Table 5. Comparison of the nevus of Ota classification methodology.

	Three-point severity scale	Tanino's classification	PUMCH classification
Measure of classification	Extent of involvement of the face	Frequency of structure involvement	Patterns of pigmentation in the trigeminal nerve branch distributions, symmetry and complications
Number of categories	3	7	15
Rate of coverage (%)	100	64.2	91
Positives	1. Convenient and simple way to describe morphology 2. High validity and reproducibility	1. Popular system that is generally and conventionally used	1. High rate of coverage 2. Well-designed background 3. Inclusion of combined disease and symmetric features
Negatives	1. Weak pathophysiologic background 2. Doesnot account for bilaterality and combined disease 3. No consensus among dermatologists	1. Low coverage rate in real cases 2. Ambiguous demarcation between subtypes 3. A conventional but imperfect method	1. Too many categories 2. Does not account for all nevus of Ota patients