Structural Abnormalities of the Hair
Pili annulati is a disorder that produces a spangled appearance to the hair, caused by alternating light and dark banding of hair shafts. This phenomenon is created by abnormal cavities in the cortex of the hair shaft, which produces lighter bands seen on clinical examination.
Treatment in pili annulati is often not required as it is a benign condition in which patients rarely seek medical attention. The shiny appearance of the hair is infrequently bothersome, and some patients even consider it attractive
Trichoschisis is very similar to trichoclasis. It is a sudden hair shaft break across the diameter of the fiber. The difference is that in Trichoschisis there is a localized absence of the cuticle at the site of the fracture. This form of clean break in hair fiber is usually seen in people who have congenitally abnormal hair growth, as in trichothiodystrophy, or sometimes those who excessively manipulate their hair and strip away the cuticle. Absence of cuticle in focal areas along a hair shaft creates weak spots. Any tension created in the hair through styling, brushing or combing may cause the fibers to snap at these weak points.
Treatment involves improving metabolism of sulfur or if it is an acquired condition, reduction in hair manipulation.
Monilethrixis a condition that affects hair growth. Its most characteristic feature is that individual strands of hair have a beaded appearance like the beads of a necklace. The name monilethrix comes from the Latin word for necklace (monile) and the Greek word for hair (thrix).
No definitive treatment is recognized, but topical minoxidil 2% may lead to an increase of normal hair shaft without any adverse effects in one report.
Trichorrhexis nodosa is a defect in the hair shaft characterized by thickening or weak points (nodes) that cause the hair to break off easily. This group of conditions contributes to the appearance of hair loss, lack of growth, and damaged-looking hair.
Excessive brushing, hot combing, permanent waving, and other harsh hair treatments should be avoided.
Trichorrhexis invaginata is a distinctive hair shaft abnormality that may occur sporadically, either in normal hair or with other hair shaft abnormalities, or regularly as a marker for Netherton's syndrome.
Pili torti is a rare hair condition characterized by fragile hair. Acquired cases of pili torti may be associated with anorexia nervosa, malnutrition, oral retinoid treatment, or inflammatory scalp conditions (e.g., cutaneous lupus erythematousus).
In acquired pili torti treatment involves stopping the exposure to the casative agent (e.g., to oral retinoids) or condition (e.g., improving diet). There is no specific treatment for the inherited form of pili torti. It may improve spontaneously after puberty.
Trichonodosis is characterized by knotted hair on the distal portion of the hair shaft. This may be spontaneous or secondary to mechanical factors like vigorous scratching or combing the hair. Trichonodosis may be associated with abnormal scalp and body hair growth