Carcinoma in pleomorphic adenoma

Carcinoma in pleomorphic adenoma (Ca in PA) is a rare lesion which is composed of a malignant tumor or is transformed from a benign pleomorphic adenoma. We describe immunohistochemical investigations of tumor markers in 5 cases of carcinoma in pleomorphic adenoma; keratin (polyclonal; TK: 41-65 kDa, monoclonal: KL1: 55-57 kDa; PKK1: 40, 45 and 52.5 kDa), vimentin, desmin, involucrin (Inv), S-100 protein, lysozyme (LZ), lactoferrin (LF), α1-antitrypsin (α1-At), α1-antichymotrysin (α1-Ach), carcinoembryonic antigen (polyclonal; CEA (P), NCA-absorbed polyclonal; CEA (N), monoclonal; CEA (M)), and epithelial membrane antigen (EMA).1) Keratin which is an intermediate sized filament protein and an epithelial marker, is not a specific marker for this tumor. It showed both malignant and benign tumor cells, and did not discriminate the two lesions. Inv is lackeing in the tumor, but is detected in squamous metaplasia or keratinizing of the changed area.2) S-100 proteins showed great variations for staining in tumor cells. Normal myoepithelial cells do not always show positive reactions.3) LZ, LF, α1-At, and α1-Ach showed mostly negative in the cells of Ca in PA. They were associated with bacteriostatic mechanisms as a focal defence mechanism.4) Polyclonal CEA reaction is not specific, and the reaction product appeared in both carcinoma and pleomorphic adenoma. True CEA reaction between cancer and pleomorhic adenoma tissues was unexpected.5) EMA is a more useful and suspected tumor markers in correlation with histologic malignancy, grading and/or possibility.