Your patient complains about hair loss. Contribution of a skin biopsy in noncicatricial alopecias

Abstract The diagnosis of most alopecia problems is based on the clinical history and a well conducted clinical examination. The additional contributions of dermoscopy, trichoscopy and trichogram are helpful. However, a scalp biopsy is occasionally necessary to establish the correct diagnosis. The main noncicatricial alopecias are represented by androgenetic alopecia, alopecia areata, trichotillomania, traction and pressure alopecia, temporal triangular alopecia, ageing alopecia, loose anagen syndrome, telogen effluvium and anagen effluvium.