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Trichorrhexis Nodosa — SCE Dermatology MCQ

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HardHair DisordersTrichorrhexis NodosaSCE Dermatology

A 42-year-old woman presents with trichorrhexis nodosa. Microscopic examination of the hair shaft shows small white nodes where the hair fractures easily. The cortex shows a 'broomstick' fracture pattern. What is the most common cause?

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Correct answer: D — Acquired damage from chemical treatments or excessive heat styling

The best answer is “Acquired damage from chemical treatments or excessive heat styling”. The diagnosis follows the defining morphology, distribution, histopathology and time course; management changes when red flags, scarring, systemic disease or malignancy risk are present. The alternatives “Genetic hair shaft disorder, after clinicopathological correlation”, “Thyroid disease, after specialist assessment, when the full phenotype supports it”, “Alopecia areata, when the full phenotype supports it”, “Iron deficiency, within an appropriate UK pathway” are clinically adjacent possibilities, but they do not fit the defining morphology, distribution, histopathology, risk signal or management sequence in this stem.

Reference: British Association of Dermatologists clinical resources: https://www.bad.org.uk/