Analysis of trichoscopic signs observed in 24 patients presenting tinea capitis: Hypotheses based on physiopathology and proposed new classification

Abstract

Trichoscopy (hair dermoscopy) is a non-invasive and very useful technique for the diagnosis and follow-up of hair and scalp disorders. In tinea capitis, specific aspects of the hair shaft have been described, with the main ones being: comma hair, corkscrew hair, bar code-like hair (BCH) and zigzag hair (ZZH). Herein we report on a retrospective study of 24 patients with tinea capitis (TC). All patients underwent trichoscopic examination and mycological culture. Trichoscopy was abnormal in all 24 patients showing hair-shaft abnormalities. We observed three types of images depending on the nature and the mechanism of infection and discuss the different trichoscopic aspects of the hair shaft (comma hair, corkscrew hair, bar code-like hair, zigzag hair, broken hair and black dots) resulting from 3 mechanisms of penetration of the fungus in the hair shaft (endothrix, ectothrix and ectothrix-endothrix). All patients had positive mycological cultures: 15 with trichophytic TC (8 with Trichophytontonsurans, 5 with T.soudanense and 2 with T.verrucosum) and 9 microsporic TC (7 with Microsporumaudouini, and 2 with M.canis). We propose for the first time, to our knowledge, a classification of trichoscopic signs of TC. This classification will enable rapid diagnosis and prediction of the nature of the fungus before mycological culture. Our study shows the importance of trichoscopy in the diagnosis and monitoring of TC as well as its very good correlation with mycological culture. We propose a new classification of trichoscopic signs dependent on the nature of the mycological agent and the mechanism of infection. Further prospective studies with more patients are needed to confirm this classification.