These hyperpigmented lesions with fine scale on the outer edges are characteristic of pityriasis versicolor, also known as tinea versicolor. These macules (or patches) are commonly found on the trunk, proximal extremities, or neck. The lesions can be hypopigmented (pityriasis versicolor alba), hyperpigmented (pityriasis versicolor nigra), or erythematous (pityriasis versicolor rubra).1 It is common to see hyperpigmentation in people with darker skin tones, as was the case with this patient. Pityriasis versicolor is often asymptomatic, but patients may describe mild to moderate pruritis.
Pityriasis versicolor is a common fungal infection of the superficial layers of the dermis caused by Malassezia furfur.2 Impaired immunity and excessive sweating are risk factors for pityriasis versicolor; other risk factors include having a family member with tinea versicolor and living in a hot, humid region.1 Adolescents and young adults are most often affected.1
An evoked scale sign is a helpful tool to confirm the diagnosis clinically.3 Scale will appear when you stretch the affected skin with your thumb and index finger (or you scrape the area with a scalpel blade).3 If there is doubt about the diagnosis, use a potassium hydroxide (KOH) preparation; a positive test will reveal the classic “spaghetti and meatballs” pattern.1
Selenium sulfide 2.5%, zinc pyrithione 1%, and ketoconazole 2% shampoo are effective topical treatments. The shampoo is applied full strength to the affected skin daily for 5 to 10 minutes before it’s washed off. This can be done for 1 to 4 weeks, with longer treatment courses resulting in higher cure rates. Systemic therapy is reserved for patients with widespread infection or those who do not respond to topical treatment.4 It’s important to advise patients that the restoration of normal skin pigmentation can takes months.
This patient was treated with ketoconazole 2% shampoo for 3 weeks. A complete return of skin color was achieved 6 months after completion of therapy.
Image courtesy of Judy Jasser, MD. Text courtesy of Judy Jasser, MD, Department of Pediatrics, and Daniel Stulberg, MD, FAAFP, Professor and Chair, Department of Family and Community Medicine, Western Michigan University Homer Stryker, MD School of Medicine, Kalamazoo.