Diagnostic Pearls

* Well circumscribed, cystic with mucin pools (low grade) or infiltrative, solid (high grade)
* Varying mixture of mucous, intermediate and epidermoid cells
* Uniform cells with intracytoplasmic mucin (low grade) or pleomorphic cells with little mucin (high grade)

ADENOID CYSTIC CARCINOMA
Cribriform pattern is common

Diagnostic Pearls

* Invasion of stroma and perineural invasion
* Basaloid cells forming cribriform structures, tubules or solid islands
* Chondromyxoid matrix is absent

WARTHIN S TUMOR
Cysts and glands with lymphoid stroma

Diagnostic Pearls

* Multiple large fluid filled cysts
* Double layered epithelial lining with columnar oncocytes and basal cells
* Heavy lymphoid stroma often with germinal centers

* Simple mucin-type carbohydrate antigens (T, Tn, and syalosyl-Tn) detected13
* Low-grade type:
o characteristic profile suggestive of striated duct differentiation:
+ CK7
+ CK14
+ mitochondrial antibodies

Staging/Grading

* Traditional two-tier system
* Three-grade scheme:
o proposed by AFIP authors17–19
o based on a points system:
+ intracystic component >20%, 2 points
+ neural invasion, 2 points
+ necrosis, 3 points
+ 4 or more mitoses per 10 HPF, 3 points
+ anaplasia, 4 points
o total score:
+ 0–4 low grade
+ 5–6 intermediate grade
+ ⩾ 7 high grade20