A middle ear cholesteatoma is a cystic structure located in the middle ear and is not a true tumor. Cholesteatoma can be secondary to chronic suppurative otitis media, and chronic suppurative otitis media can also be secondary to bacterial infection of the cholesteatoma, so the disease can also be called chronic otitis media with cholesteatoma. Because cholesteatoma can destroy the surrounding bone, serious intracranial and extracranial complications can occur and should be taken seriously. Cholesteatoma in the temporal bone can be classified as congenital or acquired. Congenital cholesteatoma is a result of ectodermal tissue left behind during embryonic period or vagal development in the skull, and can be seen in the temporal bone as apices, bullae or mastoids. Acquired cholesteatoma is divided into two types: primary cholesteatoma without a history of purulent otitis media and purulent inflammation of the middle ear after cholesteatoma combined with bacterial infection; secondary cholesteatoma secondary to chronic purulent otitis media or chronic secretory otitis media. The exact mechanism of the formation of acquired cholesteatoma is not clear. As a result, the anterior tympanic isthmus and posterior tympanic isthmus are completely or partially atretic, and two incompatible or incomplete systems are formed between the upper tympanic chamber, the tympanic sinus and mastoid cavity, the middle and lower tympanic chambers and the eustachian tube. As a result of the long-term high negative pressure in the upper tympanic chamber, the loose part of the tympanic membrane sinks into the tympanic chamber, and a pocket retraction is gradually formed there. Because the inner wall of the pouch is composed of the epidermal layer of the tympanic membrane, the epidermal epithelium and keratinized material can be shed continuously; in addition, the epithelium of the external auditory canal loses its self-cleaning ability due to chronic inflammation, and the keratinized material and epithelial debris inside the pouch cannot be discharged. This is known as acquired primary cholesteatoma. Most of these cholesteatomas develop along the neck of the hamate head and the lateral aspect of the anvil bone in the early stage. (2) Epithelial migration theory: In chronic suppurative otitis media with marginal perforation or large perforation of the tympanic membrane, the epithelium of the external auditory canal and tympanic membrane grows along the bony surface of the marginal perforation towards the tympanic cavity and gradually reaches the tympanic sinus, tympanic sinus and mastoid area. (3) Squamous epithelial metaplasia theory: According to this theory, epithelial cells in the middle ear mucosa can metaplasia into keratinized squamous epithelium after being stimulated by inflammation, and then cholesteatoma occurs. (4) Basal cell proliferation theory: It is believed that epithelial cells in the loose part of the tympanic membrane can form epithelial columns by proliferation, and the latter can reach into the subepithelial tissues after destroying the basement membrane and form cholesteatoma on this basis. Pathology Cholesteatoma is a cystic structure rather than a true tumor. The lining of the cyst is compound squamous epithelium, and the cyst is filled with exfoliated squamous epithelium and keratinized material. Both primary and secondary cholesteatomas can destroy the surrounding bone and expand in all directions. The exact mechanism of this destruction of bone is not known, but early on there were theories of mechanical compression, later enzymes (protease, collagenase, acid phosphatase, etc.), or prostaglandins, tumor necrosis factor, lymphokines, etc. In addition, cholesteatoma is often combined with bone ulcers with granulomatous growth or cholesterol granuloma, etc. Symptoms 1. Ear overflow. Secondary cholesteatoma has long-term pus flow in the ear, the amount of pus varies, and the pus often has a special foul odor due to secondary infection by corrosive bacteria. In acquired primary cholesteatoma, there is no pus in the ear in the early stage, and the ear overflow occurs when the infection is combined. 2. Hearing loss. Early limited cholesteatoma in the upper tympanic chamber may be asymptomatic and not cause significant hearing loss. If the auditory chain is disrupted, hearing loss may be the first diagnosis. Secondary cholesteatomas generally have a more severe conductive or mixed hearing loss. Because the cholesteatoma acts as a sound bridge between the defective auditory bones, hearing loss is less pronounced even when the auditory bones are partially destroyed. 3. Tinnitus. High-pitched or low-pitched tinnitus may be present. Tinnitus does not appear in the early stage. Examination 1. Otoscopic examination The tympanic membrane is perforated in the loose part or above the tense part, or the tympanic membrane is perforated in the large part. The perforation may be accompanied by granulation tissue. In early primary cholesteatoma, the perforation of the flaccid part may be covered by a layer of scab, which is not recognized by beginners and is often missed if the scab is not removed and investigated. In large cholesteatomas, the lateral bone wall of the superior tympanic chamber or the posterior superior bone wall of the external auditory canal may be destroyed, or the posterior superior wall of the external auditory canal may collapse. Hearing loss can be mild or severe, and can be conductive or mixed, with a few cases of sensorineural deafness. High resolution CT scan of the temporal bone shows bony destruction of the superior tympanic chamber, tympanic sinus or mastoid process with dense and neat margins. Early surgery should be performed. The purpose of surgical treatment: 1. Complete removal of the diseased tissue. The cholesteatoma, sarcoma and lesioned bone in the mastoid, upper, middle, lower and posterior tympanic chambers and eustachian tube should be completely and thoroughly removed; 2. Reconstruction of the sound transmission structure. On the basis of complete removal of diseased tissues, the healthy tissues related to the sound transmission structure, such as the auditory tuberosity, the residual tympanic membrane, the mucosa of the eustachian tube, the mucosa of the tympanic chamber, and even the intact external auditory canal and the tympanic sulcus, should be preserved as much as possible, and on this basis, the sound transmission structure should be reconstructed at the same time or in a secondary stage.