Summer discolored skin patches: what are these?

As the weather is getting warmer and the sun is shining ever brighter, some of us might find strange white spots on their skin. Although the patches are usually asymptomatic, sooner or later they get visually so disturbing, that the affected person decides to turn to a dermatologist. At these times, he/she gets the odd-sounding diagnosis: pityriasis versicolor. Seeing the puzzled face, the dermatologist adds: sun fungus.

It may sound a bit strange having yeast growing on your skin, but that in itself isn’t the problem. Everyone has yeast (or, in fact, fungus) on their skin. So before you go throwing all your sheets, duvet covers and pillowcases in the bin: pityriasis versicolor is not contagious.

The fungus which causes this type of skin disorder is called Malassezia furfur. Usually malassezia grow sparsely in the seborrhoeic areas (scalp, face and chest) without causing a rash. It is not known why they grow more actively on the skin surface of patients prone to pityriasis versicolor. Skin symptoms arise more often in oily skin and in warm climates, and affect people that perspire heavily. So in Hungary you will mainly see it in the summer.

Pityriasis versicolor is very easy to recognise: the coppery brown or pink or pale patches affect the trunk, neck, and/or arms, and are uncommon on the other parts of the body. Sometimes the patches start scaly and brown, and then resolve through a non-scaly and white stage. The white or hypopigmented type of pityriasis versicolor is thought to be due to a chemical (azelaic acid) produced by the yeast that diffuses into the upper layer of the skin and impairs the function of melanocytes.

Mild pityriasis versicolor is treated with topical antifungal agents. It is important to mention that the scalp has to be treated as well, because malassezia also lives on this area. If the scalp is left untreated the chance of recurrence within a short period is very high. Most of these agents are over-the-counter: eg. Selsun blue shampoo, Nizoral shampoo, Mycosolon ointment, Caneste cream. The medicine should be applied widely to all the affected areas before bedtime for as long as directed (usually 3 days and about two weeks, depending on the extent of the rash). Oral antifungal agents are used to treat extensive skin symptomes or if the topical agents have failed.

Those who want to be patch free need to have patience. Once treated the scaliness usually disappears after a few days but the patches often remain visible for longer, even though the skin is ”clear”of the yeast.

The frustrating thing about pityriasis versicolor is that if you are prone to it, it is likely to return. Once the patches have cleared up make sure you protect yourself properly in the sun, don’t apply oily ointments or creams onto your skin (this encourages the yeast to grow) and always dry your skin thorouhhly after showering, bathin, etc.