Importance:

Pityriasis versicolor generally clears satisfactorily with treatment but often recurs when conditions are suitable for malassezia to proliferate. It recurs when the weather becomes warm and humid again. Regular use of topical treatment minimizes this risk. The color may persist for weeks or months, particularly the hypopigmentation, and it however does not indicate treatment failure.

Pityriasis versicolor is caused by mycelial growth of fungi of the genus Malassezia.

Clinical features of pityriasis versicolor:

Pityriasis versicolor affects the trunk, neck, and/or arms, and is uncommon on other parts of the body. The patches may be brown, palerthan surrounding skin, or pink.

Pale patches may be more common in darker skin; this appearance is known as pityriasis versicolor alba.

Sometimes the patches start scaly and brown, and then resolve through a non-scaly and white stage.

Pityriasis versicolor is usually asymptomatic, but in some people it is mildly itchy.

In general, pale or dark patches due to pityriasis versicolor do not tend to be more or less prone to sunburn than surrounding skin.

Hyperpigmented, hypopigmented, and pink pityriasis versicolor are usually seen as distinct variants but may sometimes co-exist. Pink pityriasis versicolor may also co-exist with seborrhoeic dermatitis as both are associated with malassezia overgrowth.

Diagnosis

Pityriasis versicolor is usually diagnosed clinically. The following tests may be useful.

• Wood lamp (black light) examination — yellow-green fluorescence may be observed in affected areas
• Microscopy of a skin scraping (using potassium hydroxide (KOH) to remove skin cells) — hyphae and yeast cells that resemble spaghetti and meatballs
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Treatment of pityriasis versicolor

Topical measures

Mild pityriasis versicolor is treated with topical antifungal agents.

Topical azole shampoo (ketoconazole shampoo): The medicine should be diluted with little water to apply widely to the skin from the jawline down and left on the skin for 5-15 minutes before rinsing off in the shower. This should be done daily for one week then weekly for one month.

Systemic measures

Oral antifungal agents, itraconazole and fluconazole, are used to treat pityriasis versicolor when extensive or if topical agents have failed.

Preventative measures

Reapplication of a topical treatment such as ketoconazole shampoo every month once the rash has cleared will usually prevent recurrence.