Contents
Introduction
Pityriasis veriscolor is a type of fungal skin infection. It is typically very superficial, and is caused by the Malassezia group of fungus. It is often asymptomatic, except for a flaky appearance of the skin, often with pale white, brown or pink coloured patches. It may persist for months or even years.
- In light skinned individuals, the patches often look darker than the surrounding skin
- In darker skinned individuals, the patches often appear lighter than the surrounding skin
It differs from the other main types of fungal skin infection tinea and candida as it is caused by a different type of fungus. Tinea is caused by dermatophytes (“ringworm”), candida by … candida(!) whilst pityriasis veriscolor is caused by malassezia.
- Other conditions caused by malassezia include seborrhoea dermatitis and pityriasis capitis (dandruff)
Pityriasis versicolor is more common in hot, humid climates, and in those who sweat heavily.
- “Versicolor” means “variable colours”
- It wa previously called “Tinea versicolor” but this is technically incorrect as tinea refers specifically to the dermatophytes
Clinical Features
- Dry scaly rash
- Well demarcated, often circular patches
- Patches may coalesce into larger affected areas
- Typically affects the trunk
- May also extend to the neck, armpits and groin
- Mainly young and middle aged individuals
- Slow insidious onset – typically gradually worsening over months or years
- Not usually itchy
- Often recurrent – especially it tends to return in summer months
Differential Diagnosis
- Discoid eczema
- Itchy!
- Guttate psoriasis
- Look for scaly lesions elsewhere
- Pityriasis rosea
- Onset often rapid, look for herald patch, often itchy, patches typically pink coloured
- Seborrheic dermatitis
- Often also affects the face and scalp
- Tends to be more scaly than pityriasis versicolor
- Tinea corporis
- Vitiligo
- Completely white patches
Pathology
- Malassezia type funguses, produce acetic acid. This diffuses down through the skins nd affects melanocyte function, and hence the infection causes pale patches on the skin
- Affected patches of skin do not tan
Diagnosis
May be diagnosed clinically, but ideally should be confirmed with skin scrapings.
- Affected areas will fluoresce blue-green on Wood’s lamp examination
- A woods lamp is a UV light (“black light”) used for skin examination
- Potassium hydroxide preparation (KOH) shows clusters of yeast cells and long hyphi. Sometimes called the spaghetti and meatballs appearance
- Malassezia is hard to grow int he lab, and scrapings are often reported as negative
- There are 7 known species of malassezia
- Many unaffected individuals will grow malassezia on skin scrapings
Management
Usually, topical agents are applied for about 2 weeks. The scaling of the skin will typically resolve quite quickly, but it can be several months until the colour of the skin returns to normal.
The “-azoles” (e.g. fluconazole, ketaconazole) are the anti-fungal drugs that are effective against malassezia.
Topical treatments include:
- Selenium sulphide
- ‘Selsun’ yellow shampoo
- Miconazole or ketoconazole shampoo
- Apply shampoos daily for 5-10 days. Wash the affected area, and then leave on for 5 minutes before washing off
- Sodium thiosulphate solution
- Apply and leave on for 10 minutes (or overnight) before washing off
- Oral antifungals
- Fluconazole 400mg one-off dose
- Ketaconazole 200mg daily for 7-10 days
- For recurrent or resistant cases
- Prophylaxis
- May be considered in patients with recurrent cases
- Itraconzaole 200mg monthly
Advise patients to wash with an anti-dandruff shampoo at least twice a week in future to reduce the risk of recurrence.