Tinea Versicolor Ringworm
Tinea versicolor ringworm is a fungal infection of the skin in humans and domestic animals such as sheep and cattle. Fungi are organisms that live by eating plant or animal material. Those that cause parasitic infection feed on keratin, the material found in the outer layer of skin, hair, and nails. These fungi flourish best on moist, warm skin. This condition has been prevalent since before 1906. Ringworm was treated with compounds of mercury at that time. Hairy areas of skin were often considered too difficult to treat, so the scalp was treated with x-rays. That procedure was then followed up with antiparasitic medication.
Recent estimates show up to twenty percent of the population is infected by ringworm or one of the other dermatophytoses. It is very common among people who play sports, particularly wrestling. Misdiagnosis and treatment of ringworm with a topical steroid can result in tinea incognito, a circumstance where ringworm fungus will grow without the usual typical features like a distinctive raised border.
Tinea versicolor ringworm is often confused with other common rashes. It is also known as pityriasis versicolor. The following rashes can be easily confused with tinea versicolor are Vitiligo, Pityriasis alba, Seborrheic Dermatitis, Syphilis, Pityriasis Rosea, Nummular eczema, and Guttate psoriasis.
Tinea versicolor can occur at any age, but is most prevalent in adolescence and early adulthood. This is a time when the sebaceous glands are more active. It is also more common in tropical and semi-tropical climates. Tinea versicolor has a recurrence rate of 80% after two years.
Pityrosporum orbiculare and Pityrosporum ovale, are the yeasts that are a part of the common skin flora. They dwell in the stratum corneum and hair follicles and have an attraction for oil glands. Certain factors can trigger these yeasts to convert to a pathogenic form known as Malassezia furfur, which produces the rash of tinea versicolor. Predisposing factors include:
• Cushing’s disease
• Removal of the adrenal gland
• Pregnancy
• Malnutrition
• Burns
• Steroid therapy
• Suppressed immune system
• Oral contraceptives
• Excess heat
• Excess humidity
Three different tests for tinea versicolor are used in diagnosis of the infection. They are:
• A KOH test shows a characteristic “spaghetti and meatballs” appearance under the microscope.
• Under a Wood’s light examination, the yeast appears pale yellow.
• A fungal culture can be performed after adding oil to the culture medium, but it is rarely necessary.
