Pityrosporum folliculitis is an under-recognized eruption of the face and upper portion of the trunk that may be confused with, or occur simultaneously with, acne vulgaris.

We sought to characterize risk factors for Pityrosporum folliculitis, its clinical presentation, and its response to treatment.

A retrospective chart review was performed on all patients age 0 to 21 years seen at our facility from 2010 to 2015 with Pityrosporum folliculitis confirmed by a potassium hydroxide preparation.

Of 110 qualifying patients, more than 75% had acne that had recently been treated with antibiotics, and when recorded, 65% reported pruritus. Clinical examination demonstrated numerous 1- to 2-mm monomorphic papules and pustules that were typically on the forehead extending into the hairline and on the upper portion of the back. The most common treatment was ketoconazole shampoo, which led to improvement or resolution in most cases. Some patients required oral azole antifungals.

This study was retrospective and relied on providers describing and interpreting the clinical findings and potassium hydroxide preparations. No standard grading system was used.

Unlike classic acne vulgaris, Pityrosporum folliculitis was more common after antibiotic use. It presented as fine monomorphic, pruritic papules and pustules along the hairline and on the upper portion of the back, and it improved with topical or oral azole antifungal therapy.