Meningioma

Introduction to meningioma Meningiomas are very common, accounting for 15.31% of intracranial tumors, second only to glioma. There are more adults, fewer elderly and children, and fewer infants and young children. Women are slightly more than men. It is a benign tumor that occurs in meningeal cells and is a very important tumor in the eyelids. Because of its high incidence, severe damage to vision, a wide range of violations, easy to spread to the bone canal, bone fissures and bone wall, often recurrence after surgery, and even cause death, and by ophthalmologists and neurologists It is worth noting that some tumors are difficult to determine their original location. basic knowledge The proportion of illness: 0.015% Susceptible people: no special people Mode of infection: non-infectious Complications: neurofibromatosis, hearing impairment, olfactory disorders

Cause of meningioma

Causes:

The etiology of this disease is still unclear, and its occurrence may be related to certain internal environmental changes and genetic variation, not caused by a single factor, and may be related to craniocerebral trauma, radiation exposure, viral infection, and bilateral auditory neuroma. The common feature of the factors is that they may cause cell chromosomal mutation, or the rate of cell division is increased. It is generally believed that the cell division of arachnoid cells is very slow, and the above factors accelerate the rate of cell division, which may be important in the early stage of cell degeneration. Stages, meningeal tumors include meningeal endothelial cell tumors, mesenchymal non-meningeal endothelial tumors, primary melanocyte lesions and tumors of unknown origin.

Physical factors (25%):

Some meningiomas are closely related to the site of injury and scarring, but a large number of investigations have not supported the evidence. The data indicate that radiation can induce cancer of the skin, lips, tongue, and esophagus. After several years of brain tumor radiotherapy, tumors of other nature occur in the irradiated area. Animal experiments have found that radiation can change between tissues (cancer). The mechanism is that radiation causes mutations in the oncogene of intracranial fibroblasts or meningeal endothelial cells, causing cancer of the cells.

Chemical factors (15%):

Animal experiments have confirmed that a variety of chemicals can induce brain tumors (various gliomas, meningiomas, sarcomas, epithelial cancers, pituitary adenomas, etc.), common steroids such as methylcholanthrene, diphenylguanidine, benzene And the ratio of N-nitrous acid compounds, such as nitrosopiperidine, dinitrosopiperazine, methyl nitrosourea, and the like.

Biological factors (15%):

Experiments have confirmed that viruses (such as adenovirus, monkey vacuolating virus (SV40), sarcoma virus, etc.) can induce intracranial tumors in poultry and vertebrates. The insertion of the virus into the chromosome of the cell changes the characteristics of the chromosomal gene and changes the original proliferation characteristics of the cell.

Congenital and genetic factors (25%):

During embryonic development, some cells or tissues can stop growing and remain in the brain. They have the potential to differentiate and can develop into brain tumors. Commonly there are craniopharyngioma, chordoma, teratoma, epithelioid and dermoid cysts.

Pathogenesis:

Meningiomas belong to meningeal endothelial cell tumors, which may be derived from arachnoid villi or embryonic remnants, including 11 types, meningeal endothelial type, fibrous type, mixed type, sand granule type, vascular type, microcapsule type, secretory type, transparent cell type, Chordal-like, lymphoplasmic cell type, metaplastic type, the most common of which is the meningeal endothelial type, accounting for 53.5% of meningiomas.

Meningiomas are spherical and flat. They are more common in spherical shape, complete in surface or nodular, colored film, often with a "umbilical" connected to the dura mater; flat thickness often does not exceed 1 cm, widely distributed on the dura mater. It is more common in the bottom of the skull. The meningioma is rich in blood vessels. It is mainly supplied by the external neck and the intracervical (or vertebral basal) arteries. The tumor section is dark red, and there may be a milky yellow area with flaky lipid deposition. Sometimes see calcified grit, a few have cystic changes, meningioma tissue morphology has a variety of performance, but each type has a basic structure of meningioma, containing meningeal endothelial cell components, cell arrangement often retain arachnoid villi and arachnoid Some of the characteristics of the particles are swirling or concentric. The middle part of these concentric circles is prone to hyaline degeneration or calcification. The fibrous tissue, vascular tissue, fat, bone or cartilage and melanin are visible in the tumor tissue. The tumor malignancy is grade I. .

