History and exam
Key diagnostic factors
common
recent history of immersion in spa water
Recent history of immersion in a hot tub, whirlpools, swimming pool, water slides or spa tub combined with new-onset erythematous papules on the trunk warrants further investigation for Pseudomonas folliculitis. Under-chlorinated water is thought to be associated with the development of hot tub folliculitis.
uncommon
new medication commenced known to be associated with folliculitis
Ingestion of medications that are known to be associated with folliculitis within the past 2 weeks combined with an acute onset of monomorphic follicular eruption in a patient prone to acne strongly suggests drug-induced folliculitis. Drugs that are commonly associated with the development of folliculitis are corticosteroids, lithium, isoniazid, anticonvulsants, corticotropin, androgenic hormones and iodides.
Other diagnostic factors
common
recent history of shaving
Suggests that nicks or cuts of the skin could have served as a port of entry for microorganisms.
umbilicated, flesh-colored papules
Flesh-colored papules that have central umbilication are suggestive of folliculitis secondary to Molluscum contagiosum.
uncommon
papules on one side of the face in the submaxillary area
A male farmer presenting with papules on one side of the face in the submaxillary area or chin is suggestive of tinea barbae.[27]
small, uniform papules and pustules
Small, uniform papules and pustules on the chest, back and shoulders that are highly suggestive of Malassezia folliculitis.[28] Living in a warm climate or being immunocompromised favors this diagnosis.
background erythema
Erythematous papules and pustules against a background of diffuse erythema is suggestive of Demodex folliculitis.
alopecia/scalp scaling
Tinea capitis can present as alopecia with scaling of the scalp and brittle hair breaking off at the surface of the scalp.[26]
erythematous plaques with hemorrhagic crusts in a dermatomal distribution
Varicella zoster folliculitis primarily affects the hair follicles, but clinically presents as erythematous plaques with hemorrhagic crusts in a dermatomal distribution.
Risk factors
strong
trauma, including shaving and extraction
Shaving hairy regions such as the beard, axillae, and groin facilitates infection of hair follicles. It is postulated that shaving introduces a breach in the skin barrier and spreads microorganisms into the shaved regions.
Other manipulation to the hair follicles, such as plucking and waxing, also facilitates folliculitis.[18]
topical corticosteroid preparations
diabetes mellitus
Patients with diabetes have impaired cellular immunity and are susceptible to infection by gram-positive organisms. Staphylococcal folliculitis is seen in greater frequency in patients with diabetes mellitus.[20] Patients with diabetes mellitus have an increased risk of hospitalization for, and complications from, skin and soft tissue infections.[21]
immunosuppression
Immunosuppression increases susceptibility to infection by bacterial, fungal, or viral microorganisms. For example, patients with HIV are more likely to present with necrotizing Herpes simplex folliculitis than other populations.[22] Eosinophilic folliculitis is seen in people with HIV, usually with low CD4+ counts <300 cells/mm³.[2]
The subcutaneous nodular form of Majocchi granulomas is found in immunocompromised hosts, such as those undergoing bone marrow or organ transplantation, and those receiving long-term suppressive therapy for leukemia or lymphoma.[23]
weak
occlusion and perspiration
Folliculitis in intertriginous zones, such as axillae and groin, or seen in the context of diaper dermatitis (nappy rash) or in people who are obese (e.g., rash in abdominal apron) or immunosuppressed should raise the possibility of infection with Candida albicans.[24]
systemic antibiotics
Long-term treatment of acne with systemic antibiotics can present with gram-negative folliculitis with small follicular pustules and abscesses on the cheeks. This can be misinterpreted as acne getting worse.[25]
immersion in under-chlorinated water
Hot tub folliculitis is most commonly caused by Pseudomonas aeruginosa. About 2 to 3 days after immersion in a hot tub, multiple, large, erythematous papules and pustules on the trunk or areas occluded by swimwear tend to emerge. [Figure caption and citation for the preceding image starts]: Hot tub folliculitis due to P aeruginosaFrom the personal collection of Professor Baden, MD [Citation ends].
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