Immunohistochemical and electron microscopic study of twelve adenomatoid tumors.

Twelve adenomatoid tumors were examined immunohistochemically with antibody probes to keratin and factor VIII-related antigen (FVIII-RA). None of the tumors labeled with FVIII-RA antibodies, whereas all but one labeled for keratin. Electron microscopy was done on tissue from paraffin-embedded blocks from all but one of the adenomatoid tumors. Both the immunohistochemical and electron microscopic results favor a mesothelial origin of adenomatoid tumors.