What is folliculitis decalvans?
Folliculitis decalvans is a relatively rare, chronic, recurring inflammatory condition of the hairy scalp that leads to permanent scarring hair loss (primary cicatricial alopecia). The main features are follicular pustules (small pus-filled spots around the hairs), redness, crusting and erosions, and pain or itch, with gradually expanding areas of scarred, hairless skin. Once scarring hair loss has developed it is irreversible, so the aim of treatment is to suppress the inflammatory activity and prevent further spread.
A characteristic sign is tufting (polytrichia): several hairs that appear to emerge like a small brush from a single follicular opening. This is frequently seen in folliculitis decalvans and has given rise to the term “tufted folliculitis”.
What causes it?
The cause is not fully understood. The bacterium Staphylococcus aureus and an abnormal host response are often mentioned. In early lesions the inflammation involves activation of the immune system and mediators that promote the recruitment of white blood cells (neutrophils) and, over time, scarring.
Conditions it can resemble
Several other scalp conditions can look similar, and distinguishing them is important because treatment differs:
- Dissecting cellulitis (perifolliculitis capitis abscedens et suffodiens) — deep nodules and abscesses with interconnecting tracts, often at the back of the head.
- Acne keloidalis nuchae — papules, nodules and keloid-like plaques on the neck and occiput; pustules are less prominent.
- Lichen planopilaris / frontal fibrosing alopecia — scaling around the follicles and redness, usually without neutrophilic pustules.
- Discoid lupus erythematosus of the scalp — redness, scaling, follicular plugging and pigment change; a biopsy may be needed to distinguish it.
- Tinea capitis (scalp fungus) — scaling, broken hairs and swollen glands; confirmed with a fungal test.
- Ordinary folliculitis or boils without scarring; and erosive pustular dermatosis of the scalp in older people on sun-damaged skin.
How is it diagnosed?
The diagnosis is based on the clinical picture together with trichoscopy (magnified examination of the scalp), which shows loss of the follicular openings, tufted hairs, redness around the follicles, and pustules or crusts. A swab of a pustule is often taken for culture (frequently growing S. aureus) and to test which antibiotics will work, particularly before combination antibiotic treatment or when the condition keeps returning. A fungal test may be done to rule out tinea capitis. When there is doubt or the presentation is atypical, a scalp biopsy is taken — preferably from the active edge — to confirm scarring inflammation of the follicles.
Treatment
There is no single proven “standard treatment”; treatment is tailored to the disease activity, extent and pattern of recurrence, and usually combines local anti-inflammatory therapy with antibiotics, with retinoids or immune-modulating drugs reserved for resistant disease.
General and topical measures
- Explanation that the scarring hair loss is irreversible; avoiding mechanical irritation (scratching, tight hairstyles); gentle hair care.
- Antiseptic shampoo as supportive care.
- Topical antibiotics (such as mupirocin or clindamycin lotion) for limited pustules or as maintenance, especially when a staphylococcal component is suspected.
- Topical or injected (intralesional) corticosteroids to reduce inflammatory activity and symptoms.
Systemic antibiotics (first choice in active disease)
- Tetracyclines (for example doxycycline 100 mg once daily) for their anti-inflammatory effect, often for several weeks to months depending on response.
- The classic combination of rifampicin plus clindamycin (typically 300 mg twice daily of each for about 10 weeks), noting drug interactions, possible liver effects and bowel side effects.
- Other antibiotic strategies (such as minocycline or clarithromycin) guided by culture and clinical picture in recurrent or resistant cases.
Retinoids and other options
- Isotretinoin for refractory or recurrent disease; long remissions have been described, though relapse after stopping can occur.
- Dapson and, in severe resistant cases handled by specialists, immune-modulating drugs may be used, with appropriate monitoring.
- Selected procedural options such as photodynamic therapy, and — very exceptionally — surgery or radiotherapy for otherwise untreatable disease.
When to see a doctor
See a dermatologist if you have recurring pustules, crusting, redness or pain on the scalp, or if you notice expanding bald patches where the scalp looks smooth and scarred, or several hairs emerging from one opening. Because the hair loss becomes permanent, early treatment to control the inflammation offers the best chance of limiting further scarring.