Topical diphenylcyclopropenone in the treatment of alopecia areata: A 10-year follow-up of 86 cases in a single center

Background: Diphenylcyclopropenone (DPCP) is a topical contact allergen used for contact immunotherapy in alopecia areata (AA). Objectives: We aimed to evaluate the treatment effectiveness and prognostic factors in Taiwanese patients with AA treated with topical DPCP. Methods: We performed a retrospective study of all consecutive patients with AA affecting more than 10% of scalp area treated with topical DPCP for more than 90 days. Results: Eighty-six patients were assessed in the study. The greatest hair regrowth percentages of 0%, 1%–25%, 26%–50%, 51%–75%, and 76%–100% were 26.7% (23/86), 7.0% (6/86), 2.3% (2/86), 10.5% (9/86), and 53.5% (46/86) of patients, respectively. 32.6% (28/86) of patients achieved near-complete remission (with or without maintenance DPCP therapy), defined as more than 90% sustainable hair regrowth. Positive prognostic factors include older age of onset, shorter duration of AA before DPCP treatment, less severity of hair loss, and no nonscalp hair loss. Multivariate logistic regression analysis showed that more than a 2-year duration of AA before DPCP treatment (P = 0.015) and more than 90% of hair loss (P = 0.032) had a poorer treatment outcome. Factors including eczematous sensitization reaction, history of atopy, adverse reactions, or concentrations of DPCP do not predict treatment effectiveness. Pigmentary change may cause cosmetic concerns in Chinese ethnicity. Conclusion: Topical DPCP is effective for AA. Various factors were associated with the clinical outcomes. Monitoring the possible adverse events is warranted.