The Use of Dermoscopy to Distinguish Between Pityrosporum Folliculitis and Acne Vulgaris

Background: Both Pityrosporum folliculitis (PF) and Acne vulgaris (AV) are chronic inflammations of pilosebaceous follicles but with different etiologies. Similar findings may lead to a misdiagnosis that worsens symptoms, especially if PF is treated with antibiotics meant for AV. A simple kalium hydroxide (KOH) examination helps to differentiate PF and AV, but it is not always readily available in a clinical setting. Purpose: To find an alternative, practical tool to confirm the diagnosis of PF and AV. Review: The dermoscopy is a handheld microscope equipped with 10x magnification and a light source for microscopic visualization of the subcutaneous structures. The monomorphic lesions in PF appear as hypopigmented, round lesions with coiled/looped hair in the center. Dermoscopy images of AV vary according to their polymorphic manifestations. A non-inflammatory AV shows a yellow-brown blockage in the center, while an inflammatory AV is depicted as round, whitish lesions with thin brownish borders and erythematous marginal lesions. Pustular AV appears as raised lesions with indistinct borders, white or yellowish in the middle, and surrounding reddish borders. Conclusion: Dermoscopy helps to see skin structures invisible to the naked eye and thus helps to diagnose PF and AV.