What Is a Cholesteatoma?

It is generally believed that the incidence of intracranial cholesteatoma is 0.5-1.8% of whole brain tumors. Can be multiple shots, ranging in size from a few millimeters to several centimeters. It can occur at any age, with a peak age of 40 years. Slightly more men than women, about 1.25: 1. Symptoms usually appear in adulthood, with the most common onset in 20-50 years old, accounting for over 70%. May be associated with skin fistula, spina bifida, syringomyelia, and skull base depression.

Fan Xiaotong	(Resident)	Department of Neurosurgery, Xuanwu Hospital, Capital Medical University
Xu Geng	(Chief physician)	Department of Neurosurgery, Xuanwu Hospital, Capital Medical University

Cholelipoma is also called epidermoid cyst, pearloma and so on. At present, it is thought to be a benign tumor with congenital avascular disease derived from the residual ectodermal tissue of an ectopic embryo. Occurs in the brain and ears. According to the location of cholesteatoma, it can be divided into intracranial cholesteatoma, external auditory canal cholesteatoma, and cholesteatoma otitis media. It is generally believed that the incidence of intracranial cholesteatoma is 0.5-1.8% of whole brain tumors. Can be multiple shots, ranging in size from a few millimeters to several centimeters. Cholelipoma is usually removed by surgery.

Western Medicine Name: Cholesteatoma
Affiliated Department: Surgery-Neurosurgery

Contagious: Non-contagious
Whether to enter health insurance: Yes

Introduction to cholesteatoma disease

The etiology of the external auditory canal cholesteatoma is unknown. It may be caused by long-term irritation of the external auditory canal skin (such as iliac embolism, inflammation, foreign body, fungal infection, etc.) and chronic congestion. Epithelial cells fall off abnormally. If their discharge is blocked, they accumulate in the external ear canal and form clumps. For a long time, its center was corrupted, decomposed, and denatured, and cholesterol crystals were produced. External auditory canal cholesteatoma can be complicated by cholesteatoma type middle ear mastoiditis, and can also cause peripheral facial paralysis.

Cholelipoma otitis media is often closely related to chronic significant suppurative otitis media. The middle ear is inflamed for a long time, and the tympanic membrane is corroded by pus and perforated. The outer ear canal epidermis can easily enter the middle ear cavity and mastoid cavity along the perforation. The epithelial layer is keratinized, repeatedly falling off, accumulating, and compressing the surrounding bone, causing it to absorb and form a cavity. And bacterial reproduction correctly produces lactic acid, which further corrodes the surrounding bone, leading to the spread of reincarnation inflammation. The left and right middle ears and mastoids, which are the most common sites, increase in pressure with the increase in cholesteatoma. Once the bone wall is broken, pus and bacteria can enter the skull through this. Intracranial complications, such as dural abscess, sigmoid sinus thrombophlebitis, suppurative meningitis, and brain abscess.

Cholelipoma disease classification

According to the location of cholesteatoma, it can be divided into intracranial cholesteatoma, external auditory canal cholesteatoma, and cholesteatoma otitis media.

Intracranial cholesteatoma is one of the important diseases involved in neurosurgery. Common classifications include:

Epidermoid cysts of the cerebellopontine angle: about 70% develop with trigeminal neuralgia. A few have onset of facial muscle twitching, decreased facial sensation, tinnitus, and deafness. According to clinical manifestations, it is divided into three types: simple trigeminal neuralgia type, pontine cerebellar horn tumor type (mainly manifested by tinnitus, dizziness, facial muscle convulsion, and pontine cerebellar horn syndrome including VII and VIII nerve involvement), and increased intracranial pressure .

Epidermoid cysts in the middle cranial fossa: mainly manifested as symptoms of trigeminal nerve palsy, such as decreased facial sensation, weakness in masticatory muscles, etc. Sometimes, vision, visual field disorders, and eye movement disorders also occur. 50% can form riding in the middle cranial fossa, posterior cranial fossa.

