|Classification and external resources|
Tinea versicolor (also known as dermatomycosis furfuracea, pityriasis versicolor, and tinea flava) is a condition characterized by a skin eruption on the trunk and proximal extremities. Recent research has shown that the majority of tinea versicolor is caused by the Malassezia globosa fungus, although Malassezia furfur is responsible for a small number of cases. These yeasts are normally found on the human skin and only become troublesome under certain circumstances, such as a warm and humid environment, although the exact conditions that cause initiation of the disease process are poorly understood.
The symptoms of this condition include:
- Occasional fine scaling of the skin producing a very superficial ash-like scale
- Pale, dark tan, or pink in color, with a reddish undertone that can darken when the patient is overheated, such as in a hot shower or during/after exercise, tanning typically makes the affected areas contrast more starkly with the surrounding skin.
- Sharp border 
Pityriasis versicolor is more common in hot, humid climates or in those who sweat heavily, so it may recur each summer.
The yeasts can often be seen under the microscope within the lesions and typically have a so-called "spaghetti and meatball appearance" as the round yeasts produce filaments.
In people with dark skin tones, pigmentary changes such as hypopigmentation (loss of color) are common, while in those with lighter skin color, hyperpigmentation (increase in skin color) is more common. These discolorations have led to the term "sun fungus".
This skin disease commonly affects adolescents and young adults, especially in warm and humid climates. The yeast is thought to feed on skin oils (lipids), as well as dead skin cells. Infections are more common in people who have seborrheic dermatitis, dandruff, and hyperhidrosis.
Tinea versicolor may be diagnosed by a potassium hydroxide (KOH) preparation and lesions may fluoresce copper-orange when exposed to Wood's lamp. The differential diagnosis for tinea versicolor infection includes:
- Pityriasis alba
- Pityriasis rosea
- Seborrheic dermatitis
- Post-inflammatory hypopigmentation
Treatments for tinea versicolor include:
- Topical antifungal medications containing 2.5% selenium sulfide are often recommended. Ketoconazole (Nizoral ointment and shampoo) is another treatment. It is normally applied to dry skin and washed off after 10 minutes, repeated daily for 2 weeks. Ciclopirox (Ciclopirox olamine) is an alternative treatment to ketoconazole, as it suppresses growth of the yeast Malassezia furfur. Initial results show similar efficacy to ketoconazole with a relative increase in subjective symptom relief due to its inherent anti-inflammatory properties. Other topical antifungal agents such as clotrimazole, miconazole, or terbinafine can lessen symptoms in some patients. Additionally, hydrogen peroxide has been known to lessen symptoms, and on certain occasions, remove the problem, although permanent scarring has occurred with this treatment in some sufferers. Clotrimazole (1%) is also used combined with selenium sulfide (2.5%) (Candid-TV).
- Oral antifungal prescription-only medications include 400 mg of ketoconazole or fluconazole in a single dose, or ketoconazole 200 mg daily for 7 days, or itraconazole 400 mg daily for 3–7 days. The single-dose regimens, or pulse therapy regimes, can be made more effective by having the patient exercise 1–2 hours after the dose, to induce sweating. The sweat is allowed to evaporate, and showering is delayed for a day, leaving a film of the medication on the skin.
- Recurrence is common and may be reduced by intermittent application of topical antifungal agents such as tea tree oil or selenium sulfide.
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