Pathology of the Head and Neck

Major and Minor Salivary Glands Chapter 5 139Fig. 5.7. Pleomorphic adenoma: myoepithelial cells with an epithelioidcytomorphology. These cells may also be spindle-shaped,plasmacytoid (hyaline) or have clear cytoplasm. Note also a smallduct and a focus of squamous metaplasia. Keratinising squamousmetaplasia is seen in up to a quarter of pleomorphic adenomasFig. 5.10. Pleomorphic adenoma: chondromyxoid stroma containingisolated small and small aggregates of myoepithelialcellsFig. 5.8. Pleomorphic adenoma with squamous and focal mucinousmetaplasia resembling mucoepidermoid carcinomaFig. 5.11. Collagenous spherules can be seen in some benign myoepitheliomasand myoepithelium-rich pleomorphic adenomasFig. 5.9. Pleomorphic adenoma: myoepithelial cells showing anepithelioid and plasmocytoid appearanceFig. 5.12. Vascular “invasion” is a rare finding in benign pleomorphicadenoma, due to displacement of neoplastic cells intovascular spaces. It is not indicative of malignancy