Meningioma prevention

1. Avoid harmful substances (promoting factors) that can help avoid or minimize exposure to harmful substances.

Some related factors of tumorigenesis are prevented before onset. Many cancers are preventable before they are formed. A US report in 1988 compared the international malignant tumors in detail, suggesting that many of the known malignancies are preventable in principle, that is, about 80% of malignant tumors can be changed through simple lifestyles. prevention. Continuing with the retrospective, a study by Dr. Higginson in 1969 concluded that 90% of malignant tumors are caused by environmental factors. Environmental factors and lifestyle refer to the air that breathes, the water that is drunk, the food that is selected for production, the habits of activities, and social relationships.

2, improve the body's immunity against tumors can help improve and strengthen the body's immune system and cancer.

The focus of cancer prevention and treatment should focus on and improve those factors that are closely related to life, such as smoking cessation, proper diet, regular exercise, and weight loss. Anyone who follows these simple and reasonable lifestyle knowledge can reduce cancer. Opportunity.

The most important thing to improve the function of the immune system is: diet, exercise and control troubles, healthy lifestyle choices can help stay away from cancer. Maintaining a good emotional state and proper physical exercise can keep your body's immune system at its best, and it is also good for preventing tumors and preventing other diseases. In addition, studies have shown that appropriate activities not only enhance the body's immune system, but also reduce the incidence of colon cancer by increasing the peristalsis of the human intestinal system. Here I mainly understand some of the problems of diet in preventing tumorigenesis.

Human epidemiology and animal studies have shown that vitamin A plays an important role in reducing the risk of cancer. Vitamin A supports normal mucosa and vision, and it directly or indirectly participates in most of the body's tissue functions. Vitamin A is found in animal tissues such as liver, whole egg and whole milk. Plants are in the form of beta-carotene and carotenoids, which can be converted into vitamin A in the human body. Excessive intake of vitamin A can cause adverse reactions in the body, while -carotene and carotenoids do not. The low vitamin A content in the blood increases the risk of malignant tumors. Studies have shown that those with low levels of vitamin A in the blood People who enter are more likely to develop lung cancer, and those who have low levels of vitamin A in their bloodstream may have an increased risk of lung cancer. Vitamin A and its mixture can help remove free radicals in the body (free radicals can cause damage to genetic material), and secondly stimulate the immune system and help differentiate cells in the body to develop into ordered tissues (and tumors are characterized by disorder) . Some theories suggest that vitamin A can help cells that have been previously mutated by carcinogens to reverse and become normal growing cells.

In addition, some studies suggest that supplementation with -carotene alone does not reduce the risk of cancer, but rather increases the incidence of lung cancer. However, when -carotene binds to vitamins C, E and other antitoxins, its protective effect. It shows up. The reason is that when it consumes itself, it can also increase free radicals in the body. In addition, there are interactions between different vitamins. Both human and mouse studies have shown that the use of -carotene can reduce 40% of vitamin E levels in the body, which is safer. The strategy is to eat different foods to maintain a balanced vitamin to protect against cancer, as some protective factors have not yet been discovered.

Vitamins C and E are another anti-tumor substance that can prevent the harm of carcinogens such as nitrosamines in food. Vitamin C protects sperm from genetic damage and reduces the risk of leukemia, kidney cancer and brain tumors in their offspring. . Vitamin E can reduce the risk of skin cancer. Vitamin E has the same anti-tumor effect as vitamin C. It is an anti-toxin and a scavenger that scavenges free radicals. The combination of vitamin A and CE produces a protective effect against the toxins that is better than a single application.

Research on phytochemistry has attracted widespread attention. Phytochemistry is a chemical found in plants, including vitamins and other substances found in plants. The chemical constituents of thousands of plants have been found, many of which have anticancer effects. The protective mechanisms of these chemicals not only reduce the activity of carcinogens but also enhance the body's immunity against carcinogens. Most plants provide more antioxidant activity than plants. The protective effect of vitamin A, C, and E alone. For example, a cup of cabbage contains only 50 mg of vitamin C and 13 U of vitamin E, but its antioxidant activity is equivalent to the antioxidant activity of 800 mg of vitamin C and 1100 U of vitamin E. It can be inferred that the antioxidant effect in fruits and vegetables is far more effective than the known vitamins. Undoubtedly natural plant products will help future cancer prevention work.

