Diseases

Pityriasis versicolor

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Pityriasis versicolor (Bile fungus) is a fungal disease of the superficial layers of the skin. It is characterized by blotchy skin changes especially on the back and chest. A yeast that belongs to the natural skin flora is the trigger of pityriasis versicolor. Therapy and disease progression depend on the extent of the infection and individual health factors. Read all important information about Pityriasis versicolor!

ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in medical reports or on incapacity certificates. B36Article overviewPityriasis versicolor

  • description
  • symptoms
  • Causes and risk factors
  • Examinations and diagnosis
  • treatment
  • Disease course and prognosis

Pityriasis versicolor: description

Pityriasis versicolor (also called bran mushroom) is a harmless fungal disease of the skin that affects only the upper layers of the skin. The triggers of pityriasis versicolor are certain yeast fungi of the genus Malassezia. They belong to the natural skin flora and settle in healthy people in the hair follicles and adjacent skin areas, especially on the head.

An outbreak of pityriasis versicolor occurs when the yeast fungus suddenly proliferate uninhibited. They also colonize body parts outside of the hair follicles. What exactly sets the strong increase, is not yet clear. However, some risk factors are known that may favor the outbreak of a bran fungus. This includes, for example, heavy sweating.

Unlike other fungal diseases, pityriasis versicolor is not contagious - even in direct contact with patients.

Pityriasis versicolor is the world's most common superficial fungal infection. Above all, adolescents from puberty and adults are affected. In Germany, pityriasis versicolor is found in one to four percent of the population, in tropical regions by 30 to 40 percent. The risk of relapse is very high, especially in people with certain risk factors for fungal infections.

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Pityriasis versicolor: symptoms

Strong proliferation of Malassezia mushrooms in pityriasis versicolor produces dense mushroom carpets on the skin: they first appear as lentil to penny-sized, round, sharply defined patches, the color of which differs significantly from the normal skin color. These spots may fuse together to form irregularly shaped, large-scale discolorations. The color of the discoloration ranges from whitish to reddish-brown. Basically, there are light spots on dark skin and dark spots on light skin. This color variance is clarified by the term "versicolor" (multicolored) and comes about as follows:

The mushroom carpet does not allow sun rays (UV rays) to penetrate the underlying skin, which prevents the formation of the skin pigment melanin. In addition, the fungus produces toxins that inhibit melanin synthesis in the skin. This results in light spots (hypopigmentation) on dark or tanned skin. This form of bran fungus is called "Pityriasis versicolor alba".

On light skin, on the other hand, the fungus can lead to reddish-brownish skin lesions due to the formation of its own pigments (hyperpigmentation). Then one speaks of "Pityriasis versicolor rubra".

From the affected areas, fine, skin-shaped scales can peel off. It refers to the German name of the disease "bran fungus".

The skin spots of the bran fungus occur mainly on sebaceous skin areas on the trunk, so mostly on the chest and on the back. Other parts such as shoulders, arms and neck may also be affected. Sometimes a slight itching occurs.

In rare cases, skin involvement with Malassezia fungi causes inflammation of hair follicles (malassezia folliculitis). Affected are preferably people with immunodeficiency (either by medication or HIV infection).

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Pityriasis versicolor: causes and risk factors

The cause of pityriasis versicolor are certain yeasts, especially Malassezia globosa and Malassezia sympoldialis, more rarely Malassezia furfur. These fungi are present in all healthy people to some extent and form together with other microorganisms the normal skin flora. For unknown reasons, they may suddenly begin to proliferate excessively, disrupting the balance of natural skin flora.

Meanwhile, one knows some risk factors that can favor the appearance of pityriasis versicolor. This includes a moist, warm environment in which the mushrooms can multiply well. Therefore, Pityriasis versicolor is so prevalent in tropical countries. Heavy sweating (hyperhidrosis) and increased sebum production (seborrhea) also promote fungal growth. Other risk factors of pityriasis versicolor include, for example, the frequent use of fatty creams and a weakened immune system - such as medications or underlying diseases such as HIV.

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Pityriasis versicolor: examinations and diagnosis

The right contact for every type of skin change is the dermatologist. In a first conversation this raises the medical history (medical history). You have the opportunity to describe your complaints exactly. This can help the doctor to make a suspected diagnosis. In order to rule out certain causes of the existing symptoms and to be able to further narrow down the type of illness, the doctor also asks questions during the anamnesis interview, such as:

  • Have you been on vacation recently, and if so, where?
  • Are your family's skin diseases known?
  • Have you ever had such skin changes?

The medical history is followed by a physical examination. The doctor examines the lesions and strokes with a spatula over it. At the same time, the smallish scales that are typical for pityriasis versicolor can detach.

In order to determine the causative agent of the skin lesions, the microscope continues to help: The doctor scrape a sample of the affected skin for review or he sticks a piece of Tesafilm on the skin patches, presses it firmly, then tears it off, stains it and lays under the microscope: Pityriasis versicolor contains clustered roundish spores of Malassezia mushrooms and short fungal threads. The whole thing is reminiscent of "spaghetti and meatballs".

In addition, the doctor can examine the skin lesions with special light, the so-called Wood light. Skin spots on which there are fungi fluoresce yellowish-green.

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