Alopecia and hair disorders in children

Overview & Definition

Picture an eight-year-old girl whose mother has just noticed a coin-sized, completely bald, smooth patch behind her left ear. The skin looks normal, there is no scale and no redness, and around the edge are a few short hairs that taper to a fine point. This is alopecia areata, the archetypal non-scarring alopecia of childhood, and the smooth bald patch with those tapering exclamation-mark hairs is the single most useful clue that the cause is autoimmune rather than infectious or behavioural. [1]

Now picture a different child: a ten-year-old who, six weeks after a nasty febrile illness, finds handfuls of hair on her pillow and in the shower drain. There is no bald patch, just generalised thinning all over the scalp. This is telogen effluvium, the common reactive shedding that follows a trigger by two to three months, and the diffuse pattern and the timing point straight to a disturbance of the hair cycle rather than to a discrete scalp disease. [10]

A third child, a twelve-year-old boy, has an odd, irregular area of thinned hair over the crown with hairs of all different lengths sticking up, and the scalp beneath looks entirely normal. He denies pulling at it. This is trichotillomania, a body-focused repetitive behaviour, and the varying lengths on a normal scalp are the signature. [8]

Alopecia simply means loss of hair from where it normally grows, and classifying it turns on one question: is the follicle preserved or destroyed? In the common, non-scarring disorders the follicle survives, the skin surface is normal, and regrowth is possible. In the rare, scarring (cicatricial) disorders the follicle is permanently destroyed and the skin is altered. Most paediatric hair loss is non-scarring, so the central task is to recognise the pattern of each common form, to identify the few scarring causes early before the follicle is lost, and to choose treatment by the diagnosis rather than reaching for a generic hair lotion. [12]