A 35-year-old woman presents with a 3-month history of diffuse hair loss, 200–300 hairs/day on counting. She had a severe COVID-19 illness 4 months ago. Trichoscopy shows predominance of telogen hairs. The pathophysiology of this condition is:

• A Synchronised premature shift of anagen follicles to telogen phase due to systemic physiological stress ✓
• B Autoimmune destruction of the hair follicle bulb by T-lymphocytes
• C Miniaturisation of follicles from androgenetic alopecia triggered by COVID-19
• D Scarring alopecia due to follicular destruction by SARS-CoV-2

Explanation

Acute telogen effluvium (TE) following COVID-19 occurs 2–4 months after the precipitating stressor (infection, high fever, surgery, nutritional deficiency, parturition) due to synchronised premature conversion of numerous anagen (growing phase) follicles to telogen (resting phase) — which then shed together. The physiological stress-mediated elevation of inflammatory cytokines and cortisol precipitates this shift. TE is non-scarring, diffuse, self-limiting (6–9 months), and fully reversible. Alopecia areata involves CD8+ T-cell attack on the bulb. Androgenetic alopecia shows patterned miniaturisation.

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.