Pityriasis

The word pityriasis describes a type of scaling: fine, small, dry scales that flake off like bran. Under this shared name, however, lie distinct diseases with different causes. Telling them apart matters, because their course and their management are not the same.

Pityriasis rosea of Gibert. This is an acute, self-limiting eruption seen mainly in adolescents and young adults, often in spring and autumn. It is thought to be linked to the reactivation of certain human herpes viruses, but it is not contagious in the usual sense of the word.

• It usually begins with a single larger, round or oval, salmon-pink lesion with a fine collarette of scale just inside the border — the “herald patch”, located on the trunk.
• One to two weeks later a widespread eruption of smaller oval lesions appears, with their long axis running parallel to the skin tension lines, which on the back creates a pattern resembling the branches of a fir tree.
• Itching is usually mild to moderate; some patients report tiredness or a respiratory infection in the days before the rash.
• The eruption clears on its own within six to eight weeks, sometimes more slowly, temporarily leaving lighter or darker patches.

Pityriasis versicolor. This is a superficial mycosis caused by yeasts of the genus Malassezia, which belong to the normal skin flora but can multiply excessively in conditions of heat, humidity and increased sebum production.

• Small round patches appear and merge into larger plaques on the chest, back, shoulders, neck and upper arms.
• The colour varies — hence the name versicolor: lighter patches on tanned skin, browner or pink patches on fair skin.
• Gently scraping the surface produces a characteristic fine scaling.
• Itching is slight or absent, and the cosmetic appearance is the main reason patients seek advice. Depigmented patches may persist for weeks or months after the infection has settled, and recurrences are common in the warm season.

Pityriasis alba. This is seen mainly in children and adolescents, often against a background of dry skin or an atopic constitution.

• It presents as round or oval, poorly defined patches, lighter than the surrounding skin, with very fine scaling.
• The typical sites are the cheeks, the area around the mouth, the arms and the shoulders.
• The contrast becomes obvious in summer, when healthy skin tans while the affected areas stay pale.
• The course is chronic, with periods of remission, but leaves no scarring; the patches fade gradually, sometimes over months or years.

Factors that influence the course. For all these forms, the state of the skin barrier and the environment matter: dry air, excessive washing with harsh soaps, intense unprotected sun exposure, heavy sweating, synthetic clothing, stress and fatigue. In pityriasis versicolor, heat and humidity favour recurrences; in pityriasis alba, dry skin accentuates the colour contrast; in pityriasis rosea, long hot baths and rubbing can intensify the itching.

Why the distinction matters. The appearance of “patches with fine scaling” is also found in other conditions — guttate psoriasis, nummular eczema, seborrhoeic dermatitis, secondary syphilis or drug reactions. For this reason, a correct diagnosis, established at consultation, precedes any therapeutic approach.

At our practice, pityriasis is approached through the Kozak Method — internal and external treatment, individualised, based on consultation. Results differ from one patient to another.