Malassezia folliculitis / pityrosporum folliculitis
Definition:
- An infection of the pilosebaceous unit caused by lipophilic Malassezia yeasts, particularly M. globosa, M. sympodialis, and M. restricta.
- Malassezia yeasts are normal skin flora but can cause disease under specific conditions.
Associated Conditions:
- Seborrhoeic dermatitis
- Pityriasis versicolor
Who Gets Malassezia Folliculitis?
- Most commonly affects adolescent and young adult males.
- Risk Factors:
- Hot, humid climates
- High sebum production
- Hyperhidrosis (excessive sweating)
- Occlusion from emollients and sunscreens
- Antibiotic use
- Immunosuppression (topical and oral steroid use, HIV)
Clinical Features:
- Presents as small, uniform, itchy papules and pustules, mainly on the upper back and chest.
- Other affected areas: forehead/hairline, chin, neck, and extensor aspects of the upper limbs.
- Distinguished from acne vulgaris by the absence of comedones.
- Examination:
- Wood lamp may show yellow-green fluorescence.
- Dermoscopy features:
- Papules and pustules based on hair follicles
- Perifollicular erythema
- Perilesional scale
- Hypopigmented and coiled/looped hairs
Diagnosis:
- Primarily clinical.
- Laboratory Investigations:
- Skin scraping, tape stripping, swab, or biopsy.
- Potassium hydroxide preparation may reveal budding yeasts (hyphae are rarely seen).
- May-Grünwald-Giemsa stain (less common).
- Special media required for culture.
- Histopathology may show yeast within hair follicles and surrounding dermis.
Differential Diagnosis:
- Acne vulgaris
- Steroid acne
- Bacterial folliculitis
Treatment:
- Address predisposing factors to prevent recurrence.
- Topical Treatments:
- Selenium sulfide shampoo
- Econazole solution
- Topical ketoconazole
- Maintenance therapy with weekly application.
- Oral Treatments:
- Fluconazole (preferred due to better side effect profile)
- Itraconazole (less commonly used)
- Other Treatments:
- Isotretinoin (used in recalcitrant cases)
- Photodynamic therapy (PDT)
Prevention:
- Recurrence is common.
- Long-term prophylaxis with topical agents for high-risk individuals or those with multiple recurrences.
- Periodic re-evaluation of predisposing factors is recommended.
