The skin is the first line of defense against pathogenic microorganisms and this is why fungal infections like Pityriasis versicolor are one of the most frequent reasons for dermatological consultations.
First of all, note that a large number of microorganisms populate the skin surface and these are part of the normal microbiota. These are harmless under normal conditions but could cause infections under certain circumstances.
What exactly is Pityriasis versicolor?
This fungal skin infection, also known as Tinea versicolor, is due to a fungus of the Malassezia genus. According to some studies, the most frequent etiological agent may vary depending on the geographical location. M. globosa is responsible in temperate countries and M. furfur in tropical ones.
This condition equally affects people from all walks of life and has a worldwide distribution. However, the infection is more frequent in countries with warm humid climates. This is because these conditions favor colonization of this kind of fungus on the skin.
The most affected people tend to be young and there’s a peak incidence between the ages of 20 and 40 years old. The causal agent colonizes the skin without causing any damage; however, it could proliferate under certain conditions and lead to infection.
Causes
As mentioned above, the infection is due to a fungus of the Malassezia genus, common in the skin. In fact, Malassezia furfur has been isolated in 95% of the areas with abundant sebaceous glands in various individuals.
The fungus colonizes in these areas because it needs fats for nourishment. Thus, some factors that can alter the fatty composition of the skin will make the microorganism proliferate. In this way, the number of strains of the fungus will increase.
In this respect, these situations can promote the appearance of Pityriasis Versicolor:
- A hot humid climate
- Excessive sweating and wearing tight clothing
- Pregnancy
- Oily skin
- Use of corticosteroids
In addition, a deficiency in the immune system and the administration of antibiotics can also promote the disease. Both situations affect the control mechanisms with which the human body prevents the proliferation of pathogens.
Symptoms of Pityriasis versicolor
The main characteristic of this infection is the appearance of oval-shaped macules – scaly patches on the skin. These spots may be lighter or darker than the surrounding tissue and are either brown, brownish, or white.
These patches may appear anywhere on the body, although most commonly on the back, neck, chest, and upper third of the arm. They may appear in the skin folds and people can easily mistake them for psoriasis.
In addition to the patches, the infection is usually asymptomatic, although there may be itching under certain circumstances — sweating, for example. Note that Pityriasis versicolor is neither painful nor contagious but causes great psychological discomfort in those afflicted by it.
Diagnosis
This is actually quite simple. Dermatologists can make an accurate diagnosis just by looking at the skin patches. However, this condition could be mistaken with other skin conditions — such as seborrheic dermatitis.
There are various tests to make a differential diagnosis, although the most common one is direct observation under a microscope. In this respect, they’ll take a sample of the cutaneous scales of the lesions, add potassium hydroxide to them, and examine them under the microscope.
On certain occasions, a culture of the sample may be necessary for the sole purpose of differentiating between the types of Malassezia that might be causing the infection.
Treatments for Pityriasis versicolor
As we mentioned above, this is a fungal infection, and so antifungals are the treatment of choice. According to medical sources, shampoos and creams are effective in most cases. Thus, doctors should reserve systemic treatment for patients with recurrence and failure of the usual approach.
As for topical treatment, the use of creams, gels, or shampoo with ketoconazole or ciclopirox has proven effective. In addition, the use of 2.5% selenium sulfide shampoo is beneficial. The skin patches usually disappear within 1 to 2 weeks in most cases.
Systemic treatment should be used in cases where topical treatment isn’t effective. In this respect, fluconazole, ketoconazole, or itraconazole can be taken orally for a given period of time.
How to prevent Pityriasis versicolor?
Although it’s caused by a fungus that lives on the skin, there are several measures that can be taken to prevent the appearance of this disease. Most of the preventive advice is oriented towards maintaining proper personal hygiene and reducing the amount of oil on the skin.
In addition, keep in mind that Pityriasis versicolor is recurrent. So, the oral intake of antifungals is recommended in the warm months with prior medical authorization if you’ve previously been afflicted by it.
