A case of squamous cell carcinoma ex pleomorphic adenoma in the palate: Immunohistochemical analysis and chromosomal alteration by comparative genomic hybridization

Carcinoma ex pleomorphic adenoma (CXPA) is an uncommon tumor of salivary gland; moreover, histologically, squamous cell carcinoma (SCC) is exceedingly rare. This report documents a case of CXPA arising in the hard palate, which showed transformation from pleomorphic adenoma (PA) to SCC reacted to Ki-67 immunostaining. Other immunohistochemical stains also demonstrated different immunoreactivities between PA cells and SCC cells. Comparative genomic hybridization identified a chromosomal imbalance. Gain regions of the PA were 8q11-22 and 8q24 and the loss region was 13q32-34 in PA; additionally, in SCC, regions characterized by increased DNA copy number were 8p, 8q and 12q12-15.