According to Rook’s Textbook of Dermatology, folliculitis decalvans is a general term for various syndromes in which clinically evident chronic folliculitis leads to progressive scarring. It is a chronically progressive disorder of the hair-bearing areas on the scalp that leads to scarring, alopecia and atrophy.
Tufted folliculitis is a variant of folliculitis decalvans where cirmuscribed areas of scalp inflammation heal with scarring characterized by tufts of up to 15 hairs emerging from a single orifice. The tufts consist of a central anagen hair surrounded by telogen hairs, each arising from independent follicles, converging towards a common dilated follicular infundibulum.
Affected areas of the scalp develop bogginess or induration with pustules, erosions, crusts, scale.
The cause of folliculitis decalvans is still uncertain. Staphylococcus aureus may be grown from the pustules. It has been suggested that folliculitis decalvans may be the result of an abnormal host response to toxins released from Staphylococcus aureus.
In the vast majority of people who develop a bacterial pustular folliculitis of the scalp it is transient, resolves with antibiotics and heals without scarring. However, in some patients, the folliculitis is more persistent, penetrates more deeply within the hair follicle, tends to recur in the same site after apparently successful treatment with antibiotics and produces a scarring alopecia. Spread tends to only occur to neighbouring follicles so that the condition presents as a slowly enlarging solitary area of cicatricial alopecia.
It is still uncertain whether Staphylococcus aureus infection is the primary or secondary process.
Histology reveals follicular abscesses, with a dense perifollicular polymorphonuclear infiltrate, and scattered eosinophils and plasma cells. Foreign-body granulomas occur in response to follicular disruption, which is succeeded by scarring. Eventually all that remains of the follicle is extensive fibrosis.
Men may be affected from adolescence onwards, whereas women tend not to develop this condition until their thirties. Following a pustular folliculitis of the scalp, usually one, but occasionally more, rounded patches of alopecia develop, each surrounded by crusting and a few follicular pustules. Successive crops of pustules appear and are followed by progressive desctruction of the affected follicles.
A scalp biopsy is required to confirm the diagnosis and swabs should be taken of any pustules and the fluid should be cultured. Diagnosis of fungal kerion, lichen planopilaris, chronic cutaneous lupus should be ruled out.
Source: Tony Burns, Stephen Breathnach, Neil Cox, Christopher Griffiths. Rook’s Textbook of Dermatology 2010