Epidermoid cysts in the saddle area: mainly progressive vision, visual field damage, and optic nerve atrophy may occur in advanced stages. Endocrine disorders are rare, and individual sexual dysfunction may occur, such as polydipsia and polyuria.

Epidermoid cysts in the brain parenchyma: seizures, progressive paresis, etc. may occur.

Intraventricular epidermoid cysts: Mostly located in the lateral ventricle triangle and body, there may be no obvious symptoms in the early stage. As the cyst increases, fluctuating or paroxysmal headaches may occur. When the cerebrospinal fluid circulation is blocked, increased intracranial pressure may occur. symptom. Some can be manifested as Brun sign and forced head position. Those who develop to the outside of the brain can show paresis, hemiopia, and hemiplegia. People with four ventricles can cause walking instability.

The late stage of epidermoid cysts in the pineal region are mainly manifested by Parinaud syndrome, such as increased intracranial pressure, difficulty in visualizing both eyes, disappearance of pupils' reflection of light, and existence of regulatory reflexes.

Causes of cholesteatoma

Overall, cholesteatomas are classified into congenital and acquired. The former is thought to originate from embryo-derived residual epithelium, which is common in petrous apex, mastoid, and middle ear. Acquired cholesteatoma is divided into two types: secondary to chronic suppurative otitis media is called acquired cholesteatoma, and secondary to middle ear exudate is called acquired primary cholesteatoma.

Intracranial cholesteatoma is currently thought to be caused by the mixture of ectodermal components when the neural tube is closed during the embryonic period (3-5 weeks of gestation). Trauma is also considered to be one of the causes of cholesteatoma.

Pathogenesis of cholesteatoma

There are several explanations for the causes of extracranial cholesteatoma:

Cholesteatoma negative pressure depression theory

Eustachian tube dysfunction and recurrent otitis media result in negative pressure in the tympanum, slack or tense parts of the tympanic membrane, and the external auditory meatus epithelium loses its migration function due to repeated inflammation. The keratinized epithelium that has fallen off accumulates in the sack, forming bile lipid tumor.

Cholesteatoma epithelial invasion theory

Necrotizing otitis media can cause marginal perforation of the tympanic membrane and necrosis of the tympanic mucosa. Epithelial tissue of the tympanic membrane and external auditory meatus can be migrated to the tympanic cavity to repair the exposed tympanic wound surface and form cholesteatoma.

Cholesteatoma basal cell hyperplasia

Basal cells can invade the subepithelial tissue through columnar hyperplasia, forming cholesteatoma.

Cholesteatoma metaplasia

Chronic inflammation stimulates the middle ear mucosal epithelium to metamorphose into keratotic flat epithelium, forming cholesteatoma.

Intracranial cholesteatoma is mainly considered to be a mixture of ectodermal components when the neural tube of the embryonic stage is closed, which gradually results in tumor formation.

Cholesteatoma pathophysiology

The surface of the tumor was covered with a thin phenanthrene membrane, with a white pearly luster, and a thin layer of fibrous connective tissue under the microscope. The inner surface was stratified squamous epidermal cells, rich in keratinocytes, and the inside was a row of detached cell shells. Inside are some polygonal cells with cell debris and lipid crystals in the center. As the epithelium continues to shed keratinized cells towards the sac, the cyst contents gradually increase and the tumor grows.

The most common sites are the cerebellar pontine angle, parasaddle, fourth ventricle, lateral ventricle, brain, and cerebellum. It rarely occurs in the brain stem. It can also occur in skull plates and spine.

This tumor grows slowly, but it can cause damage to surrounding tissues, cause symptoms, or cause recurrent attacks such as aseptic meningitis.

Clinical manifestations of cholesteatoma

It is generally believed that there is no gender difference in its incidence, and it can occur widely at any age, but the peak incidence is still at the age of 40. Generally the disease progresses slowly. Its clinical symptoms vary depending on the location of the tumor.

Cerebellar pontine angle location, this part is the most common, mostly with trigeminal neuralgia, may have tinnitus and deafness on the affected side, and can gradually develop into cerebellopontine angle syndrome. The signs are C, VII and VIII cranial nerve dysfunction, weakened facial sensation, facial muscle weakness, hearing loss, ataxia, etc. A few may appear paralysis of glossopharyngeal and vagus nerves.

