title: Low-grade malignant myoepithelioma arising in a pleomorphic adenoma: a rare case.
abstract: Malignant myoepithelioma is a very rare salivary gland tumor that can arise de novo or within a pre-existing pleomorphic adenoma. We report a case of malignant myoepithelioma most probably arising in a pre-existing pleomorphic adenoma of the left parotid gland. The patient was a 60-year-old man who presented with a multinodular mass lesion over left side of the face and neck. He had undergone removal of a pleomorphic adenoma of the left parotid gland twice (8 and 22 years ago). Histological examination showed locally concentrated highly invasive myoepithelial cells with bland-looking morphology and no evidence of mitosis or necrosis. Immunohistochemistry confirmed the myoepithelial differentiation (S- 100+, SMA+) and a low Ki-67 labeling index (<5%).
authors.affiliation: Department of Pathology, King Khalid University Hospital, Riyadh, Saudi Arabia. eraddaoui@yahoo.com
authors.forename: Emad
authors.initials: E
authors.lastname: Raddaoui
authors.forename: Ahmed S
authors.initials: AS
authors.lastname: Al-Hujaily
authors.forename: Saleh F
authors.initials: SF
authors.lastname: Al-Dhahri
mesh_terms: D008949:Adenoma, Pleomorphic / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009208:Myoepithelioma / Q000473:pathology*; D016609:Neoplasms, Second Primary / Q000473:pathology*; D010307:Parotid Neoplasms / Q000150:complications / Q000473:pathology*