Efficacy and safety of anthralin in combination with diphenylcyclopropenone in the treatment of alopecia areata: a retrospective case series.

Contact immunotherapy with diphenylcyclopropenone (DPCP) and anthralin is considered the treatment option for extensive alopecia areata (AA) unresponsive to DPCP immunotherapy alone. Only one study has described the efficacy of combination therapy; therefore, we investigated whether topical DPCP and anthralin can promote hair regrowth in DPCP-non responders. In this retrospective case-series we analyzed the efficacy and side effects of DPCP with anthralin in AA patients who did not respond to several months of treatment with DPCP alone. Thirty-two DPCP-nonresponsive AA patients were treated with DPCP and anthralin for the average of 8.3 ± 3.8 (3-17) months. During the treatment, 40.62% of patients (13 patients out of 32) had terminal hair regrowth. The mean of hair regrowth rate was 41%; it was mainly as partial hair regrowth (˂ 50%) and 27.27% of cases achieved > 50% terminal hair regrowth. Treatment response strongly related to the duration of combination therapy (p value ˂ 0.001), but we did not find any relation with other demographic characteristics. The first signs of response to treatment were noticed 2-12 months (5.5 ± 3.4) after initiation of combination therapy while there was a positive correlation among the duration of treatment and percentage of hair regrowth (p < 0.001). The most common complication was bullae (25%), and the least frequent side effect was generalized pruritus (3.1%). The combination therapy with DPCP and anthralin could be effective to treat DPCP non-responder AA patients. Additionally, the higher treatment response could be achieved by longer treatment duration.