Trichotillomania associated with the "Friar Tuck sign" and nail-biting.

Trichotillomania is a form of traction alopecia resulting from compulsive repetitive removal of one's own hair. This entity can mimic the clinical appearance of many other forms of hair loss including alopecia areata, androgenetic alopecia, and tinea capitis. It is important to differentiate trichotillomania from other forms of alopecia because its treatment is quite different. We present three cases of trichotillomania demonstrating the "tonsure pattern" or "Friar Tuck sign" and onychophagia (nail-biting), which we describe as clinical identifying features of this syndrome.