Pityriasis versicolor is a fungal infection of the superficial layer of the epidermis caused by fungi of the Malassezia genus. These fungi are considered part of the normal skin microbiota, especially on the scalp and upper trunk.

Factors such as humidity, heat, hormonal changes, a weakened immune system and oily skin (increased sebum production) promote the growth and pathogenic activity of the fungus. For this reason, pityriasis often occurs in patients who sweat excessively. The most commonly affected areas are the chest, back, back of the neck, and upper arms.

The condition presents as light red, yellowish or brownish round or oval patches with a smooth or slightly scaly surface, clearly demarcated from the surrounding healthy skin. Lesions may merge and affect larger areas of the trunk and back. Due to contrast with surrounding skin, lesions often appear lighter in summer and darker in winter. Itching is usually mild.

Suspicion is based on medical history and clinical presentation and the diagnosis is confirmed by microbiological analysis of a skin sample, typically through microscopic examination.

In most cases, treatment is local. After bathing, affected areas should be gently rubbed with a rough towel, and once the skin is dry, antifungal creams should be applied.

In generalized cases, oral antifungal therapy may be required. Even after successful treatment, skin discoloration may persist for several weeks or months.

Preventive measures include avoiding synthetic clothing, not wearing clothes previously worn by others and maintaining regular hygiene of the skin and scalp.