Causes of folliculitis include bacterial, fungal, viral, and parasitic microorganisms.
Most commonly superficial and resulting from infection by Staphylococcus aureus; use of antibacterial soaps may suffice as treatment for uncomplicated folliculitis, which is self-limited.
Deeper infection and inflammation of hair follicles from Staphylococcus aureus generally require systemic antibiotic therapy based on culture sensitivities.
Other common infectious agents include gram-negative organisms, fungi, viruses, and parasites.
Folliculitis can occur in patients with acne undergoing long-term oral antibiotic therapy and may mimic an acne flare.
Treatment is tailored to the underlying cause; hygienic measures, MRSA eradication, and symptomatic therapies are other important treatment modalities to consider.
Folliculitis is an inflammatory process involving any part of the hair follicle; it is most commonly secondary to infection. It is important to recognize noninfectious causes of folliculitis (e.g., eosinophilic folliculitis) as well as folliculitis primarily involving the scalp (e.g., folliculitis decalvans).
Folliculitis manifests clinically as erythematous papules or pustules around hair follicles.
Depending on the etiology and chronicity of the condition, histologic examination reveals various populations of inflammatory cells around the pilosebaceous unit.
Folliculitis commonly occurs in areas with terminal hair growth, such as the head and neck region, axillae, groin, and buttocks; it also favors areas under occlusion.
History and exam
Key diagnostic factors
- recent history of immersion in spa water
- new medication commenced known to be associated with folliculitis
Other diagnostic factors
- recent history of shaving
- umbilicated, flesh-colored papules
- papules on one side of the face in the submaxillary area
- small, uniform papules and pustules
- background erythema
- alopecia/scalp scaling
- erythematous plaques with hemorrhagic crusts in a dermatomal distribution
- trauma, including shaving and extraction
- topical corticosteroid preparations
- diabetes mellitus
- occlusion and perspiration
- systemic antibiotics
- immersion in under-chlorinated water
Investigations to consider
- bacterial skin swab
- viral skin swab
- skin scraping for mycology
- tissue culture
- skin biopsy
uncomplicated superficial folliculitis, organism unknown
recurrent/deep folliculitis due to methicillin-susceptible Staphylococcus aureus (MSSA)
recurrent/deep folliculitis due to methicillin-resistant Staphylococcus aureus (MRSA)
hot tub folliculitis due to Pseudomonas aeruginosa infection
Malassezia furfur (Pityrosporum folliculitis)
Demodex folliculorum folliculitis
eosinophilic pustular folliculitis (Ofuji disease)
HIV-associated eosinophilic folliculitis
eosinophilic pustular folliculitis in infancy
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