Approach to the Problem
Hair loss, or alopecia, may be congenital, hereditary, or acquired. The distribution of hair loss may be described as localized, as in alopecia areata, or more diffuse, as in telogen effluvium. Though hair loss often occurs in isolation, it may be a sign of systemic illness. Hair growth cycle disruption in the anagen (active), catagen (regressive), or telogen (resting) phases may cause hair loss. Also, any damage to the follicle or shaft may result in hair loss, as in trichotillomania. Some causes of hair loss, such as tinea capitis, may lead to scalp scarring and permanent hair loss if left untreated, which can be psychologically damaging to the parents and the child.
Key Points in the History
• Tinea capitis is the primary cause of alopecia in African American children.
• Home remedies for a child’s scaling scalp, such as hair grease and oils, may mask the underlying scale of tinea capitis.
• Recent illness may cause the hair to enter the resting (telogen) phase and manifest as diffuse hair loss (telogen effluvium).
• Traction alopecia, from tight braiding, is a common cause of hair loss.
• Cutis aplasia and sebaceous nevus of Jadassohn may present at birth as well-circumscribed areas of the scalp devoid of hair.
• Hair loss in younger teens necessitates a search for autoimmune disorders, such as thyroid disorders or psychiatric problems.
• There may be a family history of hair loss or autoimmune disease, such as in systemic lupus erythematosus (SLE).
• Children with systemic symptoms, diffuse rash, and nail or teeth abnormalities may have hair loss as a manifestation of a more widespread disease, such as in acrodermatitis enteropathica.
Key Points in the Physical Examination
• A prepubescent child with a scaly scalp should warrant a scalp culture to check for tinea capitis.
• The breakage of hair shafts close to the scalp in tinea capitis causes the “black dot” sign.
• Kerions and pustules, host inflammatory responses to fungal infections, usually do not represent bacterial superinfection.
• Trichophyton species, accounting for more than 90% of tinea capitis in North America, do not fluoresce under a Wood lamp.
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