Pathology of Folliculitis
Folliculitis is an inflammatory process
distributed around hair follicles and involving follicular opening or
adjacent perifollicular skin.
Patients with depressed immune system, diabetes mellitus and obesity have a greater risk of contracting folliculitis.
Common sites for folliculitis are scalp, face, thigh, legs and buttock.
Superficial- (usually suppurative)- Bacteria, fungus, syphilis, virus.
Deep- (usually granulomatous)-
Fungi or bacteria
Superficial- (usually suppurative)- Acne vulgaris, rosacea, follicular mucinosis, steroid induced.
Deep- (usually granulomatous)- Acne vulgaris- conglobata & keloidal forms and perforating form.
Deep- (scarring) folliculitides- Folliculitis decalvans ; Folliculitis keloidalis nuchae.
Spongiotic- Fox fordyce disease, atopic dermatitis,
pruritic folliculitis of pregnancy.
Predominantly lymphocytic- Lichen planopilaris, pityriasis rubra pilaris.
Predominantly granulomatous- Rosacea, dermatitis perioralis.
The most common cause of folliculitis is infection by bacteria, staphylococcus aureus.
Other infective folliculitis include Pseudomonas folliculitis (hot-tub folliculitis).
This is characterised by dense collection of polymorphs in pilar canal and prominent perifollicular lymphocytic infiltration.
Gram (-) folliculitis caused by Klebsiella or Enterobacter (usually around nose), Pityrosporum folliculitis, tinea capitis and tinea barbae causing folliculitis (fungal infection caused by candidial species and dermatophytes).
Eosinophilic pustular folliculitis is usually seen in HIV positive patients.
Herpetic folliculitis caused by Herpes simplex virus may produce vesicles and pustules in the beard area of men.
Folliculitis in a case of dermatophyte infection
Syn: Acne Rosacea
Grade I- Erythematous telangiectatic
Grade II- Papular /papulopustular
In some cases granulomatous infiltrate is present.
Intact or fragmented Demodex is sometimes present.
Occurs mostly during adolescence.
Usual sites are face and upper half of
Grade I Comedones-
Black heads (open follicles)
White heads (closed follicles)
III Nodulocystic (conglobata)-
There is foreign body (granulomatous) reaction to the follicular contents.
If collection of polymorphs is small and superficial a pustule results.
If the collection is large and deep a nodule forms.
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