Hair casts. Review and suggestion regarding nomenclature.

There are two types of hair cast. The common type is found frequently in association with parakeratotic scalp disorders. They have features allowing specific identification. They occur in children and adults of either sex. It is suggested they be called parakeratotic hair casts, as this name reflects the cause and composition of the casts. The uncommon type has specific features that are different from the common type. They are not usually associated with diseases of the scalp and have only been reported in female subjects. It is suggested they be called peripilar keratin casts, as this is the name frequently used for them. The proposed nomenclature should avoid confusion between two distinct types of hair casts that have often inappropriately been regarded as the same disorder, and which have not been previously differentiated by specific names.