Meningioma complications Complications neurofibromatosis hearing impairment olfactory disorders

This tumor may be associated with neurofibromatosis, complications such as vision, visual field, olfactory or hearing impairment and limb dyskinesia, vision loss, and the primary site of the tumor, most of which occur early and severe in the symptoms of the optic canal. Early optic disc edema, after a long-term process, developed into a secondary optic atrophy tubular meningioma. Early visual field contraction occurs in the apex of the apex, and dark spots in the visual field may appear.

Meningioma Symptoms Common Symptoms Ocular Highlights Intracranial Pressure Increased Posterior Optic Neuritis Hydrocephalus Secondary Optic Nerve Atrophy Forehead Masses Sella Bulbs

Meningioma mostly occurs in middle-aged women. The meningioma originating in the sputum is younger than the intracranial. The younger the age of onset, the faster the tumor develops, the more chances of multiple tumors, and the higher the recurrence rate after surgery. .

Meningioma originating in the sputum, due to different sites, clinical manifestations are different, even in the tumor of the optic nerve sheath, the original in the tube or intraorbital symptoms are not the same, the tumor that occurs in the optic nerve sheath, there are often two A form of growth, a form of tumor cell hyperplasia, and invasion of the sheath gap, pia mater and dura mater, but the dura mater is not pierced, the surface remains intact, the tumor develops in both the eyeball and the intracranial direction, and the shape is tubular. Rough, another form is the early perforation of the tumor through the dura mater, that is, along the longitudinal axis of the optic nerve, growing around the optic nerve or to one side, the shape is fusiform or massive, the tumor is increasing, restricted by the wall, then formed A conical lumps with a uniform cavity, which occur in the periosteal tumor, grow along the periosteum, do not affect the optic nerve early, and have symptoms and signs similar to the surrounding interstitial tumor.

The most common and early signs of meningioma in the orbit are eyeballs, which are present in more than 95% of cases, especially in the early stage of perforating the meninges to the optic nerve or around the optic nerve and tumors that originate outside the optic nerve sheath. Eyeball protrusion is the earliest cause of the patient's attention. The direction of the eyeball is generally developed along the axial direction of the eye. The tumor that originates from the periosteum of the sphenoid wing mainly tends to make the eyeball inward and downward, and the degree of eyeball protrusion varies from person to person. The difference can be very large. The tumor originates from the optic nerve sheath in the optic canal, or develops along the sheath. The degree of eyeball is low, and even the intracranial has spread. The protrusion of the two eyes is only 2 to 3 mm. The tumor occurs in the sputum and is massive. The growth of the eyeball is prominent, the difference between the two sides can reach more than 20mm, and the eyeball is out of the cleft.

Severe vision loss is also one of the early symptoms. In newly diagnosed patients, the visual acuity is less than 0.1%, and the loss of vision is related to the primary site of the tumor. In the optic canal, vision loss and visual field loss are often the only ones in the early stage. Symptoms, only a small number of patients with headache, long-term without eyeball protrusion, often misdiagnosed as posterior optic neuritis, along the development of optic nerve sheath, tubular meningioma, compression optic nerve fibers, atrophy, vision The loss is also earlier, and the eyeball is not obvious. Only those meningiomas that pierce the optic nerve dura early, develop to one side, or originate outside the optic nerve sheath, have vision loss in the late stage, and early visual field contraction of the tubular meningioma. , occurs in the tip of the sputum, can appear dark spots in the field of vision.

Fundus changes are also a common and important sign of optic nerve sheath meningiomas. Early optic disc edema, after a long-term process, develops secondary optic atrophy, unclear optic disc boundaries, grayish and grayish smudges, and mild upward bulge, the surface of the optic disc often appears The optic nerve ciliary vein, the posterior pole flat bulge and the choroid-retina fold, and the anterior bulge after optic atrophy, is the result of long-term edema, glial cell proliferation, or tumor cell invasion.

