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• Commonest cause of hair loss.
• An autoimmune disease.
• Hairless, smooth areas are most often on the scalp. At the margin short remnants of broken hairs are visible (‘exclamation marks’).
• All of the scalp (alopecia totalis) or the whole body (alopecia universalis) may be involved.
• Hair typically regrows after 6–12mths, but may be recurrent.
• The larger the area of hair loss, the poorer the prognosis.
May be unintentional (e.g. chronic hair twisting due to ponytail or rubbing of occiput in babies) or intentional (trichotillomania) due to hair pulling, twisting, or cutting as part of habit or s to anxiety, chronic social depri-vation, or psychological disorder. Characteristically, there is an irregular margin, as well as bizarre patterns without complete hair loss, and broken hairs of different length. Hair re-grows once behaviour is modified.
Tinea capitus, ringworm.
Scarring alopecia Commonest cause is aplasia cutis. Circumscribed areas of the skin are absent, usually on scalp, which presents at birth with raw, red ulcer that heals with scarring and later absent hair growth. There is a significant incidence of other abnormalities (e.g. trisomies). Irreversible absent local-ized hair growth will also follow other causes of trauma (e.g. burns, skin disease, trauma).
A rare autosomal recessive condition. Hair is present in the newborn pe-riod, but total hair loss occurs over the next few months and does not regrow. May be associated with other anomalies.
Hair loss can be s to hypothyroidism, diabetes mellitus, severe systemic disease, iron or zinc deficiency, chemotherapy.
• History: include general health, recent illnesses, drug history, family history of alopecia, age of onset.
• Examination: pattern of hair loss; scalp and general examination.
• Investigations: hair M,C&S; Wood’s light (tinea capitus); scalp biopsy.
• Treat any underlying condition.
• Wigs may be helpful.
Topical steroids may be helpful for alopecia areata.
Defined as hair growth in areas not normally hairy in either sex.
• Certain rare syndromes (e.g. Cornelia De Lange syndrome, mucopolysaccharidosis).
• Drugs (e.g. diazoxide, ciclosporin, minoxidil).
• Anorexia nervosa.
• Persistence of foetal lanugo hair at birth.
Localized hypertrichosis may be associated with pigmented naevi, spina bifida occulta, inflammatory skin diseases, or topical steroids.
If required remove or treat underlying cause if possible; hair removal using depilatory creams or waxing.
Male pattern of hair growth in females.
·Androgen excess (adrenal hypoplasia or tumour, Cushing’s disease, polycystic ovary syndrome).
• Turner’s syndrome.
• Drugs (e.g. anticonvulsants, progesterones, anabolic steroids).
If there is any suggestion that not racial or familial (e.g. virilization evident).
• Plasma free testosterone.
• Plasma 17-OH progesterone.
• Serum cortisol.
• Urine steroid profile.
• Skull X-ray to detect possible pituitary tumour.
Treat any underlying disease; reassure if racial or familial; hair removal using depilatory creams or waxing.
All diseases are rare and include:
• Menkes kinky hair disease: wiry wool hair;
• Monilethrix: a rare autosomal dominant condition that causes brittle hair that fails to grow and breaks at 1–2cm;
• Pili torti: hair repeatedly twists over 180*, leading to brittle hair that ‘flickers’ under direct light;
Woolly hair syndrome: wiry woolly Afro-Caribbean-like hair in Caucasians.
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