Alopecia areata

Published on 02/04/2015 by admin

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Last modified 22/04/2025

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185 Alopecia areata

Instruction

Examine this patient’s scalp.

Salient features

History

• Young adult (75% of patients are below the age of 40 years)

• History of atopy

• Ask whether there is a family history (25% give a family history)

• Ask the patient whether there are any local symptoms and if the hair loss is cosmetically unacceptable.

Examination

• Well-defined patch of hair loss (Fig. 185.1); short, fractured, exclamation-point hairs may be seen at periphery.

• Regrowing hair in the patch appears as a fine, depigmented downy growth.

image

Fig. 185.1 Alopecia areata.

Proceed as follows:

• Look for patches of hair loss over the eyebrows and beard area

• Examine the nails for fine pitting, transverse lines, dystrophy, fragmentation (anonychorrhexis) and ridging and 20-nail dystrophy (roughened nail surface and brittle free nail edge) (Fig. 185.2)

• Tell the examiner that you would like to:

• look for atopy
• look for other autoimmune conditions including vitiligo (see below).
image

Fig. 185.2 Nail dystrophy.

Diagnosis

This patient has alopecia areata (lesion), which is suspected to be of autoimmune aetiology; it may be cosmetically unacceptable to the patient (functional status).

Advanced-level questions

What are the signs of disease activity?

At the advancing edge, broken hairs that look like exclamation marks indicate active disease. These are very short hairs, tapering and becoming depigmented as the scalp is approached. Plucking reveals such hair to be in the telogen phase.

Mention some associated disorders

• Autoimmune conditions (vitiligo, thyrotoxicosis, Addison’s disease, pernicious anaemia)

• Down syndrome

• Hypogammaglobulinaemia.

What is the difference between alopecia totalis and alopecia universalis?

Both of these conditions can occur in alopecia areata. Alopecia totalis is the loss of all scalp hair and alopecia universalis is the loss of hair from all body sites.

Is alopecia areata associated with scarring?

No.

Mention the causes of hair loss associated with scarring

Discoid lupus erythematosus, lichen planus.

What is the treatment for alopecia areata?

• Steroids (both topical and systemic) (N Engl J Med 1999;341:964)

• Psoralen plus ultraviolet A (PUVA), but alopecia often returns after discontinuation of PUVA (Lancet 1997;349:222)

• Anthralin left on the scalp for 20–60 min

• Topical minoxidil

• Topical immunotherapy: dinitrochlorobenzene, squaric acid dibutylester and diphencyprone have been used for contact sensitization

• Antibodies to tumour necrosis factor-α.

Cessation of treatment may be associated with recurrent hair loss.

Mention some causes of drug-induced alopecia

Anticoagulants, retinoids, vitamin A, antithyroid drugs, oral contraceptives, anticancer drugs (invariably reversible).

What do you understand by the term trichotillomania?

It is the self-inflicted pulling out of one’s own hair and can be differentiated from alopecia areata as the hair loss is irregular and there is always growing hair, since these cannot be pulled out till they are long enough. These patches are unilateral and are usually on the same side as the patient’s dominant hand. The patient may be unaware of this habit.

What do you know about the growth of the hair follicle?

Each follicle has cyclical growth controlled by a constitutional ‘time clock’. It has three phases of growth (anagen) with >90% of hair in this phase, a short involutional phase (catagen) and a resting (telogen) phase. The anagen phase is 3–5 years, catagen is 2–3 weeks and the telogen phase is 2–4 months. Anagen hairs are anchored deeply into the subcutaneous fat and cannot be pulled out easily. Each hair shaft may persist on the scalp for 3 to 7 years before falling out and being replaced by a new hair. Compared with anagen hair, telogen hair is located higher in the skin and can be pulled out relatively easily. Hair found on the pillow and hairbrush is telogen hair and can be recognized by the fact that the club is depigmented as well as expanded; anagen hair obtained by traction is fully melanized.

How much hair is usually lost by a normal person?

About 70–100 hairs/day. The human scalp contains about 100 000 follicles, 5–10% are in telogen at any time, i.e. 5000–10 000. As telogen lasts for about 100 days, the number of telogen hairs pushed out each day is 70–100.

What is telogen effluvium?

It is a transitory (about 2–4 months) increase in the number of hairs in the resting (telogen) phase of the hair growth cycle. There is a sudden increase in shedding of hairs, with white bulbs about 3–5 months after a period of stress. The amount of hair loss exceeds 150/day. It is associated with high fever, stress, crash dieting, malnutrition, surgery, termination of pregnancy or oral contraceptives. The prognosis is good.

What do you know about male pattern baldness?

On the scalps of men who have a predisposition for this pattern of baldness, androgens cause a switch from terminal to vellus or vellus-like follicles and a reduction in the duration of anagen. In these individuals, androgen receptors and 5α-reductase activity (converts testosterone to 5-dihydrotestosterone) are greater in frontal hair follicles than occipital follicles; higher activites of aromatase (involved in conversion of testosterone to oestrodiol) are found in occipital follicles. This is one explanation for frontal baldness in men. Finasteride, a 5α-reductase inhibitor which does not affect the androgen receptor results in some regrowth of hair in about 70% of men after 2 years of continuous use. If treatment is successful, the drug is continued indefinitely because the balding process continues when it is stopped.

What do you understand by the term trichorrhexis nodosa?

It is the fracture of the hair shaft and is common in black patients who straighten their hair. Usually the hair regrows healthily if gentle hair-care practices are adopted.

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