Cholesteatoma of the external auditory canal is a mass of exfoliated epithelium containing cholestatic crystals in the bony segment of the external auditory canal. It is thought to be associated with long-term irritation of the skin of the external auditory canal by various pathologies (e.g. cerumen embolism, inflammation, foreign bodies, fungal infections, etc.). The skin of the external auditory canal becomes chronically congested and the shedding of keratinized epithelial cells is accelerated. If there is some reason why the shedding epithelium cannot be discharged from the external auditory canal in time, the keratinized material of the skin increases and agglomerates into a mass, which can obstruct the external auditory canal. In the long run, the center of the skin becomes corrupted, decomposed and denatured, producing cholesterol crystals. As the cholesteatoma grows in size, it can cause compressive bone destruction. In addition, the cholesteatoma produces a proteolytic enzyme that causes the bone to dissolve, and the two interact to enlarge the external auditory canal cavity. It is also thought that the disease is associated with congenital defects in the respiratory mucosa and the skin of the external auditory canal or excessive secretion of cerumen glands. Cholesteatoma of the external auditory canal develops slowly and has a long course. Symptoms are related to the size of the cholesteatoma and the presence of co-infection. Small uninfected cholesteatomas often have no obvious symptoms and are easily ignored by patients. In larger tumors, a feeling of ear obstruction, hearing loss, and tinnitus may occur. If the cholesteatoma swells and compresses the external ear canal, it can cause severe ear pain if the ear canal becomes infected due to water or other causes. This is often the main reason for patients to visit the clinic. In this case, it is important not to misdiagnose the problem as cerumen embolism and repeatedly soak it, aggravating the infection. In case of infection, bacteria can break down the cholesteatoma, and the liquefied material mixed with the otitis externa exudate will overflow and form an ear leak, which is often accompanied by bad odor. If there is granulation, the secretion may contain blood. Individual external auditory cholesteatoma may invade the mastoid via the posterior wall of the external auditory canal and extensively destroy the mastoid bone, resulting in cholesteatoma mastoiditis of the middle ear; the vertical segment of the facial nerve and the bulbar nerve may also be exposed directly below the lesion due to bone destruction. The vertical segment of the facial nerve and the tympanic nerve may be exposed directly below the lesion due to bone destruction. For small cholesteatomas without infection, they can be removed on an outpatient basis. However, repeated immersions causing infection should be avoided. In cases of secondary infection, the cholesteatoma cannot be seen at all because of skin swelling at the osteochondral junction of the external auditory canal, granulation, or even polyp formation, and the pain in the affected ear is intolerable to the touch. Infection of the external auditory canal in such cases can only be controlled after the cholesteatoma is removed. Because the significantly enlarged bony external auditory canal has lost its normal curvature, cerumen and epithelial debris are difficult to drain naturally, and new cholesteatomas may form again, so regular follow-up cleanup should be performed after surgery.