Trichoscopy: a new frontier for the diagnosis of hair diseases

Trichoscopy is hair and scalp dermoscopy using a handheld dermoscope or polarized light video microscope. This article shows the revised trichoscopic algorithm for common hair loss diseases. For the algorithm for cicatricial alopecia, loss of orifices, micropustules and/or hair tufting with six or more hairs should be carefully observed. When loss of hair orifices cannot be seen in the hair loss area, diagnosis as noncicatricial alopecia is established. Among noncicatricial alopecia, alopecia areata is most commonly encountered and should be mainly considered for differential diagnosis. Therefore, the first check point is yellow dots, black dots or broken hairs. The hallmark of androgenetic alopecia and tinea capitis is hair diameter diversity (≥20%) and comma hairs, respectively. Hair shaft abnormalities can be diagnosed from the characteristics of trichoscopy reported until now.