Acne or Pityrosporum Folliculitis? Can Dermoscopy Help Diagnose?
Pityrosporum folliculitis, which is caused by naturally-occurring Malassezia yeasts, is a common condition especially in tropical countries. However, because it is easily confused with acne vulgaris, appropriate treatment can be delayed.
A recent letter in response to a review article published in Journal of the American Academy of Dermatology (JAAD) detailed a small study where the authors used dermoscopy to distinguish between the two conditions. The authors state that in an observational study of 15 patients, scaling, which is a distinguishing characteristic for Pityrosporum folliculitis was first seen in 5 patients. After dermoscopy using a universal serial bus (USB) dermatoscope, scaling could be seen in 11 cases. In addition, dermoscopy revealed the presence of folliculocentric papules and pustules with surrounding erythema in all cases.
The authors note that while the pathogenesis of Pityrosporum folliculitis is not yet fully understood, studies suggest it may be an infection of the hair follicle by the Malassezia yeast. In this study dermoscopy showed keratosis pilaris-like features where the hair follicle was seen to be coiled/looped with surrounding erythema and scaling, and hypopigmentation of the involved hair shaft was also observed.
The authors conclude that because dermoscopy revealed aspects of the infections that would not be confused with acne, dermoscopy is a useful tool in distinguishing between the two conditions.