Myoepithelial carcinoma ex pleomorphic adenoma of salivary glands: a problematic diagnosis.

We report the case of a 77-year-old woman who presented with a 6-year history of pleomorphic adenoma with multiple recurrences. Despite the clinical suspicion of a malignant process, the detection of myoepithelial carcinoma ex pleomorphic adenoma was not achieved by means of a preoperative biopsy or a frozen section removed intraoperatively, as the lesion only showed mild cytological atypia with no frank malignant features. Only a thorough evaluation of the resected tumor enabled the diagnosis of a malignancy. We discuss the difficulties that may be encountered in attempting to diagnose these rare myoepithelial lesions by means of small biopsy specimens.