Author: Dr Ian Coulson, Consultant Dermatologist and Editor-in-Chief, 2022.
Edited by the DermNet content department
This 26-year-old woman is concerned about spots on her back. They are not particularly itchy or painful, but their presence limits the kind of clothing she can wear. She would like for them to clear up before her forthcoming wedding. She also has scaling on the nasolabial folds and scalp.
The image shows monomorphic papules over the interscapular area. There are no comedones, and there is no variety in the size and shape of lesions as one sees in acne. These features all suggest Malassezia (pityrosporum) folliculitis. The condition results from the overgrowth of pityrosporum yeasts within the hair follicles.
Humidity, heat, seborrhoea, immunosuppression, and HIV contribute to the overgrowth of the yeasts. The back is the most frequently affected area; it can also occur on the chest. It is often associated with seborrhoeic dermatitis in other sites.
Routine bacteriology from affected follicles is negative as the causative yeasts require very specialised culture media to grow them. They are most easily visualised on biopsy.
Topical antifungals such as selenium sulfide shampoo, or azoles such as econazole lotion or ketoconazole shampoo, can be helpful both in initial treatment and recurrence prevention. Oral fluconazole or itraconazole are sometimes more convenient to use.
