Topical Immunotherapy of Alopecia Areata: A Large Retrospective Study

Introduction: Topical immunotherapy is frequently used in the treatment of alopecia areata (AA) although few studies report long-term follow-up. Our goals were to determine the efficacy and the prognostic factors of topical immunotherapy in a large cohort of patients with AA treated in the departments of Dermatology and Venereology of Bergamo, Como and Pavia, from 1978 to January 2016. Methods: A total of 252 patients with AA were evaluated retrospectively. Results: All our patients developed an allergic reaction to a 2% solution of dinitrochlorobenzene (DNCB) or squaric acid dibutylester (SADBE) or diphenylcyclopropenone (DPCP). No patients discontinued therapy because of side effects. In total 112 patients (44.05%, p < 0.001) had a good response. Statistical analysis revealed that the main prognostic factors influencing the clinical results were the severity of hair loss at the beginning of therapy, the duration of AA, a history of atopy (particularly eczema), and the early development of sensitization to the three sensitizers. Conclusion: Topical immunotherapy in patients with AA is quite effective, mostly well tolerated, and provides prolonged therapeutic benefits.