Expression of p16Ink4a protein in pleomorphic adenoma and carcinoma ex pleomorphic adenoma proves diversity of tumour biology and predicts clinical course.

Our study confirms no p16Ink4a expression in normal tissue, but reveals differences in expression between 'fast' and 'slow' PA. We suggest that p16Ink4a overexpression is connected to PA proliferation and subsequent malignant transformation to CaexPA. Borderline p16Ink4a staining correlates with worse prognosis of CaexPA.