What is Pityriasis versicolor (tinea versicolor)? Fungal Infection of the Skin
10 November 2019
Pityriasis versicolor (PV) is a common fungal infection of the skin. It is frequently termed tinea versicolor, but this is a misnomer as the causal agent is a yeast, not a dermatophyte. The yeasts implicated in PV belong to the genus Malassezia and are normally present on the skin as a part of its microbiome. There are over a dozen different species of Malassezia, but those most commonly found in PV are M. globosa, M. sympodialis and M. furfur. These yeasts are unrelated to food, oral and vaginal yeasts. Because everyone has Malessezia as part of their normal skin flora, it is only when this commensal yeast overgrows that it results in PV.
What are the causes for Pityriasis Versicolor (tinea versicolor)?
It is not precisely known why certain patients develop the condition, but precipitating factors include:
- hot and humid climates;
- excessive sweating;
- oily skin;
- a family history of pityriasis versicolor;
- immunosuppression; and some types of cancer.
Important to know about Pityriasis versicolor (tinea versicolor):
- PV typically affects young people and is more common in men.
- It is not hereditary or contagious, is unrelated to poor hygiene and frequently recurs.
- It typically affects the chest, back, neck and arms.
- The individual lesions are flat or raised, scaly, and can coalesce into confluent plaques affecting large areas of the skin’s surface.
- When exposed to sunlight, the yeast produces azelaic acid, which impedes normal tanning and has a slightly bleaching effect, giving rise to the commonly seen hypopigimented variant of PV. It can also
- present with pink, red or dark scaly lesions. The multiple colours of PV give rise to the name, versicolor.
How is Pityriasis versicolor (tinea versicolor) treated?
- Treatment consists of education, antifungal shampoos, creams and oral antifungal tablets.
- Shampoos containing ciclopirox, ketoconazole, zinc pyrithione or selenium sulphide can be used first line. These shampoos are applied to the affected areas for five to 10 minutes before being rinsed off. This regimen can be repeated twice weekly for four to six weeks and then once every several weeks as a preventive strategy.
- Topical creams containing azoles or ciclopirox have all been used successfully in various regimens of over several weeks. Topical terbinafine has been shown to be effective but is not always predictable in the clinical setting.
- Oral antifungal agents such as itraconazole, fluconazole and ketoconazole are often used to treat extensive or recalcitrant disease over several days with good results (see Table 1). Oral terbinafine is ineffective in the treatment of PV and should be avoided.
Table 1
| Oral antifungal regimensfor the treatment ofpityriasis versicolor | |
| KETOCONAZOLE | 200 mg/dayfor 10 daysor 400 mgsingle dose |
| ITRACONAZOLE | 200 mg/dayfor one week |
| FLUCONAZOLE | 300 mg/week fortwo to fourconsecutiveweeks |
Although the treatments outlined are usually effective in killing the implicated yeast, residual dyspigmentation, usually hypopigmentation, often remains after treatments, and patients need to be made aware this usually improves over time.