Meningioma texture is hard, occurs in the optic nerve sheath can hinder the movement of the optic nerve and cause eye movement disorder, affecting venous return, causing eyelid and conjunctival edema, middle-aged female eyelid chronic edema, inflammatory pseudotumor, thyroid-related eye disease and malignant In addition to tumors, meningioma should also be considered. In the late stage of the disease, or in the tumor of the periosteum of the anterior temporal sac, it can also be treated with hard mass. The symptoms of meningiomas are more significant during pregnancy and develop faster.

The diagnosis of tumors also depends on the auxiliary diagnostic examination to diagnose meningioma. The examinations with important reference value include skull radiograph, CT scan and cerebral angiography, which can not only achieve localization, but also understand tumor size and qualitative.

1. Skull plain film: intracranial meningioma requires routine imaging of skull bone, about 75% of cases can show signs of intracranial tumors on plain films, and 30% to 60% of cases can make meninges according to the signs of plain films. The diagnosis of the tumor, the sign of the X-ray skull flat film, part of the intracranial tumor, indirect signs of increased intracranial pressure, such as the erosion and enlargement of the saddle bone, the cerebral gyrus and the pineal calcification plaque shift, a few In the case of cranial suture separation, the other part is the direct cause of meningioma, including local bone hyperplasia and destruction of the tumor, the widening and increase of meningeal sulcus caused by increased tumor blood supply, tumor calcification, local bone thinning, etc. These points are often a reliable basis for diagnosis of meningioma.

2. CT scan: In the diagnosis of meningioma, CT scan has replaced isotope brain scan, gas brain and ventriculography, meningioma is mostly substantial and rich in blood, most suitable for CT examination, its accuracy can reach the discovery 1cm size meningioma, meningioma has special signs on CT scan images, showing a limited contrast-enhanced contrast-enhanced image in the skull, which can also have bone hyperplasia, and density decreases around the tumor. Brain edema zone, corresponding brain shift, and signs of hydrocephalus caused by cerebrospinal fluid circulation obstruction.

3. Cerebral angiography: For some meningioma, cerebral angiography is still necessary, especially deep meningioma, its blood supply is multi-channel, only through cerebral angiography, can understand the source of tumor supply, and The degree of tumor blood supply and the distribution of adjacent blood vessels are of great value in the development of surgical plans, surgical approaches and surgical methods. If selective external carotid artery, internal carotid artery and vertebral artery angiography are available, Digital subtraction angiography, the signs of vascular changes are clearer and clearer.

In addition, lumbar puncture can reflect the increase of intracranial pressure and the increase of cerebrospinal fluid protein content, and it still has certain reference significance in diagnosis and differential diagnosis.

The diagnostic features of optic nerve sheath meningioma are:

1 clinical quadruple sign, more common in adult women, unilateral eyeballs;

2 loss of vision;

3 characteristic optic disc edema and atrophy;

4 The ciliary vein of the optic disc, CT and MRI showed different degrees of thickening of the optic nerve, especially when the tumor spread through the optic canal to the skull.

Meningioma examination

General laboratory tests are not specific.

Ultrasonic exploration

Tumors are more irregular in A and B than gliomas, and the echo is uneven. The anterior horn of the optic nerve becomes dull, and there are often strong echo spots or calcifications. The sound attenuation is obvious. Other secondary changes such as optic disc edema Ultrasound showed good pressure on the wall of the eyeball.

Sometimes the mildly thickened ultrasound of the optic nerve may be difficult to display. It is necessary to compare the two sides. The B-ultrasound shows that the optic nerve is prolonged and the boundary of the optic nerve is unclear. Because the tumor sound attenuation is obvious, the thickened full-length optic nerve cannot be displayed. Tumors can only show the oblique section of the tumor. If there is more calcification in the tumor, only the front boundary of the lesion may be displayed.

