Hair shaft abnormalities

1) Increased fragility - monilethrix, pili torti,trichorrhexis invaginata, trichorrhexis nodosa, trichoschisis
2) Without fragility - pili annulati, uncombable hair, loose anagen hair



Pili torti - twisting of hair, flattened hair with rotation of 180 degree around long axis at irregular interval
eg. Menkes' syndrome, Bjornstard syndrome
Trichorrhexis nodosa is the fraying of hair ends so that the resemble a "broom-stick" or "paint brush".
eg. argininosuccinic aciduria

Trichoschisis or clean fracture of the hair shaft.
eg. Tay's syndrome is also known as trichothiodystrophy

Trichorrhexis invaginata or bamboo hair.
eg. Netherton's syndrome

Monilethrix means beading of hairs, it is an Autosomal Dominant condition.
Abnormality is in gene coding for human hair keratins hHb1 and hHb6.
Pili Annulati is the alternating light and dark bands secondary to air-spaces seen in normal light and has been associated with alopecia areata.