas in which lysozyme had been demonstrated immunohistochemically. No lysozyme was demonstrated in a series of 30 breast carcinomas and in only 1 of 27 cases of colorectal neoplasm. The possibility of using lysozyme as a marker for some carcinomas of gastric origin is considered.