scalp folliculitis

introduction

scalp pustules are a relatively common problem and often recurrent
there are many causes and the various conditions can be divided in to those causing superficial pustules or vesicles vs those causing deeper granulomas

superficial folliculitis

vesicular or papulovesicular:
- Herpes simplex virus (HSV)
- herpes zoster (shingles)
- molluscum contagiosum
- eczema herpeticum
pustular:
- recurrent scalp folliculitis / “acne necrotica miliaris” (may also affect face)
  - poorly understood pruritic condition which is mainly due to Cutibacterium acnes but also there may be a role for yeasts (Malassezia species) and mites (Demodex folliculorum)
  - unlike the more severe cicactrical acne necrotics variant below, it leaves no scars, is confined to the scalp, and is characterized by extremely itchy vesiculopustular lesions
  - probably has genetic and environmental predispositions
  - Rx is anti-dandruff shampoos (may be helpful), topical antibiotics (eg. clindamycin, fusidic acid gel) +/- steroids +/- oral antihistamines +/- short courses low dose cefalexin 500-1000mg/d +/- oral long term docycycline +/- low dose oral isotretinoin
    - Cutibacterium acnes is generally more sensitive to doxycline than cefalexin and resistance development appears to be low
    - A topical foam formulation of minocycline was approved for use in acne by the FDA in the US in 2019 and may be an option in the future
    - there may be an as yet unproven role for nicotinamide orally or topically ¹⁾
  - a severe cicatrical form is called acne necrotica / acne varioliformis / necrotizing lymphocytic folliculitis
    - this is usually recurrent papules mainly on the margins of the scalp which can become pustular with depressed centers and develop black haemorrhagic crusts which last for 3-4 weeks and may leave permanent pox-like scars
    - thought to begin as lymphocytic folliculitis, which were triggered by Cutibacterium acnes and perhaps an abnormal inflammatory response to this bacteria or to Staph aureus
    - usually begins in the third decade of life or later and lacks comedones
    - mechanical manipulation of pre-existing lesions, such as rubbing and scratching, may aggravate the disease, but not a cause - doxepin can be considered for patients who excoriate and manipulate lesions
    - Rx is doxycycline 100mg po once daily plus topical steroids and usually needs to be continued for weeks or months but some do not respond ²⁾
      - however doxycycline, especially at 100mg/d appears to increase risk of resistance organisms, especially Staph. epidermidis - more so than short courses of cefalexin ³⁾ which is also beneficial for this condition
    - once control is achieved, antibacterial or antiseptic lotions may substitute systemic antibiotics or isotretinoin as prophylaxis to prevent possible relapse
    - if Staph. auerus is found then appropriate antibiotics and nasal carriage clearance is suggested
  - a rare severe form is perifolliculitis capitis abscedens et suffodiens which mainly affects black adult men
- acne vulgaris
- acne rosacea
- other bacterial folliculitis
  - most often caused by Staphylococcus aureus, streptococcus, proteus, pseudomonas or coliform bacilli
  - especially if hyperhidrosis, macerated skin, depilation, topical steroids, chemicals or immunocompromise eg. HIV / AIDS, diabetes mellitus
  - may become a deep furuncle or carbuncle
- toxic erythema of the newborn
- pruritic folliculitis of pregnancy
- dermatophytes
  - Microsporous ringworm tinea of the scalp (great gray patch tinea)
    - large round patches with satellite patches, hairs break at 4-6mm, fluoresce under Wood's lamp
  - Trichophytic ringworm tinea of the scalp (black dots tinea)
    - multiple small alopecic areas with black dots of hair follicle broken at skin surface
- candida
- Pityrosporum
  - superficial pustulosis which most frequently affects the back and the upper part of the thorax
- chemical or mechanical trauma
- acneiform eruptions
  - corticosteroids
  - halogens
  - topical hydrocarbons
  - lithium carbonate
- pseudofolliculitis
  - mainly in black men when curly beard hairs are cut too short, they may curve back into the skin and cause inflammation
- keratosis pilaris atrophicans
  - hair keratosis
  - pseudopelade
- keratosis follicularis spinulosa decalvans
  - usually X-linked recessive, rarely AD ⁴⁾
  - causes cicatricial alopecia of the scalp and eyebrows during infancy or adolescence
- lichen planopilaris
  - mainly women 30-60yrs old, mainly front or occipital
- pityriasis rubra pilaris
  - generally accompanies or precedes seborrheic dermatitis of the scalp
  - yellow-orange erythematosquamous plaques, often developing on the scalp, with obvious islands of sparring and palmoplantar hyperkeratosis.
- eosinophilic pustular folliculitis (Ofuji’s syndrome)
  - recurrent episodes of eruptive sterile follicular papulopustules in seborrheic areas (including face, neck, trunk as well as scalp), accompanied by leukocytosis and eosinophilia on biopsy. Many cases have mild eosinophilia, mild rise in IgE and reduced IgG and IgA on blood tests.
  - classic form: more common in Japan; chronic and recurrent with individual lesions typically last more than 1-2 weeks, and relapse every 3-4 weeks but no systemic symptoms. 70-90% respond well to NSAIDs such as oral indomethacin (25–75 mg/day). Refractory cases may require UV Rx or otehr Rx.
  - immunosuppression-associated type of EPF - eg. HIV, leukaemia, etc
  - infantile form - most resolve by age 3yrs
  - in cases where the torso and palms are affected, consider L-tryptophan-induced form with eosinophilic-myalgia syndrome
  - medication induced EPF eg. allopurinol, timepidium bromide, carbamazepine, indeloxazine hydrochloride, minocycline, paroxetine, etizolam, maprotiline ⁵⁾
- follicular mucinosis
  - follicular papules and indurated plaques associated with alopecia
  - accompanied with mycosis fungoides and angiolymphoid hyperplasia with eosinophilia, less frequently with chronic discoid lupus erythematosus and Goodpasture’s syndrome
- follicular mycosis fungoides
  - infiltrated follicular papules located on the face, neck, trunk and extremities, and sometimes on the scalp
- perifolliculitis capitis abscendens et suffodiens
  - severe destructive folliculitis with sinus tracts and fistulae leading to scarring alopecia
  - often part of the acne inversa spectrum
  - almost exclusively in young men
  - ?role of Gram negative infections
- secondary syphilis (rare)
- folliculitis decalvans (rare)
  - causes tufting of hair so it looks like a toothbrush and eventually scarring and cicatricial alopecia
- genetic immunodeficiencies
  - recurrent and persistent pyoderma, folliculitis, keratitis, and atopic dermatitis with defective leukocyte and lymphocyte function and response to antihistamines (H1)⁶⁾

deep folliculitis generally with granulomas

acne vulgaris
acne inversa group of follicular occlusion conditions
- acne conglobata
- dissecting cellulitis of the scalp
- hidradenitis suppurativa
  - rare familial form which affects the post-auricular region ⁷⁾
staph furuncle/carbuncle
tinea barbae
sycosis
favus
- folliculitis caused by T. schoenleinii and is currently prevalent in Spain
kerion Celsi
- starts as tinea tonsurans
demodicosis
- excessive amount of Demodex mites
lupoid rosacea
acne conglobata
perforating folliculitis
halogens
lithium carbonate
acneiform syphilis
folliculitis sclerotisans nuchae (keloidal folliculitis)
- mainly on the neck and mainly dark skinned males