Superficial fungal infections of the skin between the fingers (toes) and on the palms or metatarsus are called tinea manus (hand ringworm) and tinea pedis (foot ringworm). When the infection affects the fingernails or toenails, it is called tinea unguium (nail ringworm). Among superficial fungal diseases, tinea pedis has the highest incidence rate and is also the root cause of tinea manus, tinea corporis, tinea cruris, and tinea unguium, making active prevention and treatment essential.

bubble_chart Etiology

The main pathogenic fungi of tinea manuum and tinea pedis are Trichophyton rubrum, followed by Trichophyton gypsum and Epidermophyton floccosum. Due to its strong resistance and difficulty in control, Trichophyton rubrum has become the primary pathogen of tinea manuum and tinea pedis. The thick stratum corneum of the metatarsal skin, profuse sweating on the feet, and the absence of sebum all facilitate fungal infection. Wearing non-breathable shoes and humid environments are significant factors in the onset and worsening of the condition. Tinea pedis is often indirectly transmitted, with shared slippers, towels, pedicure tools, and exchanging shoes and socks in public baths being the main vectors of transmission.

bubble_chart Clinical Manifestations

1. Tinea Pedis: Commonly known as "athlete's foot," it is more common in adults. The incidence rate is higher in southern regions. Symptoms are milder in winter and more severe in summer. People who frequently wear rubber shoes have a higher prevalence rate. Clinically, it is divided into four types, but they often coexist with one type predominating. (1) Hyperkeratotic Type: The skin becomes thickened and rough due to hyperkeratosis, often leading to painful rhagades in winter. (2) Vesicular Type: Blisters are usually located on the soles of the feet, with thick walls that are not easily ruptured, and contain clear fluid. They may appear in clusters or scattered. The skin around the blisters is normal. After a few days, the blister fluid is absorbed, and the area becomes dry and scaly. If secondary bacterial infection occurs, pustules may form. This type often presents with cutaneous pruritus. (3) Intertriginous Erosive Type: The affected skin becomes moist, softened, and whitish. When the epidermis is rubbed off, a red erosive surface is exposed. It commonly occurs between the third and fourth toes. Intense cutaneous pruritus is often present. Scratching can lead to secondary bacterial infections such as lymphangitis, lymphadenitis, erysipelas, or cellulitis. This type often has a foul odor. (4) Papulosquamous Type: Lesions are found on the soles, edges, and heels of the feet, presenting as erythema and papules with noticeable small scaly patches. Blisters may appear in summer. When the lesions extend to the dorsum of the foot, they manifest as annular erythema with scales and edges featuring blisters or papules, resembling tinea corporis.
2. Tinea Manuum: Commonly known as "goose-web wind (tinea manuum)." The lesions are largely similar to those of tinea pedis. It often starts on one hand, and if both hands are affected, the initially affected hand tends to have more severe symptoms. The lesions are primarily vesicular or hyperkeratotic, while the intertriginous erosive type is less common. In winter, the affected skin becomes rough and thickened, prone to rhagades. In summer, blisters may form, often rupturing to create a collarette of scales. Cutaneous pruritus is frequently present. The condition is chronic and may persist for many years without healing. Due to misdiagnosis or mistreatment, the lesions often become eczematized.
3. Onychomycosis: Commonly known as "onychomycosis." It usually begins with one or two fingernails or toenails. In severe cases, all nails may be affected. The affected nails lose their luster, become thickened and deformed over time, and turn grayish-white or dirty yellow. The nails become brittle, break, and may fall off. Sometimes, the nail plate separates from the nail bed.
4. Dermatophytids: These are allergic rashes caused by dermatophytes and their metabolic byproducts. Tinea pedis patients are the most common cause of dermatophytids. The lesions typically manifest in three types: dyshidrotic, erysipelas-like, and lichenoid papular. Fungal tests on the lesions are negative, but the dermatophytin test is positive.

bubble_chart Diagnosis

The diagnosis can be confirmed based on clinical manifestations and a positive direct microscopic examination for fungi.

bubble_chart Treatment Measures

1. Tinea Manuum and Pedis: Local treatment is the main approach, and different dosage forms of antifungal drugs can be selected based on the type:
   1. Vesicular Type: Tinctures such as compound benzoic acid alcohol, compound pseudolaric acid tincture, or Xinpixianjing (main ingredients include salicylic acid, benzoic acid, iodine, azone, etc.) can be used.
   2. Maceration and Erosion Type: If there is little exudate, powders such as foot powder or Zushuang powder (main ingredients include Chinese medicinals litharge, borneol, calamine, etc.) can be used. If there is abundant exudate or secondary infection, a 1:5000–1:8000 potassium permanganate solution or 0.1% rivanol solution should be used to soak the affected foot 1–2 times daily. After the skin lesions dry, creams or powders can be applied. Antibiotics may also be used as needed.
   3. Papulosquamous Type: Creams such as clotrimazole, miconazole (Daktarin), or compound miconazole can be selected.
   4. Hyperkeratotic Type: Ointments such as compound benzoic acid ointment can be used.
2. Onychomycosis: The affected nail must first be removed. Methods include surgical nail avulsion, 40% urea nail dissolution, or daily soaking of the affected nail in hot water to soften it, followed by scraping with a small knife. After removal, topical 2.5% iodine tincture or Xinpixianjing can be applied to eliminate residual fungi on the nail bed until the new nail fully grows.
3. Dermatophytid: The primary lesion (e.g., tinea pedis) should be actively treated. Once the primary lesion resolves, the skin rash will also subside. Antihistamines may be taken concurrently, and symptomatic local treatment can be applied.

bubble_chart Prevention

The key to preventing athlete's foot is to keep the feet ventilated, dry, and reduce humidity. Pay attention to personal and collective hygiene.