A 23-year-old man went to his family physician (FP) for treatment of a pruritic rash on his upper trunk and upper arms. A week earlier, he’d been seen at an urgent care center for the rash and given a one-week course of doxycycline 100 mg twice daily. The antibiotic hadn’t helped. The patient had many papules and pustules surrounding the hair follicles on his upper chest, upper arms, back, and neck.
What's your diagnosis?
The FP suspected that this could be Pityrosporum folliculitis because of the cape-like distribution and the lack of response to an antibiotic. While bacterial folliculitis is more common than Pityrosporum folliculitis, this condition is not rare. Pityrosporum is also known by the name Malassezia furfur, a yeast-like fungal organism.
A KOH preparation was performed, but no evidence of Pityrosporum was found. This was not suprising. While a KOH preparation for tinea versicolor is usually positive for a “spaghetti and meatballs” pattern seen with Pityrosporum, this is not always the case with Pityrosporum folliculitis because the yeast lives deeper in the hair follicle, rather than on the surface of the skin.
The patient was desperate for a definitive diagnosis and rapid treatment, so he was happy to undergo a punch biopsy around an involved hair follicle.
The FP began treatment with ketoconazole 2% shampoo to be applied daily to the hair and the involved areas while in the shower. In 10 days, the patient returned for the biopsy results, which confirmed the presence of Pityrosporum in the hair follicles. The patient didn’t notice any improvement with topical treatment, so the FP started the patient on oral fluconazole 200 mg/d for 2 weeks and the Pityrosporum folliculitis resolved. Typically, Pityrosporum folliculitis and/or tinea versicolor can be treated with systemic antifungals, topical azoles, and/or shampoos containing azoles, selenium, or zinc.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R, Hunter-Anderson K. Folliculitis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:680-685.