Overview
Also known as tinea versicolor, pityriasis versicolor is a fungal infection of the skin caused by Malassezia furfur, resulting in a chronic, non-inflammatory disorder characterised by macular patches that vary in pigmentation (hence the name ‘versicolor’).
It usually affects the trunk and is seen in hot and humid climates, such as in returning travellers.
Pathophysiology
Since Malassezia species require the presence of lipids to grow (lipophilic), they grow in areas rich in sebum, as it can provide fatty acids and triglycerides. As a result, they tend to grow in the upper trunk, flexures, and scalp. As they grow, an acid produced by the fungus causes depigmentation.
Epidemiology
- Pityriasis versicolor is more common in hot and humid climates
- It is more common in adolescents and young adults, as their sebaceous glands are more active
Risk Factors
- Warm, humid environments – as this favours fungal proliferation
- Causes of increased sebum production – such as hyperhidrosis, tight-fitting clothing, ointments, and creams
- Immunodeficiency – such as HIV and immunosuppressive drugs
- Diabetes mellitus
Presentation
Features
Features of pityriasis versicolor include:
- Macules on the trunk and proximal limbs with varying pigmentation
- Their colours can range from pale, pink, to brown or red
- They are non-pruritic and often have associated powdery scale
- They can coalesce and form scaly plaques
Management
Overview
- 1st-line: topical ketoconazole shampoo – this is the most effective for covering large areas
- If ineffective: send skin samples for culture and microscopy and offer oral itraconazole
Prognosis
- Changes in pigmentation may take 2-3 months to resolve with treatment
- Spontaneous resolution without treatment is uncommon
- Recurrence is common and may occur in up to 6/10 people in their first year
