Tinea corporis is a dermatophyte infection of the skin of the trunk and extremities except for the hair, palmoplantar, nails and groin. It is endemic worldwide and is most common in tropical regions. It can be transmitted from person to person, animal to person, and soil to human. Domestic animals most often cause ringworm. Other susceptibility factors include having ringworm of the head or feet themselves, or having close contact with the patient, contact with contaminated clothing or furniture, immunosuppression, occupational exposure, or recreational exposure. It often occurs in exposed areas, but can spread to any part of the body surface. The incubation period for tinea corporis is usually 1 to 3 weeks. The infection spreads centrifugally from the site of skin invasion and fades centrally to form typical ring-shaped lesions of varying size, which can also be bow-shaped, spiral-shaped, etc. The lesions are mostly scaly, and if topical glucocorticoid preparations are applied topically, the scaling will decrease or disappear (difficult to identify ringworm, Xiao Wu belongs to this type). Self-perceived itching and burning sensation. The diagnosis can be confirmed by scraping the scales from the edges of the lesions for direct fungal microscopy and finding mycelium and arthrospores. Fungal culture helps to identify the causative organism, which is very useful for the source of the causative organism and the selection of appropriate treatment. The clinical symptoms of eczema and ringworm are similar, and the main points of differentiation are: 1. From the appearance of the rash, ringworm is mostly circular in shape due to the body’s defenses, and the center can be self-healing and flaky or pigmented, while the edges can be raised with active erythema, papules and blisters, while eczema does not have this phenomenon; 2. From the arrangement of the rash, ringworm is mostly asymmetric, while eczema is mostly symmetrically arranged; 3. The active rash of tinea corporis can be tested for fungi, while eczema does not. In short, eczema can be easily confused with ringworm, and it is sometimes difficult for patients to identify them visually, while the treatments for the two are different, so it is recommended that such patients go to a regular hospital for treatment. The author speculates that Xiao Wu’s misdiagnosis at a major hospital in our city may be related to not choosing an active rash for testing.