What Is Tinea Versicolor?

Superficial Fungal Rash With High Rates of Reoccurence

Dermatologist examining patient
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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 that typically appear on the trunk and shoulders.

What Causes Tinea Versicolor?

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 an outbreak of characteristic rash.

There are a number of things that lead to yeast overgrowth, including:

  • removal of the adrenal gland
  • cushing's disease
  • pregnancy
  • hormonal changes
  • malnutrition
  • burns
  • 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 more common in tropical and semi-tropical climates.

Of people previously infected, tinea versicolor has a recurrence rate of around 80 percent after two years.

Symptoms and Appearance of Tinea Versicolor

The rash of tinea versicolor can be hypopigmented, hyperpigmented, or present with a red, flat eruption that can coalesce into larger patches with a fine scale.

The rash occurs primarily on the trunk but can also appear on the arms or legs.

Hypopigmentation occurs when the yeast produces a specific chemical that turns off melanocytes, resulting in the decreased production of melanin (the pigment central to skin, eye, and hair color). Hyperpigmentation is the result of an inflammatory skin response to the fungus itself.

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
  • scaling

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 clinical appearance of the rash. Additional testing is usually unnecessary, although it isn't entirely uncommon in more severe cases.

There are three tests commonly used to confirm tinea versicolor. Among them:

  • KOH test can confirm the rash's characteristic "spaghetti and meatballs" appearance beenath the microscope.
  • The Wood's light examination will make the yeast glow a pale yellow beneath black light.
  • Fungal cultures, while infrequently used, can confirm infection by growing the fungus on a culture medium.

Treatment of Tinea Versicolor

There are a number of medications used to treat tinea versicolor. Topical, over the-counter antifungal creams are typically effective in eradicate 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 option doctors will consider.

Finally, it is important to remember that even though treatment eradicates the pathogenic yeasts, skin discoloration can persist for weeks until melanocytes start to produce melanin again. Even after resolution, occasional re-treatment may be need given the high rate of disease reoccurence.

Sources:

American Academy of Dermatology. "Tinea Versicolor: Overview." Washington, D.C.; 2017.

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