Frequency and clinical characteristics of hydroxychloroquine-induced pigmentation in Japanese paediatric patients: a...

To investigate the frequency and characteristics of HCQ-induced pigmentation in Japanese paediatric patients. This retrospective cohort study enrolled Japanese children who received HCQ for ≥ 3 months. Data were collected from medical records, caregiver or patient questionnaires on awareness of pigmentation, and physical examination findings. The primary outcome was the frequency of HCQ-induced pigmentation. Twenty-six patients were included. Of these, 25 (96.2%) were female (median age: 15 years; first to third quartiles [Q1-Q3]: 12.0-16.8). Eleven patients had pigmentation (42.3%). Kaplan-Meier analysis demonstrated that the median time to the onset of pigmentation was 42 months (95% confidence interval: 30-not reached), and no new cases occurred after 48 months. The median observation period in the pigmentation and non-pigmentation group was 46 months (Q1-Q3: 27-51) and 24 months (Q1-Q3: 6-54), respectively. The cumulative HCQ dose per body weight was 4.0 g/kg (Q1-Q3: 2.7-5.4) in the pigmentation group and 3.0 g/kg (Q1-Q3: 0.6-5.5) in the non-pigmentation group. The Fitzpatrick skin types in the pigmentation group vs. non-pigmentation group were: type II (18.2% vs. 60%), type III (36.4% vs. 20%), type IV (36.4% vs. 20%), and type V (9.1% vs. 0%). Six of the 11 patients with pigmentation discontinued HCQ, as a result of which three experienced improvement in their pigmentation. All the improvements were noticeable within 2-6 months after discontinuing the therapy. HCQ-induced pigmentation may not be a rare adverse effect in children. Although the pigmentation may improve after discontinuing HCQ, treatment continuation or discontinuation should be carefully considered according to the activity of the underlying disease.