Tinea Versicolor

Causes, Symptoms & Treatment

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 in the stratum corneum and hair follicles of normal, healthy skin, but it causes problems when it starts overgrowing. The yeasts convert into a pathogenic form known as Malassezia furfur. There are a few things responsible for the 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 more active. It is also more common in tropical and semi-tropical climates. Tinea versicolor has a recurrence rate of 80 percent after 2 years.

Symptoms & Appearance

The rash of tinea versicolor is a hypopigmented, hyperpigmented or red flat eruption that may coalesce into large patches with an adherent fine scale. The rash occurs primarily on the trunk, but it can also occur on the extremities.

Hypopigmentation occurs because the yeast produces a chemical that turns off the melanocytes, resulting in decreased melanin production. Hyperpigmentation or redness occur as a result of the inflammatory response in the skin.

Symptoms of tinea versicolor include:

  • Patches of skin discoloration that appear lighter or darker than normal
  • Skin discoloration on the trunk, shoulders, chest and arms
  • Mild itching
  • Scales

The following rashes are sometimes confused with tinea versicolor:

Tinea Versicolor Diagnosis & Treatment

Doctors are able to diagnose tinea versicolor based on appearance. Additional testing usually isn't necessary, but it isn't entirely uncommon. There are three tests used to diagnose tinea versicolor: a KOH test, Wood's light examination and a fungal culture:

  • KOH test shows tinea versicolor's characteristic "spaghetti and meatballs" appearance under the microscope.
  • Wood's light examination shows the yeast glowing pale yellow.
  • Fungal cultures are made by adding oil to the culture medium, though these are rarely used.

There are a number of medications used to treat tinea versicolor. Because the yeasts responsible for this condition reside in the top layer of the skin, topical over the counter antifungal medications are typically very effective.

They include:

  • 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 medication, prescription medication may be necessary. Prescription oral medication, topical creams and shampoos are all used to treat tinea versicolor.

It is important to know that even though treatment eradicates the pathogenic yeasts, skin discoloration can persist for weeks until melanocytes start to produce melanin again. Tinea versicolor has a recurrence rate of 80 percent after 2 years, so periodic medication may be needed to prevent it.

Sources:

Mayo Clinic Staff. Tinea versicolor. 22 April 2015. Retrieved April 01, 2016

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