2. CT scan

CT is very valuable for the diagnosis of optic nerve tumors, especially for calcification in tumors. The nature of CT recognition lesions is mainly based on the shape and density of optic nerve thickening. Therefore, whether the intra-orbital mass is the thickening of the optic nerve itself is to identify optic nerve tumors and balls. After the other tumors, due to the volume effect of CT or the optic nerve and tumor density values, the horizontal axis CT sometimes cannot distinguish between the thickening of the optic nerve itself or the tumor on the side of the optic nerve. At this time, coronary CT or MRI may be better. Identification method.

Thin-slice CT scan can better show optic nerve sheath meningiomas. Because the tumor has no obvious capsule, the tumor axis is invisible in the horizontal axis or coronary CT, and the invasive growth is increased. CT diagnosis of optic nerve sheath meningiomas is mainly based on the shape of the lesion. And location, the tumor can be tubular, massive, fusiform, irregular and eccentric, in addition to enhanced CT display of "vehicle signs" (enhanced between tubular high-density tumors and unenhanced optic nerves) Density difference, but if the apical tumor is lumpy, it can also show that the low-density linear optic nerve is surrounded by high-density tumors.) and intratumoral calcification is a typical CT sign of optic nerve sheath meningiomas. Seen in other optic nerve sheath lesions such as inflammatory pseudotumor around the optic nerve, optic nerve inflammation and other optic nerve sheath lesions, the optic nerve is obvious tubular thickening when the diagnosis is easy, but only for the tip of the lumps when the CT is not easy and other tips Tumor identification.

The cause of peripheral edema caused by meningiomas is not well understood. It may be related to the destruction of the normal blood-brain barrier in meningeal cancer patients and the secretion of certain substances in meningioma tissues. Recently, some people believe that edema and tumors around the meningioma. Prostaglandin levels or tumor progesterone receptor release are associated.

CT can provide good humerus and parasagittal anatomy, which can show intratumoral calcification and meningioma combined with bone hyperplasia. Intracranial and intraorbital meningioma enhanced CT showed tumor enhancement, moderately sized meningioma intracranial Spread, enhanced CT can also show, but flat or small tumors spread to the brain, especially tumors <5mm in diameter may require MRI imaging, CT has limited effect, although CT can show local bone hyperplasia caused by tumor ( Optic nerve sheath meningioma is rare), intratumoral calcification, but poor display of optic canal and / or intracranial tumors, CT defects are ionizing radiation, can not directly multi-angle imaging, partial volume effect and bone artifacts, etc. It affects the display of intracranial and optic canal meningiomas.

3.MRI

Because of the better soft tissue display, it is very important to find and estimate optic nerve sheath tumors. Intracranial meningioma is similar to intracranial meningioma with characteristic MRI signals. Most tumors have equal or low signal in TlWI compared with cerebral cortex. It is easy to identify. Tumor signals on T2WI are related to histopathological findings. Most of them are medium signals. For example, calcification in tumors is characterized by low signal. Smaller meningioma may not be found in non-enhanced MRI.

Enhanced Gd-DTPA can show a high degree of enhancement in tumors. Enhanced MRI + fat suppression is the best way to show the spread of meningioma, especially intracranial or optic canal. For other optic neuropathy, smaller or flat meningioma. Intracranial spread can only be shown by enhanced MRI+fat inhibition imaging. Lindblom reported enhanced MRI examination of 13 cases of optic nerve sheath meningioma, 11 of which found intracranial spread, and the transverse axis and coronal position of the enhanced MRI scan showed better. The shape is often poor due to the scan angle relationship.

The incidence of intracranial spread of such tumors is high. Once the tumor spreads to the tip of the iliac crest, whether the optic nerve is tubular thickening or the apical tip is filled with massive mass, the possibility of tumor spreading into the skull should be suspected.

Enhanced MRI+fat inhibition is the best method for showing optic nerve sheath meningiomas, especially suspected intracranial spread. It should be used as a routine examination of preoperative and postoperative optic nerve sheath meningioma to detect intracranial lesions early.

Bilateral optic nerve sheath meningiomas are not uncommon in clinical practice and should cause clinical attention. Bilateral meningiomas can be intracranially spread with serious consequences.

