Lysozyme in neoplastic Paneth cells of a jejunal adenocarcinoma

This is the first reported case in which neoplastic cells not of granulocytic or monocytic origin have been shown to contain lysozyme. A highly differentiated metastasizing adenocarcinoma of the jejunum is presented. Areas of the tumour contained cells resembling Paneth cells, that is, they contained cytoplasmic granules with 1) stained red with Masson's trichrome and 2) were shown to contain lysozyme by an immunoperoxidase technique. No argentaffin cells could be identified within the tumour. Staining of mucosubstance revealed large intestine-type sulfated glycoproteins in the tumour tissue. The presence of lysozyme-containing neoplastic Paneth cells suggests that the tumor: 1) originated from the mucosal crypts, and 2) had a high degree of cellular differentiation.