Alopecia in children: the most common causes.

The differential diagnosis of alopecia in the pediatric age group is simplified by the fact that 90% to 95% of the cases are caused by four major entities: alopecia areata, telogen effluvium, tinea capitis, and trichotillomania. Careful examination of the scalp, hair, and historical pattern of the loss will usually be rewarded by the correct diagnosis.