Adenomatoid tumors--mesotheliomas or not? A histochemical, immunohistochemical and light and electron microscopic...

A mesothelial, endothelial and epithelial differentiation of the adenomatoid tumors is discussed in the literature. Aimed at this problem the cellular nature of 12 adenomatoid tumors was investigated by means of histochemical and immunohistochemical methods at light and electron microscopic level. In all these neoplasias prekeratin was demonstrated while factor VIII-associated antigen and myoglobin were lacking within the tumor cells. The ultrastructural picture of the tumor cells was similar to that of mesothelial cells; abundant intermediate filaments of the keratin type could be decorated by means of the protein A-gold technique in them. Furthermore hyaluronidase sensitive glycosaminoglycans but no sulfated and neutral mucoproteins were found. The results suggest a mesothelial nature of the tumor cells of adenomatoid tumors.