What causes patchy hair loss in a 4-year-old child?

Patchy Hair Loss in a 4-Year-Old Child

The most likely cause of patchy hair loss in a 4-year-old child is either tinea capitis (scalp ringworm) or alopecia areata, and distinguishing between these two conditions is critical because tinea capitis requires immediate antifungal treatment to prevent spread and permanent scarring, while alopecia areata is an autoimmune condition with high spontaneous remission rates in children. 1

Primary Diagnostic Considerations

Tinea Capitis (Scalp Ringworm)

• Most common infectious cause of patchy hair loss in prepubertal children, particularly in cosmopolitan communities 1
• In the UK, Trichophyton tonsurans accounts for 50-90% of cases 1
• Key clinical features to look for:
  • Patchy hair loss with varying degrees of scaling and erythema 1
  • The scalp may appear inflamed, though signs can be subtle 1
  • "Black dot" appearance (broken-off hair stubs) with endothrix infections 1
  • "Grey patch" with fine scaling in ectothrix infections 1
  • May present as diffuse scaling resembling dandruff 1
  • Painful regional lymphadenopathy may be present 1

Alopecia Areata

• Second most common cause of patchy hair loss in children (26.2% of pediatric hair loss cases) 2
• Key clinical features to distinguish it:
  • Patches of hair loss where the affected skin appears normal or only slightly reddened (no significant scaling) 1
  • "Exclamation mark hairs" (short broken hairs) at the margins of expanding patches 1
  • Smooth, non-inflamed scalp in the bald patches 1
  • Nail involvement in approximately 10% of cases 1

Critical Distinguishing Features

The presence or absence of scalp inflammation and scaling is the key differentiator:

• Tinea capitis: Inflamed scalp with scaling (though may be subtle) 1
• Alopecia areata: Normal-appearing or slightly reddened skin without significant scaling 1

Diagnostic Approach

Physical Examination Priorities

• Examine the scalp carefully for erythema, scaling, pustules, or inflammatory changes 1, 3
• Look for exclamation mark hairs at patch margins (suggests alopecia areata) 1
• Check for "black dots" or broken hair stubs (suggests tinea capitis) 1
• Examine nails for pitting or dystrophy (associated with alopecia areata) 1
• Assess hair pull test at patch margins 3

Dermoscopy/Trichoscopy

• Can significantly improve diagnostic accuracy 1, 3
• In alopecia areata: Yellow dots, exclamation mark hairs, cadaverized hairs 1
• In tinea capitis: Comma hairs, corkscrew hairs, broken hairs 1

Laboratory Testing

• If tinea capitis is suspected: Fungal culture is essential for confirmation and species identification 1
• If alopecia areata is suspected: Usually no investigations needed; diagnosis is clinical 1

Other Important Differential Diagnoses

Trichotillomania

• Hair pulling disorder that can mimic alopecia areata 1
• Distinguishing features: Incomplete hair loss with broken hairs that remain firmly anchored (still in anagen phase) 1
• May coexist with alopecia areata 1

Traction Alopecia

• Related to tight hairstyles or hair accessories 4, 5
• Pattern follows areas of tension 5

Telogen Effluvium

• Diffuse rather than patchy hair loss 1, 4
• History of triggering event 2-3 months prior 4, 2

Management Implications

If Tinea Capitis is Diagnosed

• Requires systemic antifungal therapy (topical treatments are insufficient) 1
• Treatment prevents spread to others and permanent scarring 1
• Immediate treatment is essential 5

If Alopecia Areata is Diagnosed

• Spontaneous remission occurs in up to 80% of children with limited patchy hair loss of short duration (<1 year) 1
• Observation without treatment is a legitimate option for many patients 1
• Treatment options for children are limited due to tolerability concerns 1
• Psychological support and counseling are important components of management 1

Common Pitfalls to Avoid

• Do not assume all patchy hair loss is alopecia areata without examining for signs of infection 1, 5
• Do not miss tinea capitis by failing to look for subtle scaling or inflammation 1
• Do not treat suspected tinea capitis without fungal culture confirmation when diagnosis is uncertain 5
• Do not use aggressive treatments for alopecia areata in children given high spontaneous remission rates and treatment tolerability issues 1

When to Refer

• Immediate referral if: Diagnosis is uncertain, treatment is failing, or there is evidence of scarring alopecia 5
• Consider dermatology referral for: Extensive alopecia areata, kerion (boggy inflammatory mass), or atypical presentations 1, 5