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UV Dermoscopy for the Diagnosis of Pityrosporum Folliculitis

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Case Presentation

We present a case of a 17-year-old girl with a history of disseminated erythematous follicular papules on the upper chest, back, and upper limbs for the past 2 years, accompanied by mild itching and intermittent periods of exacerbation ( Figure 1A ). Upon examination, bright-green fluorescence was observed in the affected follicle using UV-induced fluorescence dermatoscopy (DL5, light 365nm, Dermlite®) ( Figure 1B ). A biopsy of a follicular papule confirmed the diagnosis of pityrosporum folliculits (PF) ( Figure 1C ). After treatment with fluconazole 150 mg/week for 6 weeks, his lesions completely resolved.

Teaching Point

PF is a cutaneous condition secondary to infection of the hair follicle by fungi of the genus Malassezia spp [ 1 ] . This fungus has enzymes, such as lipases and phospholipases, capable of hydrolyzing triglycerides into fatty acids, thereby promoting follicular occlusion [ 1 ] . PF has a universal distribution, predominantly affects young adults, and is associated with antibiotic therapy, diabetes mellitus and immunosuppressants [ 1 ] .

With the advancement of new technologies, dermoscopy combined with UV light has become an effective tool in the investigation of such cases. In this case, the lesions presented with follicle-bound bluish white, as previously described [ 2 ] , associated with the visualization of the central follicular bright green color only seen through the dermoscope with UV light.

We emphasize the importance of dermoscopy combined with Wood lamp in the diagnostic elucidation of this condition and encourage further scientific publications. The visualization of this follicular staining can improve the diagnosis and treatment of these cases.

References

  1. Clinical characteristics and treatment outcomes of Pityrosporum folliculitis in immunocompetent patients Green M, Feschuk AM, Kashetsky N, Maibach HI. Arch Dermatol Res.2023;315(6):1497-1509. CrossRef PubMed
  2. 100 years of Wood’s lamp revised Klatte JL, van der Beek N, Kemperman PM. J Eur Acad Dermatol Venereol.2015;29(5):842-847. CrossRef PubMed

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