Cholestamas in the saddle area are often similar to pituitary tumors, with early manifestations of vision loss, visual field defects, and even advanced optic nerve atrophy. However, due to the slow progress of the general condition, severe vision loss and blindness are relatively rare. Endocrine disorders can also occur, such as hyposexual function, polydipsia, polydipsia, and other hypophyseal insufficiency and symptoms of hypothalamic damage. As the tumor grows, it can grow forward leading to frontal lobe symptoms, and can project backward into the third ventricle, resulting in increased intracranial pressure. People near the saddle can also expand to the middle cranial fossa, involving pain in the trigeminal ganglion, numbness, weakness of the temporal and masseter muscles, etc.

When located in the parenchyma of the brain, tumors in the hemisphere of the brain often have seizures, psychiatric symptoms, and disorders of limb movement on one side, while the cerebellum often causes nystagmus and ataxia. Brainstem tumors may appear cross paralysis, the affected side VI, VII cranial nerve palsy and contralateral forced paresis.

Intraventricular cholesteatoma is more common in the lateral ventricle triangle and temporal angle, and can be larger and even fill the ventricle. Symptoms of increased intracranial pressure due to blocked cerebrospinal fluid circulation. Relatively speaking, it is rare in the third and fourth ventricles.

When located on the skull surface, tumors can occur anywhere in the skull, but they are more common at the midline or near-midline. Can be found by accident, showing a swollen skull surface, tougher, and generally no tenderness. Because it is located at the midline, it can expand into the skull and involve the sinuses or deep into the brain.

Diagnosis and differential diagnosis of cholesteatoma

Cholelipoma diagnosis

The clinical manifestations of patients vary greatly depending on the location of the tumor, so medical history and physical examination often have greater significance for localized diagnosis. In qualitative diagnosis, objective auxiliary examinations are often required for final confirmation.

Cerebrospinal fluid tests in most patients were normal.

Head X-ray

It has basically been eliminated clinically, and a small number of cholesteatomas of the cerebellar pontine horn or middle cranial fossa can show the destruction or calcification of the petrous apex or petrous callus. However, the skull of cholesteatoma in lamina typically shows osteolytic lesions, sharp sclerosis at the edges, and osteomyelitis at the periphery.

head CT

Plain scans are usually round or lobular cystic low-density masses with CT values lower than the cerebrospinal fluid. The tumor may be divided and calcification can be seen on the cyst wall. The border is clear and sharp, and there is no peritumoral edema. May be accompanied by obstructive hydrocephalus. On the enhanced image, there is no enhancement, and a few can see the cyst wall enhancement.

MRICranial MRI

The T1 weighted image shows a low signal, and the T2 weighted image shows a high signal. The signal intensity is uneven and grows lazily. The squamous extension is often along the adjacent subarachnoid space, and the occupying effect is usually light. Peritumoral edema is not obvious. Often the enhancement is not obvious during enhanced scans. MRI is better than CT for diagnosing and finding epidermoid cysts in the posterior cranial fossa, especially epidermoid cysts near the brainstem. Can show its space effect, tumor range, vascular displacement and so on.

The gold standard for diagnosis is still the result of pathological examination. ^[1]

Differential diagnosis of cholesteatoma

Epidermoid cysts should be distinguished from auditory neuromas and meningiomas when they are located in the cerebellar pontine angle. The latter two are more common in young people. Acoustic neuromas often develop onset of tinnitus and hearing loss, while meningiomas have less hearing impairment than auditory neuromas. Symptoms of cerebellar pontine syndrome and increased intracranial pressure are heavier than the disease. Cerebrospinal fluid protein generally increases.

Those located in the middle cranial fossa need to be distinguished from trigeminal schwannomas and meningiomas. The trigeminal schwannomas usually show enlarged oval holes in the skull base, and meningiomas usually have bone destruction or hyperplasia of the skull base. The clinical features and imaging findings were distinguished from other tumors at the corresponding site.

