A small amount of pus accumulation in the ear canal of auricular ringworm can be directly examined and cultured for bacterial growth, which helps in the diagnosis. Mycelium and spores, sometimes conidia, are visible on examination by taking cerumen or scabs with 10% KOH solution and culture with fungal growth. Tinea capitis needs to be differentially diagnosed from the following diseases: 1. External ear canal neoplasm Benign tumors include external ear canal papilloma, external ear canal cholesteatoma, external ear canal bone wart, hemangioma, fibroma, cerumen adenoma, etc.; malignant tumors include adenocarcinoma, sarcoma, malignant melanoma, etc. In addition, chronic suppurative otitis media can lead to the growth of polyps in the tympanic chamber, and the polyps can prolapse from the tympanic membrane perforation to form a flab in the external ear canal. 2. Foreign body in the external ear canal Most often seen in children, but can also occur in adults. Most of them are caused by ear digging or trauma, and insect invasion. Foreign bodies can be divided into abiotic, plant and animal types. If the foreign body is small and not irritating, it can remain for a long time without symptoms. Large foreign bodies can block the ear canal and cause hearing loss and a feeling of swelling. Sometimes they cause vertigo, tinnitus and ear pain, or cause skin breakdown. In general, foreign bodies are easier to detect on examination.