Aims:To assess the degree of improvement of neck hyperpigmentation in childhood acanthosis nigricans (AN) after treatment with topical 0.1% adapalene gel and the assessment of localized tissue tolerance to the gel.Subjects and Methods:A split comparison study of the hyperpigmentation on the neck was conducted in patients diagnosed with childhood AN. Patients were treated with topical 0.1% adapalene gel for a period of 4 weeks. The skin color of their neck was evaluated at baseline, 2 weeks and 4 weeks using a skin color chart. Skin color ratio (the skin on their necks compared with the skin on their backs) was calculated for all subjects. The investigator's global evaluation (IGE) scale and the parent's global evaluation (PGE) scale were used to assess the efficacy of the patients’ treatment at the end of the 4th week.Results:The mean skin color ratio of therapeutic side was significantly decreased from the baseline scores, at weeks 2 and 4, respectively (30.1%, 18.3%, and 12.9%, P < 0.001), with marked skin improvement at 60.7% ± 28.5%. The percentage of changes of skin color ratio was consistent with the efficacy evaluations as performed by the IGE and PGE scales. Treatment-related cutaneous irritation was minimal, predominantly in the first 2 weeks of treatment and was shown to be well-tolerated at week 4 following a modification of the treatment regimen.Conclusions:The study has shown the efficacy of topical 0.1% adapalene gel in the treatment of AN, specifically, in regards to the skin darkening with minimal cutaneous irritation.

Background There have been few published randomized controlled trials for the treatment of childhood acanthosis nigricans (AN) to date. Objective To assess the efficacy of topical 0.1% adapalene gel compared to 0.025% tretinoin cream in the treatment of childhood AN. Methods An 8‐week, randomized, split‐neck, comparative study between topical 0.1% adapalene gel and 0.025% tretinoin cream for the treatment of neck hyperpigmentation associated with AN was performed. M index measured by a narrowband reflectance spectrophotometer and both investigator's global evaluation (IGE) and parent's global evaluation (PGE) scales were used to evaluate efficacy. Results There was no statistically significant difference between 0.1% adapalene gel and 0.025% tretinoin cream in the treatment of AN‐associated hyperpigmentation (P = 0.56). Mean differences in M indices between week 0 and week 8 of 0.1% adapalene and 0.025% tretinoin treatment were 24.2 ± 7.9% and 23.8 ± 8.3% improvement, respectively. Regarding treatment efficacy, 90.0% and 85.0% of participants had more than 75% improvement in IGE in 0.1% adapalene and 0.025% tretinoin treatment sides, respectively. In addition, 75.0% and 65.0% of participants had more than 75.0% improvement in PGE in 0.1% adapalene and 0.025% tretinoin treatment sides, respectively. Limitations Lack of histopathological evaluations. Conclusions We found no significant difference between topical 0.1% adapalene gel and 0.025% tretinoin in the treatment of AN.