Cholesteroma emergency measures

Tumor strokes or spontaneous ruptures of contents are extremely rare, and patients' emergencies often result from hydrocephalus. under emergency. Consider ventricular puncture and drainage in advance, and resect the tumor in two stages when the situation improves. ^[2]

Cholesteatoma treatment

Cholelipoma is usually removed by surgery. Epidermal-like cysts in the posterior cranial fossa, especially those at the base of the posterior cranial fossa and the fourth ventricle, can take the midline suboccipital approach; those in the midbrain can access the subcranial superior cerebellum; those in the saddle area can take the wing point approach; the midline crosses the skull Dumbbells in the middle fossa and pontine cerebellar horns can be taken after one side of the mastoid approach.

If the tumor is small without intracranial expansion or infection, it will only slightly adhere to the surrounding structures, especially the epidermoid cysts in the fourth ventricle. However, it is difficult to achieve a histopathological complete resection of cholesteatoma in a large number of parts, and there is often a small amount of residual capsule, and sometimes there is an enhanced signal after magnetic resonance imaging.

The cyst wall of the tumor is germinal tissue, and the non-adhesive cyst wall should be removed as widely as possible. In order to prevent the tumor cells from spreading with the cerebrospinal fluid, a cotton sliver around the tumor can be protected during the operation. After carefully removing the contents of the cyst, pay attention to repeatedly flushing the surgical area to prevent postoperative aseptic meningitis.

For cholesteatomas in skull lamellae, only a few malignant changes have been reported, and resections are often performed for larger, faster-growing or tender tender cholesteatomas.

The prevention and management of postoperative complications of epidermoid cysts is the key to reducing the mortality and disability of this disease:

Common postoperative complications include:

Aseptic meningitis and ventriculitis: The most common is that the tumor contents enter the subarachnoid space or ventricle to stimulate brain tissue. The incidence is 10-40%. Most patients occur within 1-2 weeks after surgery. Early surgery and microsurgery for complete tumor resection is a fundamental measure to prevent this complication. Once it occurs, large doses of hormones and antibiotics can be used, and continuous drainage of cerebrospinal fluid can be performed with lumbar puncture or lumbar puncture tube. Most returned to normal within 1-4 weeks after the above treatment.

Hydrocephalus: Mainly due to recurrent meningitis or ventriculitis, symptomatic treatment can be taken, and shunt surgery can be considered after inflammation control.

(3) Chronic granulomatous arachnoiditis: As the contents of the sac are repeatedly discharged into the subarachnoid space, stimulating the formation of chronic granulomas in the arachnoid, large doses of hormones and symptomatic treatment can be given.

Secondary neurological dysfunction: The contents of the sac overflow, causing fibrosis around the nerves of the brain, and neurological dysfunction caused by compression.

Malignant transformation: It is relatively rare and becomes squamous epithelial cancer. Cancer can occur after repeated surgery and repeated recurrence, especially the epidermoid cyst of the pontine cerebellum. When the epidermoid cyst is surgically removed and the intended purpose is not achieved or the condition deteriorates rapidly, malignant changes should be considered. It can be widely seeded with cerebrospinal fluid. ^[3]

Prognosis of cholesteatoma

Because the tumor is a benign tumor, the postoperative recovery is generally good. If a major resection is reached, the recurrence is usually late, which can be extended to years or even decades. There are reports of long-term follow-up after surgery, which can reach 92% of patients who have survived for more than 20 years, and the postoperative mortality rate is 2-11%. The main cause of death is intracranial infection. Recent data from several groups of microsurgery indicate that its surgical mortality has fallen below 1%.

Because of the non-renewable nature of the nervous system, the purpose of cholecystectomy surgery is to prevent further neurological damage. The surgery may not be able to recover the existing neurological deficit.

Cholelipoma prevention

For intracranial cholesteatoma, there are no clear recommendations for prevention. For patients who have undergone surgery and pathologically confirmed, regular imaging review is needed to detect early tumor recurrence.