Short anagen syndrome: A case series and algorithm for diagnosis.

Background: The short anagen syndrome (SAS) is a rare idiopathic pediatric disorder characterized by the short duration of the anagen phase. SAS mainly affects Caucasian children. Parents complain of their child's inability to grow long hair. Topical minoxidil may be an effective treatment for SAS; however, a slow spontaneous improvement is typical. Objective: Our aim was to collect data on out cases of SAS and create an algorithm to facilitate diagnosis of SAS. Methods: A retrospective review of 25 patients with SAS was performed within the Dermatology Department of the University of Bologna. We collected data regarding symptoms, pull test, hair card test, trichoscopy, trichogram, treatments, including biotin and minoxidil, and clinical outcome. Results: Characteristic findings included parental reporting that the hair had not required a haircut, hair card test showing hairs with conical-shaped tips, and hair shafts of different diameters, with more 10%-20% of hair shafts less than 60 μm thick on trichoscopy. Trichogram revealed an increased percentage of telogen hair with normal hair shafts and tapering ends. The mean anagen-to- telogen ratio was 66:34 (normal ratio 90:10). Conclusion: We developed an algorithm to facilitate the diagnosis of this rare hair disease using clinical examination and invasive and non-invasive testing to differentiate SAS from other forms of pediatric alopecia. In conclusion, the collected data of the therapy showed that biotin alone or in combination with topical minoxidil is an effective treatment for SAS.