BACKGROUNDThe nevus of Ota, is a common benign pigmentary dermatosis, mainly involve innervation area of first and second branch of trigeminal nerve. The classification of nevus of Ota was proposed by Tanino, based on 26 cases of nevus of Ota from 1937 to 1940. Studies about its classification are rarely seen in last 70 years, while it is still practical today.

METHODSBased on the clinical photographs, 1079 consecutive patients with nevus of Ota were verified and reclassified according to the innervation areas of the trigeminal nerve branches.

RESULTSIn these 1079 cases, 866 patients were in line with Tanino's classification (80.26%), and 213 patients were not (19.74%). We put forward a new clinical classification (Peking Union Medical College Hospital classification, PUMCH classification) of nevus of Ota based on the innervation area of the trigeminal nerve branches, composed of 5 types and 14 subtypes. The 5 types were as follows: Type I - pigmentation maculeses involving the innervation area of one of the three trigeminal nerve branches, of which there were 424 cases (39.3%), comprising 6 subtypes; Type II - pigmentation macules involving the innervation area of two branches of the three trigeminal nerve branches, of which there were 221 cases (20.48%), comprising 4 subtypes; Type III - pigmentation macules involving the innervation area of all three trigeminal nerve branches, of which there were 361 cases (33.45%), comprising 2 subtypes; Type IV - bilateral type, in which the pigmentation macules involves the bilateral cheek, of which there were 63 cases (5.84%), comprising 2 subtypes; and Type V - complications occurred in the patient, of which there were 10 cases (0.93%).

CONCLUSIONThe new classification of nevus of Ota is based on the innervation area of the trigeminal nerve branches, and it covers all types of Tanino's classifications; on that basis, some new types and subtypes are brought in and cover almost every clinical condition.