Alopecia Areata

Alopecia areata, also known as spot baldness, is a medical condition where hair is lost from some or all areas of the body. This condition often presents as a few bald spots on the scalp, each about the size of a coin. It is considered an autoimmune disorder, where the body's immune system attacks its own hair follicles, leading to hair loss.

While psychological stress and illness can be contributing factors, in most cases, there is no clear trigger. Individuals affected by alopecia areata are generally otherwise healthy. In severe cases, all hair on the scalp (alopecia totalis) or all body hair (alopecia universalis) may be lost.

Alopecia areata seen on the back of the scalp

Signs and Symptoms

The initial symptom of alopecia areata is typically small, round, or oval bald patches on the scalp or beard, though it can occur on any hair-bearing area of the body. The underlying skin appears unscarred and normal. Hair loss can occur over a short period, often more on one side of the scalp than the other. Some individuals experience tingling or mild pain in the affected areas.

Exclamation point hairs, characterised by being narrower along the length of the strand closer to the base, may be present around the bald patches. These hairs are very short (3–4 mm). Additionally, nails may exhibit pitting or trachyonychia.

Alopecia areata

Causes

Alopecia areata is thought to be a systemic autoimmune disorder where T cell lymphocytes attack hair follicles, causing inflammation and hair loss. Normally, hair follicles are protected from the immune system by immune privilege, and a breach in this state is considered a cause of the condition. Genetic factors play a very important role; individuals with a family history of alopecia areata are at higher risk.

The condition shares genetic risk factors with other autoimmune diseases like rheumatoid arthritis, type 1 diabetes, and celiac disease.

In alopecia areata, a hair follicle is attacked by the immune system. T-cells swarm the roots, killing the follicle, causing hair loss.

Diagnosis

Alopecia areata is usually diagnosed based on its clinical features. Trichoscopy can aid in diagnosis by showing "yellow dots," exclamation mark hairs, and "black dots." Sometimes, a biopsy is performed, which may show peribulbar lymphocytic infiltration, resembling a "swarm of bees." Histologic findings can include pigment incontinence in the hair bulb and follicular stelae.

Classification

Alopecia areata can manifest in various forms:

• Diffuse alopecia areata: Hair loss is spread diffusely over the scalp.
• Alopecia areata monolocularis: Baldness in one spot.
• Alopecia areata multilocularis: Multiple areas of hair loss.
• Ophiasis: Hair loss in a wave-like pattern around the head.
• Alopecia areata barbae: Hair loss limited to the beard.
• Alopecia areata totalis: Complete scalp hair loss.
• Alopecia areata universalis: Complete loss of all body hair.

Varying degrees of alopecia areata, along with alopecia totalis.

Treatment

Treatment efficacy is difficult to assess, and spontaneous remission is unpredictable. Triamcinolone injections and 5% minoxidil creams are commonly used, with significant hair regrowth observed in many cases. Corticosteroid injections are also used, especially for small areas or eyebrow hair loss, though their effectiveness is uncertain. Other medications include Elocon ointment, irritants like anthralin, and topical immunotherapy with ciclosporin.

For severe cases, immunosuppressants like methotrexate have shown promising results. Additionally, a gluten-free diet has been effective in cases associated with celiac disease. In June 2022, the FDA approved baricitinib, a Janus kinase inhibitor, for severe alopecia areata. Ritlecitinib was also approved in June 2023. Faecal matter transplants (FMT) have shown potential in reversing alopecia areata by supporting hair growth and even reversing grey hair.

Prognosis

In cases with a small number of patches, hair typically regrows within a few months to a year. More extensive hair loss may either regrow or progress to alopecia totalis or universalis. The condition primarily affects psychological well-being, causing significant changes in appearance and potential social phobia, anxiety, and depression. Patients may also experience aberrant nail formation due to the involvement of keratin.

Epidemiology

Alopecia areata affects 0.1%-0.2% of the population, with a lifetime risk of 1%-2%, and is more common in females. It commonly occurs in otherwise healthy individuals and tends to present in early childhood, late teenage years, or young adulthood. There is a slightly higher incidence of related immune conditions, such as asthma, allergies, and hypothyroidism.

Self-assessment MCQs (single best answer)

What is the initial symptom of alopecia areata?

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Which cells attack hair follicles in alopecia areata?

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Which diagnostic tool shows "yellow dots" and "exclamation mark hairs" in alopecia areata?

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Which form of alopecia areata involves complete loss of scalp hair?

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Which treatment for alopecia areata is a Janus kinase inhibitor approved by the FDA in June 2022?

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What is the lifetime risk percentage of developing alopecia areata?

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Which is not a possible symptom of alopecia areata?

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Which form of alopecia areata is characterised by hair loss in a wave-like pattern around the head?

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In severe cases of alopecia areata, which immunosuppressant has shown promising results?

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What does a biopsy of alopecia areata typically show?

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