· Account for about 75% of parotid tumors
· Arise mainly from duct epithelum or myoepithelial cells
Important histological features
· Capsule never complete
· Sheets or stands of dark staining epithelial cells
· Squamous metaplasia and focci of keratin
· Fibrous and elastic tissue
· Myxoid tissue
· Cartilage,sometimes calcified,rarelytrue bone formation.
· The fibroid,myxoid,or cartilagenous,mesenchymal elements are due to the pluripotential properties of myoepithilial cells.