Tinea Versicolor

Tinea versicolor, also known as pityriasis versicolor, is a common skin condition characterised by a fungal infection that leads to a distinctive skin eruption on the trunk and proximal extremities. The condition is primarily caused by the fungus Malassezia globosa, with Malassezia furfur accounting for a smaller number of cases.

These yeasts are naturally present on human skin but become pathogenic under certain conditions, such as warm and humid environments. However, the exact triggers for the disease process are not fully understood.

Pityriasis versicolor commonly causes hypopigmentation in people with dark skin tones.

Signs and Symptoms

Tinea versicolor manifests with several distinctive signs and symptoms. Patients may notice occasional fine scaling of the skin, producing a superficial ash-like scale. The affected areas can be pale, dark tan, or pink with a reddish undertone that may darken when the patient is overheated, such as after a hot shower or exercise.

Tanning typically accentuates the contrast between the affected and normal skin, making the condition more noticeable. The lesions usually have a sharp border. In individuals with dark skin tones, hypopigmentation or loss of colour is common, while hyperpigmentation tends to occur in those with lighter skin. The term "sun fungus" is sometimes used to describe the condition due to its association with uneven tanning.

Pityriasis versicolor in a man and electron micrograph of his skin showing round Malassezia spores (S)

The condition is more prevalent in hot, humid climates and among individuals who sweat heavily, often recurring each summer. Under a microscope, the yeasts within the lesions exhibit a "spaghetti and meatball" appearance due to the round yeasts producing filaments.

Pathophysiology

In cases where Malassezia furfur is the causative agent, the fungus produces azelaic acid, which has a slight bleaching effect on the skin, leading to lightening of the affected areas.

Diagnosis

Tinea versicolor fluorescence under Wood's lamp

Tinea versicolor can be diagnosed using a potassium hydroxide (KOH) preparation, where the lesions may fluoresce copper-orange under a Wood's lamp (UV-A light). Differential diagnoses for tinea versicolor include progressive macular hypomelanosis, pityriasis alba, pityriasis rosea, seborrheic dermatitis, erythrasma, vitiligo, leprosy, syphilis, and post-inflammatory hypopigmentation.

Treatment

Treatment options for tinea versicolor include topical and oral antifungal medications. Topical treatments often recommended are selenium sulphide and ketoconazole (Nizoral ointment and shampoo). These are typically applied to dry skin and washed off after 20 minutes, repeated daily for two weeks. Ciclopirox (ciclopirox olamine) is an alternative to ketoconazole, as it suppresses the growth of Malassezia furfur and provides additional anti-inflammatory benefits.

Other topical agents like clotrimazole, miconazole, terbinafine, or zinc pyrithione may also alleviate symptoms. Hydrogen peroxide has been used in some cases but may cause permanent scarring.

Oral medications are considered second-line treatments for widespread, severe, or recurrent cases. Itraconazole (200 mg daily for seven days) and fluconazole (150 to 300 mg weekly for 2 to 4 weeks) are preferred over oral ketoconazole due to the latter's potential hepatotoxicity.

To enhance the effectiveness of these treatments, patients are advised to exercise 1–2 hours after taking the medication to induce sweating, allowing the medication to remain on the skin by delaying showering for a day.

Epidemiology

Tinea versicolor commonly affects adolescents and young adults, particularly in warm and humid climates. The yeast thrives on skin oils (lipids) and dead skin cells. Infections are more frequent in individuals with seborrheic dermatitis, dandruff, and hyperhidrosis.

Self-assessment MCQs (single best answer)

What is the primary cause of tinea versicolor?

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Which of the following is a common symptom of tinea versicolor?

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Which of these environmental conditions is most likely to trigger tinea versicolor?

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What does the "spaghetti and meatball" appearance in microscopy indicate?

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Which topical antifungal treatment is commonly recommended for tinea versicolor?

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Which of the following is a second-line treatment for severe tinea versicolor?

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Under a Wood's lamp, what colour do tinea versicolor lesions typically fluoresce?

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Which of these conditions is NOT a differential diagnosis for tinea versicolor?

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What is the preferred treatment regimen for fluconazole in tinea versicolor cases?

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Which population is most commonly affected by tinea versicolor?

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