Clinical presentation of DM varies largely. It depends on the causative agent, on the affected area of the body and on the condition of the patient's immune system:

• Tinea pedis is the most common DM and is also called athlete’s foot. It usually manifests between the toes. Affected skin appears reddened, scaly and sometimes chapped. Blisters are uncommon. As is the case with the following forms of tinea, patients report pruritus.
• Tinea unguium is associated with brittle, thickened nails and discoloration. Toenails are more frequently affected than fingernails.
• Tinea cruris often develops between scrotum and thighs because continuous skin contact tends to create a warm, humid environment that favors fungal growth. This disease is, however, not limited to men. In mild to moderate cases, it manifests in form of red rash, often of round shape.
• Tinea manuum often develops in interdigital areas and is of similar appearance as tinea pedis.
• Tinea capitis is mostly detected in young pediatric patients. While it may present as red, itching rash, erythema may also be missing. The skin may be dry and scaly. Alopecia is common.
• Tinea corporis is also called ringworm because of the round or ring-shaped rash it may produce on any part of the body.
• Intertrigo is usually triggered by C. albicans. The warm, humid microclimate created between skin folds facilitates yeast growth. It may manifest as extensive, intensively red to brown rash or in form of solitary red patches. Yeast infections may also cause pruritus.
• Diaper candidiasis is very similar to intertrigo.
• Malassezia spp. may cause a variety of diseases, e.g., dandruff, seborrheic dermatitis and pityriasis versicolor. In general, they are also associated to scaly, red to brown skin and pruritus. Each disorder is further characterized by more specific symptoms.

Tinea pedis is not only the most common form of DM, it may also be the primary lesion that serves as a reservoir for pathogens that are subsequently transmitted to other areas of the body. Thus, it is not uncommon to see more than one type of tinea in the same patient. Any DM patient should be checked for tinea pedis and other forms of DM.

Typical findings in a dermatological examination may raise the suspicion of DM and this may be further supported by a medical history pointing out any form of immunodeficiency. However, skin alterations caused by DM are little specific. There are a plethora of dermatological diseases causing scaly, red patches and pruritus.

Confirmation of the suspected diagnosis requires direct proof of the presence of fungal pathogens. The alkaline solution potassium hydroxide is readily available and allows for a fast detection of fungi. While the exact species may not be determined, dermatophytes and yeasts may be distinguished. In order to carry out this test, skin, nail or hair samples need to be obtained, and then treated with potassium hydroxide for cell lysis to occur, heated slightly and examined under a microscope. For species determination, fungal cultures need to be established. The latter may be of great value if resistances to antimycotic drugs are encountered.

Of note, the aforementioned tests may also be conducted to assess response to therapy [15].

There are several antimycotic drugs available for topical and systemic use. The aim of DM therapy is to eliminate the pathogen and to give skin, nails, and hair a chance to heal.

For focal, uncomplicated DM, topical treatment is usually sufficient. Triazoles like fluconazole are often administered, but compounds pertaining to other drug classes are probably as efficient. Patients showing extensive DM or who are at risk for systemic complications should receive systemic antimycotic treatment. Fluconazole may be applicated orally as well as itraconazole, griseofulvin, and many other compounds. Due to possible adverse effects, topical treatment should be preferred whenever possible. Unfortunately, immunodeficient patients are at particularly high risk for side effects, but they also constitute the risk group for the systemic spread. Thus, benefits and possible detriments have to be evaluated for every single case. Therapies should generally be continued until two weeks after resolution of all symptoms. Otherwise, there is a high risk of recurrence.

In general, patients should be advised to preventive measures, i.e., adequate hand and foot hygiene, cautious sharing of equipment with third parties, wearing loose, breathable clothes, and taking care in public pools and showers.

While most fungal skin infections are restricted locally, some may spread to other tissues. Systemic complications mainly occur in immunodeficient patients and may even be life-threatening [14].

DM may be grouped according to their causative agents and the layers of the skin that may be affected. A simple classification may look as follows:

• DP are DM caused by dermatophytes. They are limited to the epidermis, often even to the corneal layer of the skin. Pathogens pertaining to this group are Epidermophyton spp., Microsporum spp. and Trichophyton spp.
• Yeasts. While C. albicans is the best-known representative of this group, other Candida spp., Malassezia spp. and Cryptococcus spp. may also cause DM. Of note, Cryptococcus spp. are opportunistic pathogens that may also be considered part of the following group. They rarely cause DM but account for severe infections of lungs, meninges, and brain, particularly in immunodeficient patients.
• Opportunistic pathogens like Aspergillus spp. and Mucor spp. Infections with these fungi often occur as a secondary infection of DP.

Furthermore, anthropophilic and zoophilic etiologic agents of DM may be distinguished. While the former preferentially infect human beings, the latter are often transmitted by animals. Anthropophilic pathogens are typically associated with mild, chronic infections. In contrast, zoophilic fungi may cause pronounced acute reactions but are usually unable to maintain an infection for prolonged periods of time. Some fungi may be contracted from soil and are thus termed geophilic organisms.

Fungal infection of the skin is greatly facilitated by previously existing skin lesions. Also, any immunodeficiency - the severe form of HIV infection as well as diabetes mellitus - increases the individual risk of DM.

