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Differentiating Pityrosporum Folliculitis and Acne

J Am Acad Dermatol; ePub 2017 Nov 11; Prindaville, et al

Unlike classic acne vulgaris, Pityrosporum folliculitis was more common after antibiotic use, according to a recent study. It presented as fine monomorphic, pruritic papules and pustules along the hairline and on the upper back and improved with topical or oral azole antifungal therapy. A retrospective chart review was performed on all patients aged 0 to 21 years seen from 2010-2015 with Pityrosporum folliculitis confirmed by potassium hydroxide (KOH) preparation. Researchers found:

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

Citation:

Prindaville B, Belazarian L, Levin NA, Wiss K. Pityrosporum folliculitis: A retrospective review of 110 cases. [Published online ahead of print November 11, 2017]. J Am Acad Dermatol. doi:10.1016/j.jaad.2017.11.022.

Commentary:

This article is interesting and relevant. It is probable that many patients with pityrosporum folliculitis may be diagnosed incorrectly with acne and subsequently managed for acne. The clinical presentation can be similar, with papules and pustules on the forehead, along the hairline, and on the upper back. While it can develop as a result of the treatment of acne, especially with antibiotics, the presence of pruritus may also suggest pityrosporum folliculitis. Dermatologists should consider this diagnosis in patients who fail to respond to traditional therapies. If monomorphous lesions do develop, consider therapy with azole antifungals. Perhaps having our acne patients wash the affected areas with ketoconazole shampoo would be helpful, both for prevention and treatment of pityrosporum folliculitis and as a secondary benefit to help manage concomitant seborrheic dermatitis, which is often also present in patients with acne.

—Diane S. Berson, MD, FAAD

Associate Professor, Department of Dermatology, Weill Medical College of Cornell University, New York, NY
Assistant Attending Dermatologist, New-York Presbyterian Hospital, New York, NY

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