Limited efficacy of diphenylcyclopropenone in the treatment of alopecia areata: Experience from a Tertiary Healthcare Institution in Singapore.

Alopecia areata (AA) is a common cause of nonscarring hair loss. Diphenylcyclopropenone (DPCP) is a form of contact immunotherapy used in the treatment of AA. We retrospectively reviewed all patients who were diagnosed with AA over a 4-year period (1st January 2012 to 31st December 2015) and who have received DPCP. Forty patients were studied in total. The mean duration of disease prior to the study was 195 days. Patients received a mean number of 14.91 sessions (range: 1-65). The mean number of sessions required before clinical response was seen was 2.33 sessions, corresponding to 0.001% DPCP. Based on the modified Global Assessment Grading System, 33.5% (n = 11) of the patients experienced less than 25% improvement, 48.5% (n = 16) experienced 25%-74% improvement and 18.3% (n = 6) experienced more than 75% improvement. One patient had severe sensitisation reaction amounting to near erythroderma which resolved completely upon cessation of DPCP therapy. No other adverse reactions were noted in the cohort. DPCP remains a valuable tool in a dermatologist's armamentarium in treating alopecia areata as it is safe, well-tolerated, and shows limited efficacy.