Tinea versicolor – Symptoms and causes
Tinea versicolor, also known as pityriasis versicolor, is a superficial fungal infection of the skin that is often confused with other common rashes. The fungus affects the skin’s pigmentation and results in small, light- or dark-colored patches which typically appear on the trunk and shoulders.
Tinea versicolor is a fungal infection caused by the yeasts Pityrosporum orbiculare and Pityrosporum ovale. These yeasts are found on the outer layer of skin(stratum corneum) and hair follicles of normal, healthy skin.Though generally harmless, these yeasts can sometimes experience overgrowth and convert into a pathogenic form known as Malassezia furfur, resulting in the outbreak of the rash.There are a number of things that lead to yeast overgrowth, including:
- removal of the adrenal gland
- Cushing’s disease
- hormonal changes
- steroid therapy
- suppressed immune system
- oral contraceptives
- hot, humid weather
- oily skin
Tinea versicolor can occur at any age but is most common in adolescence and early adulthood (a time when the sebaceous glands are at their more active). It is also commonly seen in tropical and semi-tropical climates.Of people previously infected, tinea versicolor has a recurrence rate of around 80 percent after two years.
The rash of tinea versicolor can be hypopigmented or hyperpigmented, and appear as a red, flat eruption that can gradually converge into larger patches. The rash often has a fine scaly texture, developing mainly on the trunk but also on the arms and legs.Hypopigmentation occurs when the yeast produces a specific chemical that turns off melanocytes, resulting in a decreased production of melanin (the pigment central to the skin, eye, and hair color). Hyperpigmentation is the result of inflammation caused by the fungal infection.Symptoms of tinea versicolor include:
- patches of skin discoloration that appear lighter or darker than normal
- skin discoloration on the trunk, shoulders, chest, or arms
- mild itching
There are a number of rashes that are frequently confused with tinea versicolor, including vitiligo, syphilis, pityriasis rosea, pityriasis alba, eczema, psoriasis, and seborrheic dermatitis.
Diagnosis of Tinea Versicolor
Doctors diagnose tinea versicolor based on the appearance of the rash. Additional testing is usually unnecessary, although it may be used in more severe cases.Outside of a physical examination, there are three tests that doctors use to confirm tinea versicolor:
- A KOH test can confirm the rash’s characteristic “spaghetti and meatballs” appearance beneath the microscope.
- The Wood’s light examination will make the yeast glow a pale yellow beneath a black light.
- Fungal cultures, while infrequently used, can confirm infection by growing the fungus on a culture medium.
Treatment of Tinea Versicolor
There are several medications commonly used to treat tinea versicolor. Of these, topical, over-the-counter antifungal creams are usually effective in eradicating the fungus. They include such popular products as:
- Lotrimin AF
- Selsun Blue
- zinc pyrithione soap
If you have a particularly severe case of tinea versicolor, or if your body doesn’t respond to over-the-counter treatment, prescription medications may be required. Oral antifungals, as well as prescription antifungal creams and shampoos, are just some of the options doctors will consider.
Finally, it is important to remember that even though treatment kills the pathogenic yeasts, skin discoloration can persist for weeks until melanocytes are able to produce melanin again. Even after the infection has healed, occasional re-treatment may be needed given the high rate of disease recurrence.