Adenomatoid tumours: a mucin histochemical and immunohistochemical study.

We have examined 16 cases of adenomatoid tumour using a panel of monoclonal and polyclonal antibodies and also stained them for the presence of hyaluronidase-sensitive alcianophilic material. Fourteen cases expressed cytokeratins and a proportion of these also expressed S-100 protein, neuron-specific enolase, vimentin, and human milk fat globule protein 2. The same 14 cases also showed hyaluronidase-sensitive staining with alcian blue. No expression of factor VIII-related antigen was seen in these cases. We conclude that this provides further evidence of a mesothelial origin of these tumours. The remaining two cases did not express cytokeratins and no hyaluronidase-sensitive staining with alcian blue was seen. They did however express factor VIII-related antigen. Although they were morphologically indistinguishable from the other 14 cases, we suggest that they should be more properly regarded as angiomas.