Grading systems in head and neck dysplasia: their prognostic value, weaknesses and utility

Head & Neck Oncology

Table 1 Classification systems that categorize intraepithelial head and neck lesions.[3, 11]

2005 WHO Classification	Squamous Intraepithelial Neoplasia (SIN)	Ljubljana Classification Squamous Intraepithelial Lesions (SIL)
squamous cell hyperplasia		squamous cell (simple) hyperplasia
mild dysplasia	SIN 1	basal/parabasal cell hyperplasia*
moderate dysplasia	SIN 2	atypical hyperplasia**
severe dysplasia	SIN 3***	atypical hyperplasia**
carcinoma in-situ	SIN 3***	carcinoma in-situ

* basal/parabasal cell hyperplasia may histologically resemble mild dyplasia, but the former is conceptually benign lesion and the latter the lower grade of precursor lesions.
** 'risky epithelium'. The analogy to moderate and severe dysplasia is approximate.
*** the advocates of SIN combine severe dysplasia and carcinoma in-situ.