Efficacy and safety of superficial cryotherapy for alopecia areata: A retrospective, comprehensive review of 353 cases over 22 years.

Alopecia areata (AA) affects anagen hair follicles, resulting in non-scarring hair loss. Since introduced by Huang et al., superficial cryotherapy has been accepted as a considerable primary therapeutic modality for AA. The aim of this study was to objectively clarify the therapeutic efficacy and safety of superficial hypothermic cryotherapy for treatment of AA. Medical records of 353 patients from 1993 to 2014 were retrospectively analyzed. According to the response to the superficial cryotherapy, patients were categorized into four groups: "marked", "partial", "poor" and "no recovery". The marked and partial recovery groups were considered as responders. The proportions of the responders among patient subgroups which were defined by various patients, disease, and treatment factors were compared. Of the patients, 60.9% were classified as responders after 3 months of superficial hypothermic cryotherapy. The proportion of the responders were higher when the treatment interval was 2 weeks or less and in the incipient disease stage, with statistical significance. No severe side-effects other than mild pain and pruritus were reported. In conclusion, superficial cryotherapy is an effective and safe therapeutic modality for AA. Especially when the treatment interval is 2 weeks or less and in the first occurrence of the disease, the therapeutic outcome is superior.