HAIR LOSS

27 HAIR LOSS

General Discussion

Hair loss, or alopecia, can be classified in various ways, but the most common classification distinguishes nonscarring from scarring alopecia. The hair loss of scarring alopecia is permanent while nonscarring alopecia usually is reversible. When a patient presents with hair loss, it is important to determine if he or she is experiencing hair shedding, which is significant amounts of hair coming out, or hair thinning, which is more visible scalp without noticeable amounts of hair falling out.

Every hair follicle goes through three phases: anagen (growth), catagen (transition between growth and resting), and telogen (resting). At any given time, approximately 85% of scalp follicles are in the anagen phase, and follicles remain in this phase for an average of 3 years. The catagen phase affects 2–3% of hair follicles at a time. The telogen phase occurs last, during which 10–15% of hair follicles undergo a rest period for about 3 months. At the end of telogen, the dead hair is ejected from the skin and the cycle is repeated.

Alopecia areata is patchy hair loss of autoimmune origin. It usually occurs in well-circumscribed patches, but also may involve the entire scalp (alopecia totalis) or body (alopecia universalis). The involved scalp may be normal or show subtle erythema or edema. Short hairs that taper as they approach the scalp surface, known as exclamation-mark hairs, are characteristic of alopecia areata. Alopecia areata may be associated with thyroid disease, vitiligo, or atopy.

Androgenic alopecia, the most common form of alopecia in men and women, is also known as male-pattern balding, female-pattern balding, and common balding. Most patients with androgenic alopecia complain of thinning hair rather than shedding of hair. In some women, androgenic alopecia may be a manifestation of hyperandrogenism, so the history should focus on related signs such as menstrual irregularities, infertility, hirsutism, and acne. In an otherwise healthy woman with slowly progressive androgenic alopecia and no signs or symptoms of hyperandrogenism, no laboratory testing is required. Men with androgenic alopecia do not require a laboratory evaluation.

Cicatricial alopecia results from a condition that damages the scalp and hair follicle. Examination typically reveals plaques of erythema with or without scaling. Syphilis, tuberculosis, AIDS, herpes zoster, diskoid lupus erythematosus, sarcoidosis, radiation therapy, and scalp trauma such as burns have been associated with cicatricial alopecia. If the cause of the disorder is not apparent, a punch biopsy of the scalp may be helpful in making the diagnosis.

Scarring alopecia represents a heterogeneous group of diseases manifested by erythematous papules, pustules, or scaling centered around hair follicles, resulting in eventual obliteration of follicular orifices.

Senescent (senile) alopecia is the steady decrease in the density of scalp hair which occurs in all persons as they age. Patients will note a slow, steady, diffuse pattern of thinning hair beginning about age 50 years.

Syphilitic alopecia should be considered in every patient with unexplained hair loss. Hair loss may be rapid or slow and insidious and may be patchy (moth-eaten in appearance) or diffuse. Syphilic alopecia is a noninflammatory, nonscarring alopecia without erythema, scaling, or induration. However, in symptomatic syphilic alopecia, the patchy or diffuse alopecia is associated with the papulosquamous lesions of secondary syphilis on the scalp or elsewhere.

Telogen effluvium occurs when an abnormally high percentage of normal hairs from all areas of the scalp enter telogen, the resting phase of hair growth. Many factors can precipitate telogen effluvium, especially stress. This disorder also may develop because of normal physiologic events such as the postpartum state or because of medications or endocrinopathies. Telogen effluvium usually begins 2–6 months after the causative event and lasts for several months. Hair loss is diffuse and may also affect pubic and axillary hair. Telogen effluvium is noninflammatory, and the scalp surface appears normal. The hair pull test is positive, though the telogen count usually does not exceed 50%.

Tinea capitis is a common condition caused by dermatophytes. Tinea capitis presents with one or several patches of alopecia as well as scalp inflammation. Broken-off hair shafts may create a black dot appearance on the scalp. Fungal organisms can be displayed in a KOH preparation or may be cultured after adequate scraping of hair stubs from the periphery of the lesion.

Traction alopecia is a form of traumatic alopecia associated with certain methods of hair styling including braiding, tight curlers, and ponytails. The outermost hairs are subjected to the most tension, and a zone of alopecia develops between braids and along the margin of the scalp.

Trichotillomania is a psychiatric impulse-control disorder in which the patient plucks the hairs. The pattern of hair loss often suggests the diagnosis. One or more well-circumscribed areas of hair loss may be present, often in a bizarre pattern with incomplete areas of clearing. The scalp may be normal or may show areas of erythema or pustule formation. Laboratory testing is not required, though psychiatric consultation may be considered.

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Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off

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