Hair Shaft Dysplasias
Hair shaft dysplasias are malformations of hair shafts. Most cases are congenital, hereditary or not; others are acquired (e.g., bubble hair). The malformations may involve a localized or generalized defect, but always follow a characteristic morphologic pattern [1,2]. The defects may be restricted to the hair or even constitute a diagnostic clue pointing to a genodermatosis (e.g., Netherton syndrome, tricho thiodystrophy). Classification of hair shaft dysplasias is difficult but for practical purposes we accept the scheme shown in Table 1.1 [2,3].