🩺 Exam finding: Circular area of non-scarring alopecia found incidentally in an adult. Alopecia areata is a chronic autoimmune condition causing patchy hair loss and sometimes nail involvement. It affects around 1–2% of the population and may occur at any age, including childhood. 🧑‍🦱➡️🕳️

📘 About

Alopecia areata (AA) is an organ-specific autoimmune disease that targets hair follicles.
Characterised by patchy, well-circumscribed hair loss on the scalp or other hair-bearing areas.
May also affect nails (pitting, ridging, trachyonychia) in up to 20% of cases.
Course is unpredictable - some regrow hair spontaneously, others have chronic or relapsing disease.

🧬 Aetiology & Pathophysiology

T-cell–mediated autoimmune attack on the hair bulb of anagen follicles.
Causes premature transition to catagen/telogen phase → shedding of hair.
Genetic predisposition (HLA-DR, CTLA4) with environmental triggers such as infection, stress, or trauma.

🤝 Associations

Other autoimmune diseases – thyroid disease, vitiligo, pernicious anaemia, type 1 diabetes.
Atopy – eczema, asthma, allergic rhinitis.
Chromosomal syndromes – Down and Turner syndromes.

🔎 Clinical Features

Round or oval bald patches with smooth, normal-looking skin (non-scarring).
Exclamation mark hairs – short, broken hairs tapering near the scalp margin (diagnostic clue).
Can affect scalp, beard, eyebrows, eyelashes, or body hair.
Nail changes: pitting, ridging, rough nails (trachyonychia).
Variants:
- Alopecia totalis – total scalp hair loss.
- Alopecia universalis – loss of all body hair.
- Ophiasis – band-like pattern along the occiput and temples.

⚠️ Poor Prognostic Factors

Childhood onset.
Extensive or recurrent disease.
Ophiasis pattern.
Nail involvement.
Family history or coexisting autoimmune disease.

🧪 Investigations

Diagnosis is clinical - based on pattern and morphology of hair loss.
Blood tests if indicated:
- TSH and thyroid antibodies – for thyroid disease.
- FBC, ferritin – to assess general health.
Dermoscopy: yellow dots, exclamation mark hairs, black dots (broken hairs).

💊 Management

Limited disease: potent topical corticosteroids (e.g. clobetasol) or intralesional triamcinolone.
Extensive disease: topical immunotherapy (e.g. diphencyprone), JAK inhibitors (baricitinib, ruxolitinib) under specialist supervision, or phototherapy.
Supportive: wigs, camouflage fibres, eyebrow microblading, and psychological support.
Spontaneous regrowth occurs in ~50% within 1 year, but relapses are common 🔄.

📊 Prognosis

Variable course - may relapse or resolve spontaneously.
Better prognosis with adult-onset, limited disease, and no nail changes.
Poor prognosis with early onset, extensive disease, or associated autoimmunity.

📚 References

💡 Teaching tip: Always check for nail changes and thyroid function in alopecia areata. The presence of exclamation mark hairs and a normal, non-inflamed scalp help differentiate it from fungal or scarring alopecias.

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Alopecia Areata