Table I.

Grading systems for precursor lesions of squamous epithelial malignancies

WHO Classification 2005	Squamous intraepithelial neoplasia (SIN)	Ljubljana classification; squamous intraepithelial lesions (SILs)
Squamous cell hyperplasia		Simple hyperplasia
Mild dysplasia	SIN 1	Basal/parabasal cell hyperplasia
Moderate dysplasia	SIN 2	Low grade SIL
Severe dysplasia	SIN 3	High grade SIL
Carcinoma in situ	SIN3	Carcinoma in situ

Note: The categories in the different systems are not strictly comparable as different morphological and architectural criteria are used