Alopecia areata
Alopecia areata is an autoimmune condition causing hair loss, typically presenting as discrete bald patches on the scalp and potentially affecting all hair-bearing areas.
Variants of Alopecia Areata
- Alopecia Totalis: Complete scalp hair loss.
- Alopecia Universalis: Total body hair loss.
- Ophiasis: Bandlike pattern of hair loss.
- Ophiasis Inversus: Reverse bandlike pattern.
- Diffuse Alopecia Areata: Widespread thinning.
Prevalence and Demographics
- Lifetime Risk: About 2%.
- Affected Groups: Children and adults of all skin/hair colors, with peak incidence in the second and third decades of life.
Risk Factors
- Chromosomal disorders (e.g., Down syndrome).
- Polyglandular autoimmune syndrome type 1.
- Other autoimmune conditions (e.g., vitiligo, thyroid disease).
- Family history of alopecia areata.
- Specific susceptibility genes.
Pathogenesis
- Involves loss of immune privilege in anagen hair follicles, leading to autoimmune attack.
- Supported by perifollicular T cell infiltrates observed in histopathology.
- Strong genetic component with at least 16 risk loci identified.
Clinical Presentation
- Patterns of Hair Loss:
- Most common: Patchy alopecia areata.
- Others: Alopecia totalis, universalis, ophiasis, sisaipho, and diffuse alopecia areata.
- Features: Exclamation point hairs, localized tingling/itching, potential regrowth of unpigmented hairs.
- Nail Changes: Pitting, ridging in 10–40% of patients.
Diagnosis
- Primary Diagnosis: Clinical.
- Diagnostic Tools:
- Trichoscopy may reveal specific features (e.g., exclamation point hairs, yellow dots).
- Hair pull test and skin biopsy can aid diagnosis.
Differential Diagnosis
- Trichotillomania.
- Tinea capitis.
- Telogen effluvium.
- Androgenetic alopecia.
- Discoid lupus erythematosus.
Treatment
- No Cure: Treatment aims to speed up hair regrowth or camouflage hair loss.
- Mild Cases: Intralesional corticosteroids, topical treatments (corticosteroids, minoxidil, anthralin).
- Extensive Cases: Topical immunotherapy, systemic corticosteroids, JAK inhibitors.
- Other Treatments: Dupilumab, methotrexate, platelet-rich plasma, micro-needling.
- Camouflage Options: Wigs, hairpieces, and styling products.
Prevention
- Currently, no known preventive measures for alopecia areata.
Prognosis
- Course: Unpredictable; spontaneous regrowth common but relapses possible.
- Progression:
- 5–10% of cases progress to totalis or universalis with low likelihood of recovery.
- Poor Prognosis Factors: Early onset, extensive disease, nail dystrophy, ophiasis pattern, comorbid autoimmune diseases.
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