Etiology Also known as otomycosis, it is a subacute or chronic inflammatory disease of the skin of the external ear canal, mostly thought to be caused by fungal infections, often combined with bacterial infections. The disease occurs in tropical or subtropical regions and is common during hot and humid seasons. Most believe that fungal infection is the direct causative factor. Pathogenic fungi are mainly Aspergillus, accounting for about 80% to 90%; other more for Penicillium, broomstick, Trichoderma, Rhizopus and Candida, etc. Pathogenic dermatophytes are rare. The most common co-infection bacteria are Staphylococcus aureus, Streptococcus hemolyticus, Pseudomonas aeruginosa, Proteus mirabilis, Escherichia coli, etc. The predisposing factors of this disease are: 1. The increase of ambient temperature and humidity is favorable for the growth and reproduction of fungi. 2. Cerumen has the function of inhibiting the growth of fungi, and the lack of cerumen is favorable to the reproduction of fungi. 3. Chronic purulent otitis media is prone to combined fungal infections, some of which may be related to the long-term use of broad-spectrum antibiotic solutions in the ear. 4. Ear trauma caused by ear digging. Clinical manifestations In early stages of the disease or in mild cases, the patient may not have any symptoms and may be found incidentally during physical examination. After the fungus has invaded the epithelium, itching, discomfort and stuffiness in the ear may occur. If the outer ear canal is obstructed by a scab composed of shed epithelium and mycelium, or if it comes into contact with the tympanic membrane, it causes tinnitus and hearing loss. When the combined bacterial infection invades the subepithelial layer and the infection worsens, in addition to ear overflow and ear itching, there is also obvious ear pain and foul odor in the ear. Examination reveals that in the early stage, dense accumulation of powdered or granular material or fluffy material adhering to the deep skin and scaly flakes of the external auditory canal is seen, which is white, yellowish, yellowish-brown or green in color and can be easily swabbed away, but soon reappears. If there is pus or scab in the external auditory canal or mastoid cavity after radical surgery, mycelium may be seen on the scab. In severe cases, secretions can be seen in the external auditory canal, with deep yellowish-brown or black cylindrical or membrane-like necrotic material, and the skin can be seen to be congested, swollen and eroded after removal. In chronic infections, eczema-like changes and mossiness can be seen, and in severe cases, narrowing of the external auditory canal can be caused. The lesions may also invade the auricle and neck.