Consideration on a case of carcinoma ex pleomorphic adenoma of the parotid gland

The authors report a case of carcinoma in an ex pleomorphic adenoma of the parotid gland that was recently referred to their attention. This form of carcinoma is not very frequent and in the literature it is reported in a percentage of cases ranging from 1.5 to 12%. The pathogenesis of this neoplasia is controversial and at the present state of the art there are authors who support the hypothesis of a malignant transformation of a previous pleomorphic adenoma, and those who sustain the onset of the tumour ex novo. At present, there is a tendency to differentiate the carcinoma ex pleomorphic adenoma from the malignant mixed tumour: the histological analysis of the former in fact shows a benign stromal component typical of pleomorphic adenoma associated with a malignant epithelial component, whereas in the malignant mixed tumour both the mesenchymal and epithelial components are malignant. The authors use this case report as a starting point to review their 20-year experience, of pleomorphic adenoma in order to evaluate the behaviour of this tumour, above all in relation to the phenomenon of recidivation and cancerization. They report recidivation in 3.5% of cases and no malignant degeneration. The surgical approach used varied depending on the site and size of the neoformation, as well as on whether the tumour was primary or recurrent.