4. Pathological examination

Meningioma specimens differ in their location and growth pattern. They occur in the optic nerve sheath in a flat or massive form. The former grows along the meninges and the optic nerves are thickened, and the dura mater of the optic nerve sheath is not worn. It is characterized by uniform or irregular thickening of the optic nerve, smooth surface, reddish color, fusiform or massive enlargement at the tip of the sputum, indicating that the optic canal has resistance to tumor spread, optic nerve section, optic nerve sheath gray thickening, optic nerve Substantially thinned, the tumor that pierces the dura mater early, grows around the optic nerve or toward the optic nerve, is spherical, lobulated, irregular, conical or fusiform, optic nerve in the axial or eccentric, piercing the optic nerve dura mater The tumor lacks the envelope, the surface is fine-grained, grayish white, hard texture, and less blood vessels. This point is different from meningioma secondary to the brain. The latter is rich in blood supply and has more bleeding during surgery. It occurs in the periosteum of the iliac crest. Meningiomas, mostly flat or spherical growth, periosteal invasion, hyperplasia of the local bone wall, rough, spongy, tumors formed by ocular ectopic cells Shaped growth, lack of off-white envelope.

The histological classification of intraorbital meningioma is roughly the same as that occurring in the intracranial, and the early classification is complex. It has been divided into nine categories. In recent years, it has been reduced to type 3, ie, meningeal epithelium (also called fit type), sand type (transition). Type) and fibroblast type (also known as fiber type), sand type is a variant of the epithelial type, and thus can also be divided into two types. Wilson in his review of anterior approach meningioma, proposed to divide meningioma into type 5 More suitable, namely meningeal epithelial type, sand type, fibroblast type, vascular type and sarcoma type, epithelial meningioma is the most common, accounting for 50% to 75% of intraorbital meningiomas. Microscopically, the tumor cells are rich in cytoplasm. Flaky, nested or vortex (Figure 7), the cell boundary is unclear, in the form of syncytial cells, the cell body is large, the polygon, the nucleus is also large, round, located in the center of the cell, there are 2 to 3 nucleoli The chromatin is small and fine, and the interstitial and blood vessels of the tumor cells are less than those of the same type in the skull. The sand-type meningioma is also called transitional or mixed type, between the epithelial type and the fibrous type, and there are two kinds of tumor cells. The cell body is fusiform and polygonal, with an elliptical nucleus and a cell vortex Arranged, with small blood vessels in the center, degeneration of the wall, and deposition of calcium, forming a concentric layer of sand granules (Fig. 8). The fibroblastic tumor cells are long fusiform, nucleus-like, braided, wavy. Or incomplete spiral arrangement, the vascular sinus cells with polygonal meningeal cells are vascular meningioma, and the sarcoma type is malignant meningioma.

The tissue of meningiomas sometimes presents with cellular metaplasia, such as cartilage, ossification, mucous degeneration, steatosis, etc. When histological diagnosis is difficult, immunohistochemical techniques are helpful, and cytoplasmic proteins in meningioma cells (vimentin), S-100 protein and epithelial membrane glycogen staining.

Diagnosis and diagnosis of meningioma

Tumors that need to be differentiated from meningiomas vary from site to site. On-screen meningioma should be differentiated from gliomas and metastases. Mantle tumors in the sellar region should be differentiated from pituitary tumors. The cerebellopontine meningioma should be differentiated from acoustic neuroma.

In the differential diagnosis of glioma, the age of onset and the shape of optic nerve thickening are better identified. It is easy to be confused with the irregular shape of the tumor inside the muscle cone. Because the density is close, it is difficult to identify on CT, so it often needs to rely on Other clinical methods such as ultrasound, clinically, can also see inflammatory pseudotumor around the optic nerve, symptoms and optic nerve sheath meningiomas are similar, imaging studies have similarities, at this time the symptoms and signs of clinical inflammation is very helpful in differential diagnosis However, bilateral optic nerve sheath meningioma can be seen clinically. It should be noted in differential diagnosis. According to statistics, bilateral optic nerve sheath meningiomas account for 9% to 23% of orbital meningioma.

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