An immunohistochemical study of adenomatoid tumors utilizing keratin and factor VIII antibodies. Evidence for a mesothelial origin.

Fifteen adenomatoid tumors were examined immunohistochemically using antibody probes to keratin and factor VIII-related antigen. Cells lining adenoid structures labeled using keratin antibody in all 15 tumors but failed to label with factor VIII-related antigen antibodies in any case. In one case tissue was retrieved from a paraffin block and studied by immunoelectron microscopy using the two antibody probes. Immunoprecipitate was demonstrated in adenoid cells adjacent to desmosomes using keratin antibody but was absent using factor VIII-related antigen antibodies. Of the two prevailing theories of origin for adenomatoid tumors, based on ultrastructural and histochemical data to date, these results are additional evidence for a mesothelial origin and fail to support an endothelial origin.