Epidermophytosis of the feet

Athlete's foot is a chronic infectious disease. It often begins in teenagers or young adults. Men are more likely to get sick. The disease occurs in almost all countries of the world.

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Causes of athlete's foot

The causative agent of the disease is mainly Tr. rubrum (80-85%). Trichophyton interdigitale accounts for 10-20% of all pathogens causing foot mycosis. Infection occurs through direct contact with a sick person (shared bed), but more often indirectly: when wearing shoes, socks, stockings of a patient suffering from athlete's foot, as well as in baths, showers, swimming pools, gyms, where exfoliated epidermis and fallen particles of nails destroyed by the fungus of patients can get on the damp skin of the feet of a healthy person. Risk factors include hyperhidrosis, flat feet, insufficient hygiene care, wearing tight shoes.

In human skin scales, arthrospores remain viable for more than 12 months.

The penetration of fungal infection into the skin is facilitated by a violation of the integrity of the epidermis (microtrauma, abrasion, diaper rash), microcirculation of the lower extremities, endocrine (diabetes mellitus), immune system, long-term use of cytostatics, glucocorticosteroids and antibiotics.

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Histopathology

In the squamous form of epidermophytosis, acanthosis and hyperkeratosis are observed. The horny layer is 2-3 times thicker than the rest of the epidermis; the shiny layer is usually absent.

In the dyshidrotic form, significant acanthosis, hyperkeratosis, focal parakeratosis are observed; in the Malpighian layer - intercellular edema with a large number of bubbles - exocytosis, in the upper layers of the dermis - edema, perivascular inflammatory infiltration of lymphocytes, histiocytes, fibroblasts and neutrophilic granulocytes. Threads and chains of fungal spores are found in the horny and spinous layers of the epidermis.

In onychomycosis, parakeratosis, smoothing of the dermal papillae, edema in the reticular layer, infiltrates of lymphoid cells and histiocytes around the vessels are observed in the nail bed. Fungal elements are found in the horny and parakeratotic masses of the nail bed.

Symptoms of athlete's foot

The incubation period is not precisely established. There are several forms of mycosis: squamous, intertriginous, dyshidrotic, acute and onychomycosis (nail damage). Secondary skin rashes are possible - eiidermophytides (mycids), associated with the allergenic properties of the fungus.

In the squamous form, peeling of the skin of the arch of the foot is observed. The process can spread to the lateral and flexor surfaces of the toes. Sometimes areas of diffuse thickening of the skin are formed, like calluses, with lamellar peeling. Usually, patients do not complain of subjective sensations.

The intertriginous form begins with barely noticeable peeling of the skin in the third and fourth interdigital folds of the feet. Then there is diaper rash with a crack in the depth of the fold, surrounded by a peeling, whitish, horny layer of the epidermis, accompanied by itching, sometimes burning. With prolonged walking, cracks can transform into erosions with a wet surface. In the case of the addition of pyogenic flora, hyperemia, swelling of the skin develop, itching increases, and pain appears. The course is chronic, exacerbations are observed in the summer.

In the dyshidrotic form, blisters with a thick horny cover, transparent or opalescent contents ("sago grains") appear. Blisters are usually located in groups, tend to merge, forming multi-chamber, sometimes large blisters with a tense cover. They are usually localized on the arches, lower lateral surface and on the contact surfaces of the toes. After their opening, erosions are formed, surrounded by a peripheral ridge of exfoliating epidermis. In the case of a secondary infection, the contents of the blisters (vesicles) become purulent and lymphangitis and lymphadenitis may occur, accompanied by pain, general malaise, and an increase in body temperature.

Acute epidermophytosis occurs as a result of a sharp exacerbation of the dyshidrotic and intertriginous forms. It is characterized by a rash of a significant number of vesicular-bullous elements on the edematous inflamed skin of the soles and toes. Lymphangitis, lymphadenitis, severe local pain that makes walking difficult, and high body temperature are noted. Generalized allergic rashes may appear on the skin of the trunk. In clinical practice, a combination or transition of the above-described forms is noted in the same patient.

When the nails are affected, the nail plates (often the fifth toes) become dull, yellowish, uneven, but retain their shape for a long time. Yellow spots or ochre-yellow stripes are noted in the thickness. Over time, most patients develop subungual hyperkeratosis and destruction of the nail plate occurs, accompanied by "eaten away" of its free edge. Fingernails are almost not affected.

Differential diagnosis

The decisive role belongs to the results of microscopic and cultural studies. Clinically, the disease should be distinguished from rubrofitia, superficial pyoderma, contact dermatitis; the intertriginous form - from candidiasis and diaper rash of small folds.

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