1. Pleomorphic Adenoma
Benign Mixed Tumor

2. the most common salivary neoplasm
parotid tumors>minor gland tumors
Although the basic tumor pattern is highly variable,
rarely are the individual cells actually pleomorphic

3. derived from a mixture of ductal and myoepithelial elements

4. Clinical and Radiographic Features
a painless, slowly growing, firm mass
at any age but is most
slight female predilection.

5. The palate is the most common site for minor gland mixed tumors
(60% of intraoral examples) >upper lip (20%) > buccal mucosa (10%).
Palatal tumors almost always are found on the posterior lateral aspect of the palate
smooth-surfaced, dome-shaped masses
Palatal tumors
are not movable

6. Histopathologic Features

7. typically a well-circumscribed, encapsulated tumor
A well-defined tumor has a thin fibrous capsule
lack of complete encapsulation is more common for minor gland tumors

8. The tumor is composed of a mixture of ductal epithelium and myoepithelial cells within a mesenchyme-like background that is highly variable
ducts
cystic structures
islands or sheets of cells
Cords of ductal epithelium Keratinizing squamous cells
mucus-producing cells
epithelium often forms

9. Myoepithelial cells with a variable morphology
The highly characteristic "stromal" changes
angular
Spindled
plasmacytoid ( resembling plasma cells )
(more prominent in tumors arising in the minor glands)
cells are rounded and demonstrate an eccentric nucleus
and eosinophilic hyalinized cytoplasm

10. Stromal changes Myxomatous background chondroid appearance
hyalinized change
Fat or osteoid (rarely)

11. Myxomatous background
Extensive accumulation of mucoid material between the tumor cells

12. chondroid appearance or chondroid metaplasia
(Vacuolar degeneration of cells in these areas)

13. Cartilage may sometimes be present in the stroma.

14. Many of the ducts and myoepithelial cells are surrounded by a hyalinized, eosinophilic background alteration

15. A "classic" appearance with ductal elements in a myxoid stroma
The tubules is composed of two layers of cells

16. Cords of ductal epithelium in a loose myxomatous stroma.