Scalp Folliculitis

Inflammation of the hair follicles of the scalp, appearing as pustules and papules. Causes include bacterial, fungal, parasitic and inflammatory disease.

• Causes:
  • Staphylococcus aureus (the commonest, including MRSA).
  • Malassezia folliculitis and seborrhoeic dermatitis with follicular pustules.
  • Demodex folliculitis.
  • Dermatophyte infection (tinea capitis, kerion).
  • Folliculitis decalvans: a chronic scarring neutrophilic folliculitis of the vertex and crown, with tufted hairs, in young and middle aged adults.
  • Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens): deep nodules and sinuses, mostly in Black men aged 20 to 40.
  • Acne keloidalis nuchae: firm papules and keloid like plaques on the nape of the neck, associated with close shaving and tight collars, mostly in men of African descent.
  • Eosinophilic pustular folliculitis (HIV, or in Japanese patients), erosive pustular dermatosis of the scalp (older people with sun damage and prior trauma).
  • Irritant or occlusive causes: hair oils, pomades, braiding, hats and helmets, and shaving.
• Risk factors: diabetes, obesity, immunosuppression, nasal staphylococcal carriage, close shaving, poor hygiene and humid conditions.

• Superficial infection: small follicular pustules and papules, 2 to 5 mm, on a red base, with itch or tenderness and a hair at the centre. They heal without scarring.
• Deep infection: tender nodules, boils (furuncles), and abscess, with crusts and sometimes lymphadenopathy.
• Folliculitis decalvans: pustules, crusts, and bleeding, with scarring alopecia and tufts of 5 to 20 hairs emerging from a single dilated follicle.
• Dissecting cellulitis: fluctuant boggy nodules that connect through sinus tracts and discharge pus, causing scarring alopecia.
• Malassezia: itchy monomorphic papules and pustules with scale at the frontal margin and scalp.
• Red flags: fever, rapidly spreading cellulitis, scarring with permanent hair loss, a boggy kerion like mass in a child (tinea), and widespread eruption in an immunocompromised patient.
• Differential diagnosis: tinea capitis, seborrhoeic dermatitis, psoriasis, acne vulgaris, impetigo, herpes zoster, lichen planopilaris, discoid lupus, pediculosis, folliculitis keloidalis, Langerhans cell histiocytosis in children, and cutaneous lymphoma.
• Complications: abscess, scarring alopecia, keloid, secondary cellulitis, bacteraemia (rare), and psychological distress.

• Clinical examination of the scalp, hairline and nape, with dermoscopy (tufted hairs, perifollicular scale and erythema, yellow dots).
• Swab pus for bacterial culture and sensitivities (MRSA), and perform potassium hydroxide preparation and fungal culture of plucked hairs and scales.
• Nasal swab in recurrent staphylococcal disease. Check HbA1c or fasting glucose and consider HIV testing in persistent, severe or eosinophilic disease.
• Skin biopsy (4 mm punch, including a hair follicle, with horizontal sections) when scarring alopecia, an unusual pattern, or lack of response is present.
• Ultrasound for deep nodules and tracts.

• General measures: wash the scalp with an antiseptic or medicated shampoo, avoid oils and pomades, avoid tight headwear, stop picking, and do not share combs, hats or towels. Wash pillowcases and hats at 60 C.
• Mild superficial bacterial folliculitis:
  • Chlorhexidine 2 to 4% wash, left on for 3 to 5 minutes, daily for 5 to 7 days then 2 to 3 times weekly.
  • Benzoyl peroxide 5 to 10% wash daily (bleaches fabric).
  • Mupirocin 2% ointment 3 times daily for 5 to 7 days, or clindamycin 1% lotion twice daily for 4 to 8 weeks.
• Moderate, extensive or deep disease:
  • Flucloxacillin 500 mg orally 6 hourly for 7 to 14 days (child 12.5 to 25 mg/kg 6 hourly).
  • Cefalexin 500 mg orally 6 hourly for 7 to 14 days.
  • Doxycycline 100 mg orally 12 hourly for 7 to 14 days (not in pregnancy or under 8 years).
  • Suspected or proven MRSA: co-trimoxazole 160/800 mg orally, 1 to 2 tablets 12 hourly, or clindamycin 300 to 450 mg orally 8 hourly.
  • Drain fluctuant lesions.
• Recurrent staphylococcal folliculitis: decolonise with mupirocin 2% to each nostril twice daily for 5 days, and chlorhexidine 4% body and scalp wash daily for 5 to 14 days. Wash bedding and clothes hot. Treat close contacts who are carriers.
• Malassezia folliculitis: ketoconazole 2% shampoo, left for 5 minutes, 2 to 3 times weekly for 4 weeks, then weekly. For extensive disease, itraconazole 200 mg orally daily for 7 to 14 days, or fluconazole 100 to 200 mg daily for 2 to 4 weeks.
• Demodex folliculitis: ivermectin 1% cream once daily for 8 to 12 weeks, or permethrin 5% cream, with metronidazole 0.75% gel (evidence limited). Oral ivermectin 200 micrograms/kg as a single dose, repeated at 1 week, has been used in resistant cases.
• Tinea capitis and kerion: oral antifungal treatment (terbinafine 250 mg daily for 2 to 4 weeks for Trichophyton, griseofulvin microsize 20 to 25 mg/kg daily for 6 to 8 weeks for Microsporum), as dermatophytes are not cured by topical therapy alone.
• Folliculitis decalvans (specialist care, long term control):
  • Doxycycline 100 mg orally 12 hourly for 3 months, or lymecycline 408 mg daily.
  • Clindamycin 300 mg and rifampicin 300 mg orally 12 hourly for 10 weeks, a regimen with high remission rates (rifampicin interacts with many drugs, including oral contraceptives, warfarin and antiretrovirals, and needs liver monitoring).
  • Topical clobetasol 0.05% or intralesional triamcinolone acetonide 10 mg/mL (0.1 mL per site, up to 20 mg in total) for inflammatory nodules, and topical tacrolimus.
  • Isotretinoin 0.5 mg/kg per day for 6 months or more is used for refractory disease, with strict pregnancy prevention.
• Dissecting cellulitis: isotretinoin 0.5 to 1 mg/kg per day for 4 to 6 months or more (the most effective, as a prolonged therapy), plus doxycycline 100 mg 12 hourly. Adalimumab 80 mg then 40 mg every week or alternate weeks is used in refractory disease. Surgical excision or laser hair removal for end stage disease.
• Acne keloidalis nuchae: avoid close shaving and friction, apply clobetasol 0.05% twice daily, inject triamcinolone acetonide 10 to 20 mg/mL into papules and plaques every 4 to 6 weeks, give doxycycline 100 mg 12 hourly for 3 months, laser hair removal or surgical excision for large keloid plaques.
• Special groups:
  • Pregnancy: use mupirocin, clindamycin topical, cefalexin, flucloxacillin or clindamycin orally. Avoid doxycycline, isotretinoin, and oral azoles.
  • Children: use topical antiseptics and weight based oral antibiotics, with careful exclusion of tinea capitis.
  • Diabetes: control glucose and treat early.
  • Immunosuppression: take cultures early and treat longer.
• Follow up: review at 2 weeks and then monthly for chronic disease. Refer to dermatology if there is scarring alopecia, no response in 4 weeks, or disease needing isotretinoin or biologic therapy.