What causes folliculitis along the scalp and neck?

Common Causes of Folliculitis Along the Scalp and Neck

Folliculitis of the scalp and neck is most commonly caused by Staphylococcus aureus infection, but can also result from other bacterial, fungal, viral, and parasitic pathogens, as well as non-infectious causes such as occlusion, irritation, or underlying systemic conditions. 1, 2

Infectious Causes

Bacterial Causes

• Staphylococcus aureus - Most common bacterial cause 3, 4

  • Can lead to superficial folliculitis or deeper infections like furuncles (boils)
  • May progress to involve multiple adjacent follicles (carbuncles), especially on the back of the neck 3
  • Can cause tufted folliculitis, a localized scarring bacterial folliculitis of the scalp 5, 6

• Other bacterial pathogens 2

  • Gram-negative bacteria including Pseudomonas aeruginosa
  • Often misdiagnosed as staphylococcal infection

Fungal Causes

• Dermatophyte fungi - Cause tinea capitis (ringworm of the scalp) 3
  • Most commonly species of Microsporum and Trichophyton
  • Can present as:
    • Kerion - painful, boggy, inflammatory mass with associated alopecia
    • Favus - chronic inflammatory condition with yellow, crusted cup-shaped lesions

Other Infectious Causes

• Viral pathogens
• Parasitic organisms 2

Non-Infectious Causes

Physical/Chemical Factors

• Occlusive hair products or greasy creams 1
• Friction from tight headwear
• Irritation from harsh hair products
• Improper shaving techniques (particularly on the neck) 1

Underlying Conditions

• Folliculitis decalvans capillitii - chronic, progressive, inflammatory condition 7
• Perifolliculitis capitis abscendens et suffodiens - deep inflammatory condition 7
• Lichen planopilaris - inflammatory condition that can present as folliculitis 7
• Eosinophilic pustular folliculitis 7

Risk Factors

• Poor personal hygiene 3
• Diabetes (especially for carbuncles on the back of the neck) 3
• Close personal contact with infected individuals 3
• Nasal carriage of S. aureus (present in 20-40% of the general population) 3
• Sharing personal items like razors or towels 1
• Wearing synthetic materials rather than cotton clothing 1

Diagnostic Considerations

Proper diagnosis often requires laboratory confirmation as clinical appearance alone may be misleading:

• Cytology - Simple, rapid, and inexpensive method to identify causative organisms 2
• Culture - To identify specific bacterial or fungal pathogens 3
• Wood's lamp examination - May show fluorescence in certain fungal infections 3
• Skin biopsy - May be necessary in cases of recurrent or treatment-resistant folliculitis 7
• Dermoscopy - Can help visualize characteristic features like black dot hair stubs or comma-shaped hairs 3

Clinical Pearls

• Folliculitis differs from furuncles in that inflammation is more superficial with pus present in the epidermis, while furuncles extend deeper into the subcutaneous tissue 3
• Recurrent folliculitis may be associated with nasal carriage of S. aureus 3
• What appears as bacterial folliculitis may actually be fungal, viral, or parasitic in origin, leading to treatment failure when only antibacterial therapy is used 2
• The classification of folliculitis is complex, with considerable variability in histologic findings 7

Understanding the diverse causes of folliculitis is essential for proper diagnosis and targeted treatment to prevent complications such as scarring, spreading infection, or progression to deeper tissue involvement.