Grade

Histologic Features

Low

Prominent cyst formation. Many more mucous cells than squamous or intermediate (basaloid) cells. Little cytologic atypia. Variable numbers of clear cells.

Intermediate

Some cyst formation. Predominantly intermediate (basaloid) cells with some mucous and squamous cells. Occasional cytologic atypia. Variable numbers of clear cells.

High

Little or no cyst formation. Predominantly squamous cells with some intermediate (basaloid) and rare mucous cells. Substantial cytologic atypia. Variable number of clear cells. Frequent mitoses or extensive necrosis favors squamous carcinoma