Adenoid Cystic CA : S-100

Comments:
Adenoid cystic carcinoma (ACC) is composed of two cell types – abundant basaloid cells with myoepithelial differentiation and eosinophilic epithelial cells with ductal differentiation.

The ductal epithelial cells express cytokeratin (strongly), CEA, EMA, and CD117 (c-kit). Despite overexpression of the protein product, no c-kit mutations have been found and, not surprisingly, ACC does not respond to the tyrosine kinase inhibitor Imatinib (Gleevac) which has been successfully used to treat GIST and CML.

The basaloid cells around pseudocysts show myoepithelial differentiation and express p63, S-100 protein (patchy; shown here), actin (variable), vimentin, calponin and cytokeratin. Image courtesy of: Belinda Bunn, MD, University of Pretoria, Pretoria, South Africa.