Definition
Bran lichen is also known under the name “Pityriasis versicolor“. It is a fungal disease of the upper layer of skin, which can also be accompanied by signs of inflammation. It is typically located on the neck or upper trunk (chest and back).
The pathogen causing the pityriasis is Malassezia furfur, a yeast fungus of the normal skin flora. The infection leads to small spots of pigmentation. On tanned skin, the flocks appear bright, as the fungus can absorb UV light. In winter, the fungal foci appear brownish again next to the pale skin.
How contagious is the pityriasis?
Since Malassezia furfur is a yeast fungus of the normal skin flora anyway, the pityriasis is not an infectious disease. Everyone carries this yeast fungus on his own skin. The symptoms occur only if certain risk factors apply.
Causes
The skin symptoms caused by the yeast fungus Malassezia furfur of the skin flora only appear when certain risk factors favour the growth of the yeast fungus. Among the risk factors are heavy sweating and overproduction of the sebaceous glands. In addition, a hot and humid climate.
Under these warm and humid conditions the yeast fungus feels comfortable and can spread well. Overweight is also one of the risk factors, since a suitable climate is also formed in large skin folds. Stress can also be responsible for the disease, as the immune system is weakened under stress.
Associated symptoms
In the case of bran lichen, other symptoms can also occur in addition to the brown to reddish or under the influence of sunlight brightly appearing foci. A slight itching, for example, is possible but does not have to occur. In patients with a weakened immune system (e.g. those with HIV or under chemotherapy), it is also possible that an inflammatory infection of the hair follicle exits beyond the pure “spots”.
Diagnosis
The diagnosis of pityriasis versicolor can usually be made by the typical color change of the fungal foci compared to tanned or untanned skin. Dermatologists also stroke the flock with a spatula, which causes a fine whitish scaling. This so-called “wood shaving phenomenon” is typical for the disease. In addition, the pathogen can be detected under the microscope by means of an adhesive strip swab and a methylene blue stain.