Mycosis of the feet

Mycosis of the feet (mycosis pedis) is a skin lesion of the feet caused by some dermatophyte and yeast fungi, which has a common localization and similar clinical manifestations.

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Cause and epidemiology of athlete's foot

Mycosis of the feet is one of the first places among skin diseases. The most common causative agents of mycosis of the feet are red trichophyton (Trichophyton rubrum) and interdigital trichophyton (Trichophyton mentagrophytes, var. interdigitaie), less often this disease is caused by yeast-like fungi of the genus Candida and Epidermophyton floccosum. Infection occurs most often in baths, showers, swimming pools, gyms with insufficient observance of sanitary and hygienic rules for their maintenance, as well as on beaches when the skin of the feet comes into contact with sand contaminated with scales. Wearing impersonal shoes without prior disinfection, using shared towels can also lead to infection. Pathogens are extremely resistant in the external environment: they can grow on wood, shoe insoles, persist for a long time in socks, stockings, gloves, on towels, as well as on bath equipment. Mycosis of the feet usually recurs in spring and autumn and can lead to temporary loss of ability to work.

Pathogenesis of mycosis of the feet

Mycosis of the feet develops in the presence of predisposing exogenous and endogenous factors that favor the introduction of the fungus. Exogenous factors include abrasions, increased sweating of the feet, which increases when wearing socks made of synthetic fibers, tight, unseasonably warm shoes and leads to maceration of the stratum corneum on the feet. Endogenous causes are associated with impaired microcirculation in the lower extremities (with atherosclerosis, obliterating endarteritis, varicose symptom complex, vegetative imbalance, Raynaud's symptom complex), endocrine pathology (obesity, hypercorticism, diabetes mellitus, etc.), hypovitaminosis, immunosuppression - congenital or acquired (for example, HIV infection, intake of corticosteroids, cytostatic, antibacterial, estrogen-gestagen drugs, immunosuppressants).

Symptoms of athlete's foot

Depending on the inflammatory response and localization of lesions, five clinical forms of mycosis of the feet are distinguished: erased, intertriginous, dyshidrotic, acute, squamous-hyperkeratic. Often, a combination of these can be found in one patient.

The erased form usually manifests itself as slight peeling in the III-IV interdigital transitional folds of the feet and is accompanied by minor inflammatory phenomena. Sometimes a small superficial crack can be found in the depth of the affected interdigital fold. Minor peeling can also be expressed in the area of the soles and lateral surfaces of the feet.

The intertriginous form resembles diaper rash. In the interdigital transitional folds of the feet, in places of friction of the contacting surfaces of the fingers, maceration of the stratum corneum occurs, masking the hyperemia of the affected skin. An eruption of blisters is also possible. This leads to exfoliation of the epidermis with the formation of erosions and cracks in the interdigital folds. A whitish swollen epidermis hangs over the edges of the erosions in the form of a collar. The lesion is accompanied by severe itching, sometimes pain. This form of the disease can be complicated by pyogenic infection: swelling and redness of the skin of the fingers and the dorsum of the foot, lymphangitis, regional adenitis appear. Much less often, this form of mycosis of the feet is complicated by erysipelas and bullous streptoderma.

The dyshidrotic form is characterized by a rash of grouped blisters on the skin of the arches and lateral surfaces of the feet. On the arch of the foot, they shine through a thinner stratum corneum, resembling boiled rice grains in appearance and size. Blisters often appear on unchanged or slightly reddened skin, increase in size, merge, forming larger multi-chamber cystic elements. When a secondary infection occurs, the contents of the blisters become purulent. The rash is accompanied by itching and pain. After the blisters open, erosions with fragments of epidermal covers along the edges are formed. The disease may be accompanied by vesicular allergic rashes, mainly on the hands (mycosis), resembling eczematous manifestations. As the process subsides, the rash of fresh blisters stops, the erosions epithelialize, and slight peeling remains in the lesions. The dyshidrotic form of mycosis and the accompanying mycosis on the palmar surface should be distinguished from dyshidrotic eczema and allergic dermatitis, as well as from true dyshidrosis.

Acute form of mycosis of the feet was identified by O. N. Podvysotskaya. This rare form of mycosis occurs as a result of a sharp exacerbation of dyshidrotic or intertriginous varieties of the disease. A high degree of sensitization of the skin to fungal allergens develops most often with irrational therapy of these forms of mycosis of the feet. Excessive fungicidal therapy causes a sharp increase in inflammatory and exudative changes in the foci of mycosis and outside the foci. Increased sweating of the feet, their prolonged maceration and abrasions also predispose to this. Pyogenic flora naturally takes part in the process, complicating mycosis and causing additional sensitization. The acute form of mycosis is caused mainly by interdigital trichophyton, which has a pronounced allergenic effect. The disease begins acutely with the formation of a large number of blisters and vesicles on the skin of the feet and then the shins against the background of edema and diffuse hyperemia. Soon vesicular and bullous elements appear on the skin of the hands and lower thirds of the forearms. These rashes are symmetrical. No fungal elements are found in them, since they have an infectious-allergic genesis. After the opening of the cavitary elements, erosions are formed, surrounded by scraps of the macerated horny layer. In places, the erosions merge to form extensive diffusely moist surfaces, often with purulent discharge. The disease is accompanied by an increase in body temperature, a deterioration in the general condition of the patient, and sharp pains in the affected feet and hands. The inguinal and femoral lymph nodes enlarge and become painful. When making a diagnosis, it should be borne in mind that the acute form of mycosis of the feet resembles eczema of the feet and hands, a bullous variety of erythema multiforme.

The squamous-hyperkeratotic form of mycosis of the feet is characterized by focal or diffuse thickening of the stratum corneum of the lateral and plantar surfaces of the feet. The affected areas of the skin usually have a weakly expressed inflammatory coloration and are covered with small bran-like or flour-like scales. Peeling is especially noticeable in the skin grooves, which gives the skin a powdery appearance. Some patients complain of itching in the affected areas. Cracks cause pain when walking. With this form of mycosis of the feet, which is most characteristic of red trichophyton, mycids usually do not occur.

Diagnosis of mycosis of the feet

The diagnosis is established on the basis of the characteristic clinical picture and the results of mycological examination (detection of mycelium and obtaining a fungal culture).

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Treatment of mycosis of the feet

External therapy with substances with fungicidal activity and a broad spectrum of action, such as azoles, allylamines, ciclopirox and amorolfine derivatives, is recommended.