Loose anagen syndrome and loose anagen hair.

Loose anagen syndrome, or loose anagen hair, is a recently described condition of unknown etiology that may be under-recognized. The typical patient is a child with sparse fine hair that can easily be pulled out. The diagnosis is confirmed by microscopic examination of firmly pulled hairs, many of which are in the anagen phase but lacking an inner and outer root sheath and demonstrating a ruffled cuticle. Some presentations of alopecia areata may be confused with this condition, but the pull test analysis serves to differentiate them. A variety of theories have been postulated to explain the pathophysiology of loose anagen syndrome. In some cases, there is an autosomal dominant pattern of inheritance. In most cases, this condition spontaneously improves with age.