Hair Disorders in Children

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Hair Basics - Tiny Follicle Facts

  • Hair Cycle (Pediatric): Phases:
    • Anagen (active growth): 2-6 yrs, ~85-90% hairs.
    • Catagen (involution): 2-3 wks, <1%.
    • Telogen (resting): 2-3 mths, ~10-15%; then Exogen (shedding).

    ⭐ Newborn anagen phase is shorter, leading to physiological telogen effluvium (hair shedding in first few months).

  • Classification: Etiology (Congenital/Acquired), distribution (Localized/Diffuse), scarring (Scarring/Non-scarring).
  • Diagnostic Approach:
    • History: Onset, duration, pattern, family hx, systemic symptoms, hair care.
    • Clinical Exam: Scalp (inflammation, scale), Hair Pull Test (>10% hairs = positive), specific hair signs (exclamation (!) mark hairs, black dots, broken hairs).
    • Wood's Lamp: For Microsporum spp. (green fluorescence) in Tinea Capitis.
    • Trichoscopy: Non-invasive. AA (yellow/black dots, ! hairs), Tinea Capitis (comma, corkscrew, barcode hairs), Trichotillomania (varied length broken hairs, flame hairs).
    • Scalp Biopsy: For scarring alopecias, diagnostic uncertainty.

Trichoscopy patterns for common alopecia types

Non-Scarring Alopecias - Patchy Problems Parade

⭐ 'Exclamation mark' hairs (short, broken, proximally tapering) are pathognomonic for Alopecia Areata.

  • Alopecia Areata (AA): Autoimmune; well-demarcated patches; ophiasis pattern (band-like loss at scalp margins). Trichoscopy: yellow dots, black dots, broken hairs. Rx: Topical/intralesional corticosteroids, minoxidil, anthralin. Severe: Systemic steroids, JAK inhibitors.
  • Tinea Capitis: Fungal infection. India: T. violaceum, T. tonsurans. Ectothrix/Endothrix. Types: Black dot, grey patch, kerion (boggy, inflamed), favus (cup-shaped scutula). Dx: KOH, culture. Rx: Griseofulvin 20-25 mg/kg/day for 6-8 weeks; Terbinafine (if T. tonsurans).
  • Telogen Effluvium (TE): Diffuse shedding ~3 months post-trigger (fever, stress, ↓nutrition). Positive hair pull test (>10% hairs in telogen). Reassurance, address trigger.
  • Trichotillomania (TTM): Compulsive hair pulling. Bizarre patterns, varied hair lengths. Trichoscopy: perifollicular hemorrhages, v-sign, flame hairs. Rx: SSRIs, behavioral therapy.
  • Traction Alopecia: Due to tight hairstyles. 'Fringe sign' (sparing of short hairs along frontal/temporal hairline). Reversible early; later, scarring. Rx: Looser hairstyles.

Traction Alopecia with fringe sign

ConditionEtiologyKey Clinical FeaturesDiagnostic CluesManagement Pearls
Alopecia AreataAutoimmuneSmooth, circular patches; exclamation mark hairsTrichoscopy: yellow/black dots, broken hairsCorticosteroids, minoxidil
Tinea CapitisDermatophyte (Trichophyton, Microsporum)Scaling, broken hairs, black dots, kerion, favusKOH microscopy, fungal cultureGriseofulvin, Terbinafine
Telogen EffluviumStress, illness, nutritional deficiencyDiffuse shedding, positive hair pull testHistory of triggerReassurance, address underlying cause
TrichotillomaniaPsychiatric (impulse control)Irregular patches, hairs of different lengths, bizarre shapesTrichoscopy: fractured hairs, perifollicular hemorrhageBehavioral therapy, SSRIs
Traction AlopeciaProlonged tension from hairstylesHair loss at hairline/partings, 'fringe sign'History of tight hairstylesAvoid tight hairstyles, topical minoxidil if chronic

Hair Shaft & Scarring - Strand & Scar Stories

Hair Shaft Defects:

DefectMicroscopic AppearanceKey Associations
Trichorrhexis Nodosa'Brush-like' fractureTrauma, genetic (e.g., argininosuccinic aciduria)
MonilethrixBeaded hair, elliptical nodesAD (KRT81, KRT83, KRT86)
Pili TortiTwisted hair (180° along axis)Menkes disease, Bjornstad syndrome
TrichothiodystrophySulfur-deficient brittle hair, 'tiger tail' (polarizing)BIDS/PIBIDS syndromes, photosensitivity
  • Congenital Alopecias:
    • Aplasia Cutis Congenita (ACC): Localized skin absence, often scalp; membranous type with 'hair collar' sign. Aplasia Cutis Congenita with hair collar sign
  • Scarring Alopecias (Rare in Children):
    • Irreversible follicular destruction (e.g., Lichen Planopilaris, Folliculitis Decalvans).
  • Growth/Color Disorders:
    • Hypertrichosis: ↑Hair growth (non-androgenic). Pediatric causes: drugs (minoxidil), syndromes.
    • Hirsutism: ↑Male-pattern hair (androgenic). Pediatric causes: CAH, PCOS, tumors.
    • Poliosis: Localized white hair patch. Associations: Piebaldism, Waardenburg, Tuberous sclerosis.

⭐ Menkes kinky hair syndrome, an X-linked recessive disorder of copper metabolism, presents with Pili Torti, sparse hypopigmented hair, and severe neurodegeneration.

High‑Yield Points - ⚡ Biggest Takeaways

  • Tinea capitis (often T. tonsurans) is the most common pediatric alopecia.
  • Alopecia areata presents with exclamation mark hairs and non-scarring patches.
  • Telogen effluvium: diffuse shedding 2-3 months post-trigger (e.g., fever).
  • Traction alopecia results from chronic tension from tight hairstyles.
  • Trichotillomania: compulsive hair pulling leading to bizarre hair loss patterns.
  • Loose anagen syndrome: easily, painlessly pluckable anagen hairs, common in fair-haired girls.
  • Netherton syndrome: key feature is trichorrhexis invaginata (bamboo hair).

Practice Questions: Hair Disorders in Children

Test your understanding with these related questions

A child comes with a circular 3cm x 3cm scaly patchy hair loss with itching in the lesions. The investigation of choice is

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Flashcards: Hair Disorders in Children

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Collodion babies can later develop _____, where membrane shedding is followed by development of white scales in background of erythematous skin

TAP TO REVEAL ANSWER

Collodion babies can later develop _____, where membrane shedding is followed by development of white scales in background of erythematous skin

congenital ichthyosiform erythroderma

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