Sun, surf and spots

A 21-year-old man presents with an asymptomatic pale ‘spotty’ rash on his trunk that has spread over summer.

He is concerned about the unsightly appearance, especially when he is bare-chested at the surf club. He is also concerned that it may be infectious. What is your diagnosis and management?

Figures A and B: Pityriasis versicolor presents as finely scaling discoloured patches on the trunk.

DIAGNOSIS

Pityriasis versicolor (PV), or tinea versicolor, is a common condition affecting adolescents and young adults. PV presents as finely scaling discoloured spots/patches on the trunk that are occasionally itchy (see Figures A and B). White-skinned individuals tend to have tanned spots, whereas darker-skinned people tend to have pale spots.

PV is caused by the Pityrosporum/Malassezia yeasts normally found in the pores of human skin.

Despite its alternative name (tinea versicolor), it is not a fungal/dermatophyte infection. As the yeast is a commensal organism found in all individuals, the condition is non-infective.

The commensal yeasts cause PV when they become overactive and overabundant. Increased sweating and sebaceous activity in hot, humid environments predispose towards PV through yeast proliferation.

The morphology of the rash and the typical T-shirt distribution allow for an accurate clinical diagnosis. PV can be confirmed by skin scraping with KOH and microscopy revealing diagnostic yeasts and hyphae.

In atypical cases, differential diagnoses may include pityriasis alba (eczema with white patches), seborrheic dermatitis, pityriasis rosea and secondary syphilis.

TREATMENT OPTIONS

Topical anti-yeast agents:

• Selenium sulfide (Selsun shampoo)
• Azoles – clotrimazole (Canesten), miconazole (Daktarin), econazole (Pevaryl), ketoconazole (Nizoral) etc
• Non-azoles – terbinafine (Lamisil)

Oral anti-yeast agents:

• Ketoconazole (Nizoral), fluconazole (Diflucan), itraconazole (Sporanox).

Treatment is aimed at controlling the numbers and activity of the Pityrosporum yeast. As it is not possible to eradicate the commensal yeast, recurrences can recur, especially in summer.

Topical anti-yeast agents are first-line therapy. Severe or resistant cases may respond to short courses of systemic antifungals. In recurrent cases, maintenance therapy is recommended.

MANAGEMENT

Reassure that the condition is not infectious, can be effectively treated but may recur. Explain that the pale spots may take months to recover despite effective treatment. Provide written instructions for the patient to follow.

This patient was instructed to lather Nizoral 2% shampoo over his torso (T-shirt area) and leave it for 10 minutes before rinsing off. This was repeated over three days, then once a week for a month.

As the patient was anxious to minimise recurrences, he was advised to continue the above treatment on the first day of each month as maintenance therapy.

KEY FACTS: Pityrosporum versicolor

• Caused by commensal Pityrosporum/Malassezia yeast
• More common in adolescents/young adults
• All races, M = F
• Typically T-shirt distribution (sebaceous rich areas)
• Not infectious
• Tends to occur in hot humid climate
• Fine scaly pale to tanned macules and patches
• Asymptomatic to mild itching
• Skin scraping microscopy: ‘spaghetti and meatball’ pattern
• Discolouration (without scales) may persist despite successful treatment
• Anti-yeast treatments effective but PV may recur.

Written by Dr Adrian Lim, fellow of the Australasian College of Dermatologists.

Coordinated by Dr Stephen Shumack, honorary secretary, Australasian College of Dermatologists.