The white skin spots, due to pityriasis versicolor are usually caused by lipophilic yeast Malassezia furfur (known also as Pityrosporum ovale). Other species include Malassezia globosa, M. obtusa etc. M. furfur is part of our skin's normal microbiota, but what happens so it triggers a health problem? One of the factors necessary for the fungus to cause the disease is when the skin is rich in lipids and moist. Do you already remember why this condition occurs during the warm seasons? Another important factor for its appearance is the general immunological state of the organism. It has been shown that in patients with impaired immunity for some reason, pityriasis is more common.
Which mechanism does the fungus exert to cause white spots on the skin?
The reason pityriasis is called variegated is that the condition can be represented by brown, pink or white spots. Usually a spot of one type is observed in each patient, but cases in which all three colors are present are also described. In addition, the presence of fine scales (scales) determines its categorization as lichen. The condition is usually not itchy.
In brown spots, a microscopic increase in the granules loaded with pigment (melanosomes) in the epidermis is observed. In pink, it is believed that there is a slight inflammation or concomitant course with seborrheic dermatitis I just want to recall that the latter again interfered with M.furfur. The white spots due to a product of yeast metabolism that blocks melanin synthesis. You will not believe that this metabolite is actually my favorite ingredient in cosmetics, namely azelaic acid.
During the examination it is very important to consider all skin conditions that can cause white spots. These are primarily vitiligo, pityriasis alba. Pink spots should be distinguished from pityriasis rosea, seborrheic dermatitis, tinea corporis (fungus of another species) and others.
The diagnosis is made accurately by a correct history, examination with a Wood lamp, examination by KOH (potassium base). A biopsy is usually not needed.
Once diagnosed, systemic and local treatment with antifungal drugs can be performed. Recovery of the pigment of the skin takes months, sometimes a year. It is very important to use sunscreen when exposed outdoors, because this skin is not protected due to the absence of melanin.
If in doubt, even if there is only one spot, see a dermatologist. This will provide timely therapy and the affected areas of the skin will be more limited.