Pityriasis versicolor !
A harmless, very common yeast infection that causes light, pink or brown scaly patches on the chest and back, more often in hot, humid places.
Updated 2026-11-01
Structures involved
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Microorganisms that cause it
Why it happens
- Phenylalanine and tyrosine metabolism
- Keratinocytes, melanocytes, Langerhans and Merkel cells
- Skin: epidermis layers, dermis, hypodermis
What it is
A chronic, recurrent superficial fungal infection of the stratum corneum caused by Malassezia yeasts, which are part of the normal skin flora. It is also called tinea versicolor, although it is not a dermatophyte infection, and it is not contagious.
Who gets it
Common in adolescents and young adults, when sebum production is highest. It is especially frequent in tropical and humid climates, such as the Colombian coasts and lowlands, where it can affect a large share of the population, and it flares in hot seasons.
Causes
- Malassezia species (M. globosa, M. furfur, M. sympodialis) changing from yeast to the mycelial form
- Heat, humidity and sweating
- Oily skin and use of oily products
Risk factors
- Hot, humid climate and heavy sweating
- Adolescence and young adulthood
- Oily skin or oily skin products
- Corticosteroid use or immunosuppression
- Pregnancy and malnutrition (less often)
- Family history
Pathophysiology
Malassezia depends on skin lipids, so it lives in sebum-rich areas. In heat and humidity it switches to a hyphal form that grows in the stratum corneum. It produces azelaic acid, which inhibits tyrosinase in melanocytes and causes hypopigmentation, and other metabolites that can darken the skin or cause mild inflammation; the fine scale reflects infection of the outer horny layer.
Classification
- Hypopigmented form (most common in darker or tanned skin)
- Hyperpigmented form (light brown to dark brown patches)
- Erythematous form (pink patches)
- Inverse form in skin folds (uncommon)
Symptoms and signs
- Round or oval patches that join into larger areas on the upper trunk, neck and upper arms
- Colour that may be lighter, darker or pinker than surrounding skin
- Fine, powdery scale that becomes visible when the skin is stretched or scraped (evoked scale sign)
- Mild itching or no symptoms
- Patches that become more obvious after sun exposure because they do not tan
Diagnosis
- Clinical
- Clinical: scaly, coloured patches on the trunk of a young adult; scraping shows fine scale. Under Wood's lamp the patches may show yellow-green fluorescence.
- Tests
- KOH preparation of scale shows short hyphae and round yeasts (the 'spaghetti and meatballs' appearance). Culture is not needed.
- Imaging
- Not needed.
Differential diagnosis
- Vitiligo (complete pigment loss, no scale)
- Pityriasis alba (on the face of children with atopy)
- Pityriasis rosea (herald patch, Christmas-tree pattern)
- Seborrhoeic dermatitis
- Tinea corporis
- Hansen disease (leprosy) in hypopigmented, numb patches
Goal of treatment
Clear the yeast overgrowth and reduce recurrences; the colour usually takes months to return to normal after the infection is cured.
Treatment
- Medical
- Topical first: selenium sulfide or ketoconazole shampoo applied to the skin as a lotion, or topical azole or terbinafine creams for limited areas.
- Medical
- Oral azoles (fluconazole or itraconazole) for extensive, resistant or frequently recurring disease; oral terbinafine and griseofulvin are not effective.
- Conservative
- Explain that the pigment change persists after cure and is not a sign of treatment failure; avoid oily skin products.
- Medical
- Prophylaxis in recurrent cases: periodic topical antifungal washes before the hot season.
Drugs for this condition
Complications
- Long-lasting pigment change after cure
- Frequent recurrence, especially in hot climates
- Malassezia folliculitis (related condition with itchy papules on the back)
Prognosis
Benign. Treatment clears the infection, but recurrence is very common, and normal skin colour may take months to return.
Prevention
- Periodic antifungal washes in people with frequent relapses
- Light, breathable clothing and limiting sweating
- Avoiding oily skin products
Test yourself
Think of the answer, then tap the question to see it.
What organism causes pityriasis versicolor?
Malassezia yeasts, which are part of normal skin flora.
What is the classic KOH appearance?
Short hyphae and round yeasts, described as 'spaghetti and meatballs'.
Why are the patches often hypopigmented?
Malassezia produces azelaic acid, which inhibits tyrosinase in melanocytes.
Which oral antifungal is not effective for this infection?
Oral terbinafine (and griseofulvin); topical agents or oral azoles are used.
Related conditions
- Vitiligo
- Pityriasis rosea
- Dermatophytosis (tinea) and onychomycosis
- Seborrheic dermatitis
- Cutaneous and mucocutaneous candidiasis
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Tinea versicolor (MedlinePlus, US National Library of Medicine, 2026).
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