Foot fungus is a widespread fungal lesion of the skin and nails of the feet. Depending on the clinical form, it may manifest as red plaques, spots and flat papules with whitish peeling on the surface, bubbles, cracks, erosions, the appearance of yellow stripes and spots on the nail plate, its thickening or rejection. Diagnostics includes dermatoscopy, luminescent examination, determination of skin pH, microscopy of scraping for pathogenic fungi, detection of concomitant diseases of the feet. Treatment is carried out by systemic and local application of antifungal agents with preliminary exfoliating or anti-inflammatory therapy.
B35.3 Feet mycosis
Foot fungus is a common fungal disease spread all over the world. According to some data, about 10% of the world’s population has epidermophytosis of the feet. Up to 80% of the sick are certain professional categories of the population: workers of baths and hot shops, athletes, miners, etc. Cases of foot fungus are noted mainly among the adult population, and in the city more often than in rural areas.
The occurrence of foot fungus is associated with infection with the fungus Trichophyton mentagrophytes, which is also a causative agent in nail epidermophytosis and inguinal epidermophytosis. The transmission of the fungus from sick people to healthy people occurs by contact through public objects, in public baths, swimming pools, saunas, gyms and showers. The spores of the fungus and its mycelium are located in the exfoliated scales of the stratum corneum of the epidermis, which are abundantly lost by the patient with epidermophytosis of the feet. Caught in this way on shoe insoles, shower mats, washcloths or rugs, the fungus is able to persist there for a long time, especially in warm and humid climates.
Infection with the fungus Trichophyton mentagrophytes does not lead to the appearance of foot fungus in all people. The development of the disease is favored by various trophic disorders of the lower extremities, which can be observed when:
- diabetes mellitus;
- varicose veins with chronic venous insufficiency,
- deep thrombosis of peripheral vessels;
- vegetative-vascular dysfunction.
Increased sweating of the feet, narrowed interdigital spaces, flat feet, alkaline sweat reaction can contribute to the appearance of foot fungus.
Modern clinical dermatology distinguishes five variants of foot fungus: squamous, intertriginous, dyshydrotic, erased and epidermophytic nails. These forms can be combined with each other or pass into one another. Separately, the so—called epidermophytides are isolated – rashes of an allergic nature caused by the sensitization of the body to the antigens of the fungus Trichophyton mentagrophytes.
It is manifested by the appearance on the skin of the arch of the foot or its lateral surfaces of flat papules or plaques of reddish color with whitish-gray peeling. The lesions have clear boundaries and may resemble plaques typical of psoriasis. At the periphery, they are surrounded by a border of exfoliating epidermis with single small bubbles. Often peeling elements are combined with hyperkeratosis phenomena in the form of yellow corns with cracks on the surface, resembling manifestations of traumatic dermatitis. Moderate and intermittent itching is characteristic.
Most often affects the interdigital spaces of the III and IV, IV and V fingers, can pass to their flexor surfaces. It is manifested by foci of redness, swelling and wetness of the skin, maceration and cracks, the appearance of erosions. Patients note itching in the lesions and soreness during the formation of erosions.
It is characterized by the appearance of small bubble rashes. Their most frequent location is the arch of the foot, at the same time, the skin of the soles, fingers and interdigital folds can be affected. The bubbles increase, merge and form multi-chamber bubbles, after opening which red-pink erosions remain on the skin. Soreness and itching are noted. With a pronounced inflammatory component, swelling and redness of the skin occur, which make the clinical picture of foot fungus similar to dyshidrotic eczema.
The erased fungus of the foot has an inconspicuous symptomatology in the form of a small crack or a peeling focus located in the interdigital space. Epidermophytia of nails is manifested by their yellowness, thickening, brittleness or rejection of the nail plate. The nails of the I and V fingers are most often affected.
Wetness, erosion and cracks of the skin, which often occur with foot fungus, favor the penetration of streptococcal infection into the skin with the development of streptoderma, erysipelas, thrombophlebitis, phlebitis, lymphangitis or lymphadenitis.
Diagnosis is carried out by a mycologist or dermatologist. As a rule, it consists in examining the lesions using dermatoscopy, conducting fluorescent diagnostics with a Wood lamp, determining the pH of the skin. Microscopy of scraping from the skin and the affected nail plate is carried out to identify the filaments of mycelium or fungal spores that need to be differentiated from the mesh or loop-like structures of the mosaic fungus, which are products of the breakdown of cholesterol in the skin. Microscopic examination does not give an answer to the question of which kind of fungus is the causative agent.
For the differential diagnosis of Trichophyton mentagrophytes from pathogens of other fungal diseases (rubromycosis, candidiasis, pityriasis, coccidiomycosis, etc.), scraping is also carried out on nutrient media. Diagnosis of concomitant foot fungi diseases may require additional consultation of a podologist, orthopedist, vascular surgeon, phlebologist or endocrinologist.
Foot fungus therapy is carried out in 2 stages. At the preparatory stage, with the squamous form of the disease, scales and hyperkeratic layers are removed, with dyshidrotic and intertriginous foot fungus, acute inflammation is removed. In the first case, keratolytic agents are used (lactic and salicylic acid, soap and soda baths for feet), in the second – anti-inflammatory and antihistamines. With epidermophytosis of the nails, surgical removal of the nail affected by the fungus is performed.
The main stage of treatment of foot fungus is the treatment of the affected areas of the skin and / or the bed of the removed nail plate with antimycotic agents (nirofungin, Castellani liquid, ointments with miconazole, clotrimazole, etc.). With persistent and prolonged course of foot fungus, accompanied by nail damage, systemic administration of antifungal drugs is indicated: itraconazole, fluconazole, terbinafine, ketoconazole et al.