Folliculitis

ICD-11

1B74

Synonyms

Bacterial or mycotic folliculitis; infundibulofolliculitis.

Definition

Intrafollicular pyoderma of microbial origin located at the hair follicles.

Aetiology & Pathogenesis

Usually Staphylococcus aureus (coagulase positive), also gram-negative bacteria or Malassezia spp. and other mycotic species. Predisposing factors: mechanical pressure (tight clothing, excoriations, increased humidity and sweating, occlusion by topical products or wound dressings, terminal hair shaving), immunosuppression (HIV, diabetes mellitus, corticosteroids), inadequate hygiene.

Signs & Symptoms

Papules and pustules involving the follicular canal at the acroinfundibulum and infrainfundibulum including surrounding tissue (perifolliculitis) of the hair follicles.

Localisation

Skin with occlusion preferentially chest and back, intertriginous areas and buttocks, suprapubic area, belly folds, scalp and neck.

Classification

1. Ostiofolliculitis: pyoderma of the follicle ostia; often in intertriginous or occluded areas.
2. Folliculitis et perifolliculitis: deeper penetration of infection into the infrainfundibulum with stronger inflammatory reaction and marked perifolliculitis . Final stage with deeper penetration leads to furuncle and involvement of several follicles to carbuncle.
3. Folliculitis barbae: chronic ostiofolliculitis of terminal hair in beard area, often spread by shaving.

Laboratory & other workups

Culture. Blood glucose. In case of severe, widespread disease check immuno-deficiency markers.

Dermatopathology

In superficial folliculitis, neutrophils invading the acroinfundibulum where gram positive and gram negative cocci or hyphae and spores colonize. The deeper the infectious agent penetrating the follicle, the more perifollicular granulocytic neutrophils and mononuclear cells accumulate. Late stage of severe deep folliculitis with granulomatous reaction and scarring repair.

Course

Acute and chronic depending on environment, origin of microbe and immune status of patient.

Complications

Furuncle, carbuncle. Rarely sepsis. Scars.

Diagnosis

Clinical features and microbial culture (bacteria, mycosis).

Differential diagnosis

Other forms of folliculitis with sterile and non-sterile pustules: eosinophilic folliculitis; pustular psoriasis; perforating folliculitis; acrosyringeal pustular eruption; pustular drug eruptions; pseudofolliculitis barbae; pili recurvati or incarnati with secondary foreign body reaction.

Prevention & Therapy

Depending on severity and location, first choice always antiseptics, avoid topical antibiotics. Nasal carriers of gram-negative bacteria treated according to allowed antibiotics Systemic antibiotics in deep disseminated folliculitis and perifolliculitis or carbuncle; topical antimycotics when positive in culture. In deep penetrating and/or widespread mycotic infection systemic azoles.

Change and wash clothing regularly. Avoid humidity. No overwashing of skin, ph-neutral or acidic shower gels.

2.2.4 Folliculitis