Alopecia areata

What is alopecia areata?

Alopecia areata is a type of non-scarring alopecia that presents as sudden, well-defined hair loss in patches, which may be single or multiple and, in some patients, may coalesce or progress to more extensive involvement. 

It is a relatively common condition, affecting around 1–2% of the population and can occur at any age, from childhood to adulthood, with a variable course characterised by periods of activity and remission. 

Signs and symptoms of alopecia areata

It typically occurs as well-defined patches that are usually asymptomatic, although some patients may report mild itching (pruritus), a sensation of tightness or discomfort preceding hair loss. 

Causes of alopecia areata

It occurs following an immune reaction against the hair follicle itself. This is an autoimmune response mediated by T lymphocytes that target the hair follicle during the growth (anagen) phase. Genetic predisposition, the presence of other autoimmune diseases and emotional stress all play a role in the condition. 

Diagnosis of alopecia areata

The key diagnostic test for alopecia areata is trichoscopy. This technique can identify the following features:

• Exclamation mark hairs: these are thinner at the base and thicker at the tip, indicating follicular damage. 
• Yellow dots: follicular openings filled with sebum and keratin debris.
• Black dots: remnants of hairs broken at the level of the scalp. 
• Short regrowing hairs: a sign of follicular activity.

These findings help determine the stage of the disease and the degree of inflammation. 

Treatment of alopecia areata

Treatment is tailored to the extent and severity of the alopecia. It may include anti-inflammatory medications injected directly into the affected area (intralesional corticosteroids) or potent topical therapies for localised lesions, as well as systemic anti-inflammatory medications (systemic corticosteroids) in more extensive cases. 

In recent years, drugs known as JAK inhibitors, such as baricitinib and ritlecitinib, have been developed and have demonstrated efficacy in controlling the immune attack on the hair follicle and promoting hair regrowth.