Trichorrhexis Nodosa (TN) is an uncommon hair disorder than result in thinning of the hair.
Features:
(1) nodules along the hair shaft
(2) associated with easy hair breakage
Trichoscopy is useful for diagnosis.
The sites of the nodules may be proximal, distal or localized.
It may be hereditary or acquired.
Hereditary causes include:
(1) ectodermal dysplasia
(2) inherited metabolic disorders involving amino acids
Acquired causes:
(1) hypothyroidism
(2) iron deficiency
(3) repetitive hair trauma (mask wearing, twirling, bleaching, cosmetic hair care products)
(4) hypovitaminosis A
(5) chemical exposures
(6) malnutrition
The acquired forms respond to correction of the underlying cause.
Differential diagnosis:
(1) trichorrhexis invaginata
