Tinea cruris is a fungal disease of the lower leg. It usually develops from a spread of athlete's foot. Women are more frequently affected because they spread the fungal pathogens when shaving their legs. Severe itching and brown-reddish, scaly nodules are the result and the first signs of this disease.
Here you will find further information and selected tinea cruris specialists.
The term tinea cruris refers to an infection with a skin fungus on the lower leg. "Tinea" is the medical term for infections with dermatophytes. Dermatophytes are filamentous fungi and common pathogens of fungal skin diseases. In anatomy, "crus" is the name of the lower leg, the calf.
Other forms of tinea include
In the English-speaking world, tinea cruris is mistakenly equated with tinea inguinalis. However, the latter refers to the inguinal fungus. Skin fungi can easily settle there due to the moist, warm environment. However, this is not about tinea inguinalis.
Dermatophytes are filamentous fungi that have specialized on the skin of humans and animals.
Fungi live everywhere in nature. Fungi can settle in the soil, on plants, animals and humans. Depending on the species, they benefit from the prevailing environment. Around a quarter of the earth's total biomass is made up of fungi! Many species of fungi live in symbiosis with trees and shrubs and enable their plant growth.
From a human medical point of view, in addition to dermatophytes, there are also
Skin fungi feed on human keratin, an essential component of the cornea. They therefore only infest
We usually catch them through direct infection or transmission via inanimate objects:
These are all common routes of infection for dermatophytes. Transmission from animal fur to humans is also possible. This is particularly common in children (e.g. tinea capitis).
For a mycosis, i.e. a fungal infection, to develop, the pathogen must first penetrate the skin. There it must evade the host's immune defense.
Most fungi are facultative pathogens. This means that they can only trigger a disease if the skin barrier is impaired or the human immune system is deficient. This is referred to as an "opportunistic infection".
Favoring factors for such an opportunist can be, for example, circulatory disorders of the skin. These include, for example, pre-existing conditions such as
Diabetes mellitus, the very common form of diabetes today, also weakens the immune system.
Many other underlying diseases and modern medications weaken the immune system.
However, you don't have to be seriously ill to catch a fungus: Young children often still have an immature immune system and get a skin fungus relatively easily.
Tinea cruris is not usually a primary infection. As a rule, the affected person has been suffering from athlete's foot for some time. If this spreads upwards, tinea cruris develops.
Athlete's foot is the most common dermatophyte infection. It usually affects the sweaty spaces between the toes, where microorganisms find their preferred living conditions.
The athlete's foot infection can go unnoticed for a long time. People are not even aware that there is a risk of it spreading. The fungus can be "smeared" by hand and thus reach the ankle region and lower leg.
The entry point for tinea cruris is often the razor: when shaving the legs, it is unavoidable that minimal injuries to the skin occur. The dermatophytes that are inevitably picked up by the blade get directly into the skin and settle mainly in the ruptured hair follicles.
When shaving the legs, small wounds inevitably occur through which pathogens can penetrate the skin © Mykola | AdobeStock
In general, fungal infections are usually characterized by
noticeable.
Sometimes the skin oozes or cracks. The reason for this is that the fungi trigger an inflammation in the uppermost layers of the skin (tinea superficialis). This infection can also go deeper and cause pustules and inflammatory infiltrates (tinea profunda). However, this only happens with a severely weakened immune system or particularly aggressive fungi (especially those dermatophytes of the animal world).
In the case of tinea cruris, the inflammation can often be easily assigned to the hair follicles. They show brown or blue-reddish, pea-sized nodules and usually have a scaly edge. Severe itching in the corresponding areas is obligatory. The outer sides of the lower legs are particularly affected.
If you notice these symptoms, you should consult a dermatologist (or your family doctor first). They can clarify the problem.
For the doctor, tinea cruris is often a visual diagnosis. It results from
In case of doubt, the diagnosis must be confirmed microscopically.
However, this does not provide any information about the exact pathogen that caused the mycosis. A fungal culture is necessary for this. It develops from the tissue sample in a petri dish over several weeks. This allows conclusions to be drawn about the exact fungal species and possible resistance to antimycotics. Fast-growing dermatophytes can be identified after one week at the earliest.
The examination material for the diagnosis of tinea cruris are
taken from the edges of the affected areas. In the case of the lower leg, a thick swab is usually sufficient.
Another method of diagnosing fungi is the Wood lamp. A Wood lamp emits UV light. This allows some types of dermatophytes to be recognized as fluorescent areas on the skin in a darkened room. However, this method is only of secondary importance, as fungal microscopy and culture are usually carried out anyway.
The treatment of fungal infections of the skin such as tinea cruris is generally carried out in two graduated "lines of attack":
The first line is topical therapy, which should always be used if possible. "Topical" means that the antifungal agent is applied "on the spot". It is therefore a local therapy. Solutions, creams or ointments are available for this purpose.
The active ingredients used here are mainly
In the case of very superficial tinea cruris, application over a few days to four weeks may be sufficient.
Side effects rarely occur as the active ingredient does not enter the bloodstream in significant quantities. This prevents it from spreading throughout the body.
The disadvantage of topical therapy is the often quite long duration of treatment.
Individual fungal cells can remain as spores in the horny layers of the epidermis for a long time. Spores are very robust and can hardly be attacked. Although antifungal agents prevent the pathogens from growing and multiplying, they do not kill them. Therefore, the aim of treatment is to continue until all current skin cells, including the spores they contain, have been shed.
If itching and redness subside after a few days, the inflammation has already been successfully combated. However, up to four weeks of topical therapy are sometimes necessary to completely clear the skin.
A second problem with topical therapy is that it often only has a very superficial effect. Deeper fungi withdraw, as the skin's defense barrier is also directed against the medication.
In addition, new infections (reinfections) can easily occur.
Persistent or extensive skin fungi such as tinea cruris are therefore often treated "systemically" from the outset. Systemic means that the active ingredients are not applied locally, but act throughout the entire organism.
This is done in the form of tablets. As the entire body is affected, side effects can occur.
Systemic antimycotics damage the liver. Good liver function is therefore a prerequisite for most antimycotic agents.
The following are used
Systemic application leads to better accumulation in the cornea and better healing rates. The application time can usually be reduced by about half. Two weeks is usual in most cases. A combination with local therapy is also possible.
Tinea cruris is a serious and persistent disease. It requires decisive action. The fungi do not pose any immediate danger, as they only feel comfortable on the skin. However, the infestation is a major cosmetic problem and leads to skin inflammation and unbearable itching.
The risks of treatment over two weeks, on the other hand, are quite manageable. The liver values may need to be determined. However, tinea cruris is usually very easy to treat.
