Traumatic Alopecia

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Traumatic alopecia results from the forceful extraction of hair secondary to mechanical friction, pressure, or physical trauma. Types of traumatic alopecia include self-inflicted trichotillomaniatraction alopecia from tight braids, ponytails, or hair-straightening practices; prolonged pressure on the scalp of supine infants; and alopecia secondary to physical abuse. Traumatic alopecia associated with abuse can be challenging to distinguish from other forms of alopecia.

In traction alopecia, if the stimulus causing the traction is removed early, affected hair will recover. However, chronic long-term friction can cause permanent hair loss. Traction alopecia secondary to braids often results in hair loss on the scalp margin. It is more common in females and African Americans due to hair-styling practices for tight braids or the use of chemical hair straighteners.

Trichotillomania is usually diagnosed in adolescents and pre-teens. It often starts during times of psychosocial stress such as hospitalization or familial discord. It is characterized by irregular patches of alopecia without evidence of scarring. Interestingly, the backgrounds in which trichotillomania develops and child abuse occurs are similar. Factors such as violence within the family, strained parental relationships, and a stressful environment such as illness or unemployment increase the risk of both occurring in children.

Pressure-induced alopecia refers to hair loss induced by localized pressure on the scalp due to prolonged immobilization. This results in a focal area of hair loss occurring several days to weeks after the initial trigger. The alopecia may be nonscarring (if diagnosed early) or scarring (if diagnosed is delayed). Any age group may be affected, including neonates and children.

In cases of localized hair loss in children, especially if a mechanical alopecia such as trichotillomania or traction alopecia is being considered, the possibility of child abuse should also be in the differential. Alopecia from abuse is classically associated with other signs of trauma such as scalp bruising and tenderness.

Look For

Distinguishing characteristics of alopecia secondary to child abuse include signs of trauma with underlying scalp hematoma, hemorrhage, tenderness, and irregular outlines of localized hair loss. Hair breakage and subsequent regrowth is typically at a more regular length than in chronic trichotillomania. Scaling and other signs of inflammation are absent, differentiating traumatic hair loss from tinea capitis.

In trichotillomania, look for irregular patches of alopecia with twisted or broken hairs of varying lengths. Affected areas of the scalp are not completely bald. Focal perifollicular erythema, hemorrhage, and/or crusting may also be present. These patches are commonly located on the frontoparietal or frontotemporal areas of the scalp opposite the dominant hand. Diagnosis of the habit can be confirmed by observation.

In traction alopecia, hair loss is typically at the margins of the scalp and between braids. In the area of hair loss, fine vellus hairs are typically visible. The scalp appears normal without evidence of scarring.

In pressure-induced alopecia, a well-demarcated, discrete patch of hair loss is visible. The occipital region is commonly affected.

Common mimickers of traumatic alopecia and associated findings include the following:

  • In alopecia areata, there are typically smooth areas of hair loss in round, well-delineated patches. Erythema and broken hairs are absent, but “exclamation point hairs” with a thinned base are present peripherally in the patch. Alopecia may extend to involve all the hair on the body (alopecia totalis and universalis).
  • Tinea capitis typically has associated scaling and erythema. Examination of plucked hairs with potassium hydroxide (KOH) and fungal culture showing hyphae are diagnostic.
  • Seborrheic dermatitis is often associated with erythematous papules and plaques with waxy scale distributed on the scalp, face, neck, behind the ears, or in the diaper area.

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