The skin is the first barrier against pathogenic microorganisms. Fungal infections are one of the most frequent reasons for requesting a dermatological visit and among these pityriasis versicolor is quite common.
First of all, it should be specified that a great variety of microorganisms live on the skin, as part of the normal flora. They are not normally harmful, but they can cause infection when certain conditions occur.
What is pityriasis versicolor?
It is a fungal infection of the skin caused by a fungus of the genus Malassezia . According to some clinical studies, the etiological factor varies depending on the geographical area. In countries with a temperate climate, for example, the most common variety is usually Malassezia globosa , while in tropical countries M. furfur .
Pityriasis versicolor affects all social groups equally and is distributed throughout the world. However, it is more common in countries with a hot and humid climate, climatic conditions that favor the proliferation of the fungus on the skin.
Young people are most affected, with a high peak incidence between 20 and 40 years of age. The pathogen usually lives on the skin without causing damage, but in some conditions it proliferates and causes disease.
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What are the causes?
The infection is caused by the fungus of the genus Malassezia, which usually lives on the skin. The Malassezia furfur was isolated in 95% of the areas of the body where there are abundant sebaceous glands.
The fungus lives in these areas of the body as it needs lipids or fats to feed itself. The factors that are able to alter the adipose composition of the skin can favor the proliferation of the microorganism. Among these conditions we find:
- Hot and humid climate.
- Excessive sweating and tight clothing.
- Oily skin.
- Use of corticosteroids.
A weak immune system and taking antibiotics can also promote the onset of the disease. Both situations compromise the body’s control mechanisms against the proliferation of pathogens.
Symptoms of pityriasis versicolor
The infection is characterized by the appearance of oval-shaped macules or spots on the skin and a slight peeling. They may be lighter or darker than the surrounding tissue and become brown, dark, or whitish.
The spots can appear anywhere on the body, although it is more common to see them on the back, neck, chest, and upper arm. However, in other cases they appear in skin folds, which leads to confusion between pityriasis and psoriasis.
Apart from the spots, the infection usually has no other symptoms, although it does sometimes cause itching, especially when sweating. It is important to note that pityriasis is not painful or contagious, but it can cause discomfort or self-esteem issues.
Identifying pityriasis versicolor is quite simple. The dermatologist is able to provide an accurate diagnosis by observing the spots alone. However it can be confused with other skin conditions, such as seborrheic dermatitis.
Among the tests indicated to perform a differential diagnosis, the most common is direct observation under the microscope. In this case, a scraping of the skin scales of the lesion is performed to which potassium hydroxide is added; finally, they are observed under the microscope. On the other hand, a culture of the sample serves to differentiate the Malassezia strain concerned.
Since it is a fungal infection, antifungals are the treatment of choice. According to research, the application of shampoos and creams is effective in most cases. Systemic treatment should be reserved for relapses or in case of failure of the topical approach.
In topical treatment, the use of creams, gels or shampoos with ketoconazole or ciclopirox has been shown to be effective. In most cases, the spots on the skin usually disappear after a week or two. The application of a 2.5% selenium sulfide shampoo is also helpful.
On the other hand, if topical treatment is not effective, one should switch to systemic treatment. Fluconazole, ketoconazole or itraconazole can be taken orally for some time.
Can it be prevented?
Although it is caused by a fungus that lives on the skin, some measures can help prevent the disease from appearing . Most are aimed at maintaining proper personal hygiene and reducing skin oiliness.
Infin, it is worth remembering that pityriasis versicolor tends to recur over time. For those who have already suffered from it in the past, an oral antifungal treatment is recommended in the hot months, following the doctor’s instructions.