An Ultrastructural Study on Corkscrew Hairs and Cigarette-Ash-Shaped Hairs Observed by Dermoscopy of Tinea Capitis

This study investigated the formation mechanisms of corkscrew hairs and cigarette-ash-shaped hairs in tinea capitis caused by Trichophyton violaceum using SEM and TEM. SEM revealed that corkscrew hairs had bent shafts and asymmetrically disrupted cuticle layers, while TEM showed weakened hair shafts. The corkscrew hairs were covered by scales on the scalp, suggesting their formation resulted from internal hair degradation by T. violaceum and external resistance from the scales. SEM of cigarette-ash-shaped hairs showed irregularly disrupted ends, likely representing broken corkscrew hairs post-treatment.