Tinea pedis, tinea pedum, foot mycosis, athlete’s foot, dermatophyte infection of the foot
Definition
A foot fungus, tinea pedis, is a usually protracted infection of the interdigital spaces between the toes, the soles of the feet and, in severe cases, the back of the foot with a filamentous fungus (dermatophyte). Dermatophytes attack especially the skin and its appendages such as hair and nails. If one or more nails on the toes are also affected, one speaks additionally of a nail fungus. About every third person in the industrialized countries is affected by a foot fungus infection, whereby men suffer from the disease more often than women. What are the signs of athlete’s foot?
Different types
The foot fungus pathogens are too small to be seen with the naked eye. However, there are typical signs that can confirm the diagnosis of athlete’s foot. As soon as the filamentous fungi penetrate the uppermost skin layer (the stratum corneum), they spread there and break down the keratin (the horny substance) of the skin.
A local inflammatory reaction develops. There are different forms of athlete’s foot, each of which has different symptoms.
- Dyshidrotic type: On the arch of the foot and on the edges of the foot there are small blisters filled with a turbid liquid.
The bubbles have a thread-pulling content. They do not burst open, but heal under a scaly crust. The typical signs of this type of athlete’s foot are severe itching and a feeling of tension at the edge and arch of the foot.
If the disease is prolonged, it is possible that old and new blisters as well as dandruff coexist. This results in a colorful picture of skin changes. As soon as large blisters develop, one speaks of the bullous type.
Dyshidrosis comes from the Greek and means bad/bad sweat. Contrary to earlier assumptions, it has been shown that there is no connection between the blistering skin changes and the function of the sweat glands.
- Interdigital type: Interdigital means translated between the toes. Especially the space between the toes of the 3rd and 4th or the 4th and 5th toe are affected due to the especially narrow distance.
This form is the most common type of athlete’s foot infection. In the beginning, the uppermost skin layer is soaked. If one spreads the toes, one can recognize a gray-white, swollen skin of the toe interspace.
As soon as the soaked skin detaches, weeping superficial injuries and deeper cracks can be seen. The bottom of the swollen skin is reddened and eventually scaling of the skin occurs. This can lead to an additional infection of the affected areas with bacteria, resulting in an unpleasant foot odor.
The interdigital type can exist for a very long time without being noticed and thus spread further. If there is increased sweating of the feet, a strong itching in the interdigital space between the toes develops. The great danger of the interdigital type of athlete’s foot is the erysipelas.
The small injuries represent a good entry portal for the bacteria.
- Squamous-hyperkeratotic type: The frequently occurring form is initially accompanied by very fine dry scaling on only slightly reddened, inflamed ground. If the condition persists over a longer period of time, focal, clearly defined, scaly, excessively keratinized areas of the skin (hyperkeratosis) may occur. They are often accompanied by small skin cracks (rhagades).
This form occurs mainly on the edges of the feet, tips of the toes and heels.
- Moccasin type: This is a mostly dry, scattered scaling, which rests on whitish or only slightly reddened plaques. It occurs mainly on the entire sole of the foot in the form of a moccasin. Another important sign of this form of athlete’s foot is the involvement of the nails.
- Oligosymptomatic type: In this form of athlete’s foot, several signs occur simultaneously. There is a slight reddening of the spaces between the toes and excessive hornification of the skin with accompanying fine scaling. It mainly affects the heels and edges of the foot.