DM are very common dermatological diseases and the lifetime risk to contract such a disease has been estimated to range around 20% [7], but such numbers vary widely between different studies. Incidence and prevalence rates are increased in warm, humid climates.

With regards to the above-mentioned classification system, dermatophytes have been reported to account for nearly 90% of all DM cases. Candida spp. and Malassezia spp. presumably trigger the remaining 10%. Significantly less than 1% of all cases are caused by opportunistic pathogens pertaining to the latter group.

DP were most often seen in feet, nails, groin, hands and head. A very high incidence has also been reported for tinea corporis, whereby this description is less specific than the aforementioned ones. Trichophyton spp. are most frequently isolated.

Yeast infections typically manifest as intertrigo, but may also be detected between fingers and in the diaper area.

There seems to be an overall positive correlation between DM prevalence and age and one study reported more than half of all participants aged 80 years and older to present onychomycosis [13]. However, specific forms of DM are more prevalent at younger ages. For instance, tinea capitis is most frequently diagnosed in children, tinea cruris in adolescents.

The human skin disposes of several defense mechanisms that may, however, be ineffective to prevent fungi from entering the tissue through abrasions, other traumatic lesions, irritation due to dermatological alterations and maceration. Skin maceration is a typical problem of those that use public pools and showers. Additionally, fungal loads in these establishments are often very high. Use of tight, non-breathable clothing may lead to fungal growth-promoting warmth and humidity.

Fungi enter the epidermis, germinate and produce proteases, phospholipases, and lipases. These enzymes are their major pathogenicity factors. DP require keratin for growth and development. They mainly release keratinases and may not spread to deeper skin layers. Some yeasts are able to produce more resistant biofilms.

There are several preventive measures that may be carried out:

• Maintenance of foot hygiene, washing hands after touching feet (or any other infected area of the body) and regular change of clothes.
• Preference of loose, breathable clothes over tight, non-breathable ones.
• Use of talcum to absorb sweat.
• Use of slippers in public pools and showers.
• Maintenance of a healthy body weight.
• Avoidance of contact with other infected persons or animals.
• Hygiene articles and clothes should not be shared with third persons.
• Any measure to avoid immune suppression.

The term dermatomycosis (DM) refers to any fungal infection of the skin. This group of diseases may be further subdivided and indeed, most DM are caused by dermatophytes and may thus be designated dermatophytoses (DP). Even though these terms are sometimes used interchangeably, pathogens other than dermatophytes may cause DM. In this context, yeasts like Candida spp., particularly Candida albicans (C. albicans), and Malassezia spp., are of clinical importance [1]. The third group of causative agents of DM comprises opportunistic pathogens that most frequently affect immunodeficient patients.

Fungal infections of the skin are very common, notably in the warm, moist climates of the tropics [2] [3] [4] [5] [6]. As has been indicated above, DP like tinea corporis account for the majority of cases. Of note, tinea is merely another designation for DP. This term is usually combined with a second noun indicating the location of the dermatological lesion. In this case, "corporis" may refer to any more or less hairless part of the body. Because standard dermatological treatments to remedy burning sensations and pruritus often contain corticosteroids that do, however, reduce local immunity and promote fungal growth, greater awareness for the high prevalence of DM is required [7].

While the clinical presentation of a DM patient may hint at a fungal infection of their skin, it is rather difficult to diagnose which species accounts for the respective case. To this end, microscopic examination of tissue samples and fungal cultures may be very helpful. Topical or systemic administration of antimycotic drugs is the treatment of choice. It will be adjusted to the precise location of DM, its severity and extension, as well as to the etiologic agent [8] [9]. In most cases, topical antifungals are sufficient. They are also associated with fewer side effects and lower costs [10] [11] [12].

Dermatomycosis (DM) is the medical term for a fungal infection of the skin.

Causes

The most common DM is that known as athlete's foot. Here, fungi thrive in the warm, humid microclimate of toes and spaces between the toes. Many patients contract this disease in public pools or showers, where there are a high pathogenic load and sufficient humidity. Once the fungal pathogen infected the skin of the foot, it may easily be transmitted to other areas of the body, e.g., to nails, hands, head, and groin. However, an athlete's foot is not an absolute requirement to develop those pathologies and a patient may contract them as single entities.

Symptoms

Symptoms vary with the fungal pathogen and with the area of the body affected by DM. Many DM are associated with scaly, reddened skin and itching. The skin might look chapped and lose hair if any is present. A very common presentation of DM is that of the ringworm. It manifests in form of red, round or ring-shaped, itching rashes.

Diagnosis

While the clinical picture may indicate a DM, it is always better to directly prove the presence of a fungal agent. Therefore, the physician will obtain skin, hair or nail samples, analyze them under a microscope and possibly establish a fungal culture.

Treatment

Drug therapy is indicated to eliminate the pathogen from the skin. Focal, uncomplicated DM are usually treated with antimycotics for topical use, e.g., creams, ointments or nail polish. Non-responsive cases or these that initially present as extensive infections may be treated with systemic antifungal drugs. Any therapy should be continued until two weeks after complete resolution of symptoms if relapses are to be avoided.

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