Pityriasis Versicolor

Definition/diagnostic criteria Pityriasis versicolor is a common, benign, superficial fungal infection of the skin, caused predominantly by Malassezia species. It primarily affects the stratum corneum, leading to hypo- or hyperpigmented, scaly patches on the skin. The condition is characterised by its chronic, recurrent nature.

Epidemiology The prevalence of Pityriasis versicolor is higher in hot and humid climates but it is also encountered in the UK. It affects individuals of all races and ages, although it is most common in adolescents and young adults. It has a slight male predominance.

Diagnosis
Clinical features: Patients typically present with well-demarcated, scaly patches, which can be hypopigmented, hyperpigmented or erythematous.

• The lesions primarily appear on the upper trunk, neck, and upper arms.
• Asymptomatic scaling is a common feature, and itching, when present, is usually mild.
• Variation in colour can be more pronounced with sun exposure, as the affected areas do not tan normally.
• Altered pigmentation can be more noticeable for individuals with darker skin.

Investigations: Diagnosis in primary care is usually made on clinical features alone. Skin scrapings may be considered if the diagnosis is uncertain or initial treatment in primary care has failed.

Treatment Pityriasis versicolor can be treated with a 5-day course of ketoconazole shampoo – applied daily for 3-5 minutes before washing off. Alternatively, selenium sulfide shampoo can be used as a lotion. Topical imidazole antifungals such as clotrimazole and miconazole, or topical terbinafine are alternatives, but large quantities may be required.

If topical therapy fails, or if the infection is widespread, pityriasis versicolor is treated systemically with a triazole antifungal.

Prognosis Pityriasis versicolor is a benign condition, and the prognosis is generally excellent. However, recurrence is common, particularly in immunocompromised individuals and patients may require repeated treatments or even maintenance therapy. Pigmentation changes can take several months to resolve, and this can cause distress to some patients.