The diagnosis of
alopecia areata is usually based on clinical manifestations. However, there are several hair and scalp disorders that share similar clinical features with
alopecia areata, such as
tinea capitis,
trichotillomania or
traction alopecia. Trichoscopy as a fast, non-invasive and easy-to-perform technique may help to identify subtle details and establish the correct diagnosis. The aim of this review is to present the spectrum of trichoscopic findings in
alopecia areata. A systematic review of the published work was performed by searching the PubMed, Scopus and EBSCO databases, complemented by a thorough hand search of reference lists. Of 427 articles retrieved, 30 studies were eligible for quantitative analysis. The reported features of
alopecia areata were: yellow dots (6-100% patients), short vellus hairs (34-100%), black dots (0-84%), broken hairs (0-71%) and exclamation mark hairs (12-71%). Tapered hairs (5-81%) were reported in few studies, but a relatively high frequency of this finding in
alopecia areata may indicate their important role in the differential diagnosis of
hair loss. Rarely reported features, which include upright regrowing hairs (11-96%), pigtail (circle) hairs (4-61%) and Pohl-Pinkus constrictions (2-10%), may also be helpful in the diagnosis of
alopecia areata. There is no pathognomonic trichoscopic marker for
alopecia areata and the most common trichoscopic features are not the most specific. Therefore, the diagnosis should be based on the coexistence of several trichoscopic findings, not on the presence of a single feature.