astrocytoma
Introduction
Introduction to astrocytoma Astrocytic tumors are tumors composed of astrocytes and are the most common neuroepithelial tumors. It is divided into I to IV. Grade I, in adults, mostly infiltrate and grow in the white matter of the brain, divided into two types: pure pulp type and fiber type. Class II is a poorly differentiated astrocytoma, or astrocytoma. The progression of these two types of disease is slower. Astrocytoma grade III to IV, glioblastoma multiforme, is highly malignant and is common after middle age. Astrocytoma can occur in any part of the central nervous system. Generally, adults are more common in the brain, and children are more common in the lower part of the brain. There are reports on the screen accounted for 3/4, and the curtain accounted for l/4. Occurring on the screen is more common in the frontal and temporal lobes, followed by the parietal lobe, occipital lobe is less common, tumors can involve more than two lobes. It can also be seen in the optic nerve, the thalamus and the third ventricle. The under-the-scenes are located in the cerebellar hemisphere and the fourth ventricle, as well as in the cerebellar vermis and brainstem. basic knowledge The proportion of illness: 0.001% Susceptible people: no specific population Mode of infection: non-infectious Complications: intracranial hemorrhage
Cause
Astrocytoma etiology
Neuroepithelial lesions (25%)
Hairy cell astrocytoma grows slowly and is derived from neuroepithelial neoplasia. Tumors occur in the white matter of the midline structure and the cerebellar hemisphere. The most common occurrence in the funnel is sometimes called funneloma. It occurs in the optic nerve called optic glioma, which occurs in the anterior, hypothalamus and brainstem. The tumor boundary is unclear, more substantial, and blood supply is abundant.
Genetic factors (20%)
Clinical statistics show that there is a family with astrocytoma, and the incidence of family members is several times higher than that without family history. Therefore, genetic factors are an important factor in the disease.
Pathogenesis
Astrocytic tumors can occur in any part of the central nervous system. Generally, adulthood is more common in the cerebral hemisphere and thalamus. In the bottom section, children are more common in the underside of the screen. It is reported that the screen is 3/4, and the curtain is 1/4, which occurs in the curtain. The upper part is more common in the frontal and temporal lobes, the parietal lobes are second, the occipital lobe is less common, the tumor can involve more than two lobes, and can also be seen in the optic nerve, the thalamus and the third ventricle; the under-the-scenes are mostly located in the cerebellar hemisphere and The fourth ventricle can also be seen in the cerebellum and the brainstem.
1. Astrocytoma: The tumor is mainly located in the white matter, showing invasive growth, and the solid has no obvious boundary. Most of them are not limited to one brain leaf. The outward growth can invade the cortex, and the inward can destroy the deep structure. The corpus callosum crosses the midline and invades the contralateral cerebral hemisphere. The texture of the corpuscle is grayish red or grayish white. The texture is harder. About half of the tumors are partially cystic, the cystic fluid is yellowish and transparent, and the protein content is high. It is easy to self-coagate. For the Froin sign, the cystic tumor can be called "sac in the tumor", while the astrocytoma in the cerebellum is often a large sac, with tumor nodules on the wall, fibrous connective tissue and The glial fiber is composed, so only the tumor nodules can be removed to achieve the purpose of radical treatment. The tumor is called "tumor in the sac", and a few cerebellar astrocytomas are substantial, invasive growth, no obvious At the border, the prognosis is worse than that of the cystic.
According to the histological features of the tumor, astrocytoma can be divided into three subtypes: fibrosis, protoplasm and obesity:
(1) Fibrous type: the most common, can be found in any part of the central nervous system and patients of all age groups, more common in the adult hemisphere; in children and adolescents more common in the cerebellum, brain stem and thalamus, slow growth, texture Hard and tough, sometimes as rubber, diffuse tumor section is white, not easy to distinguish from surrounding brain tissue, adjacent cortex can be infiltrated by tumor, dark gray color, blurred boundary with white matter, cysts can be formed in the center of the tumor, the number of sizes is uncertain, focal Type tumor boundary smoothing, mainly found in the cerebellum, often with large cyst formation, so that the tumor is biased to one side, stained with hematoxylin-eosin (HE) under light microscope, the prominent feature is that the tumor is rich in glial fibers, tumor The cells resemble fibrous astrocytes in the white matter. The cells are small, abundant, oval, tumor cells differentiate well, the nuclear-to-plasma ratio is close to normal, no nuclear division and abnormal shape, most can not see the cytoplasm, only showing a round shape Or oval nucleus, the size is uniform, the distribution is also uniform, visible criss-cross, uneven thickness, varying lengths of blue glial fibers, less intravascular blood vessels, Small calcification or small cystic cavity, small brain tissue reaction, light edema, no inflammatory cell infiltration, mostly located in the deep white matter, under the electron microscope, there are a lot of gelatinous filaments in the cytoplasm and protrusion of the perinuclear nucleus. Curl-like arrangement, organelles are sparse, and often located at the edge of the perinuclear cytoplasm due to glia filaments, mainly composed of astrocytoma, often mixed with protoplasmic astrocytoma.
(2) pure pulp type: the least common type, soft texture, mainly found in the brain, mostly in the temporal lobe, the surface is superficial, mainly invading the cerebral cortex, so that the affected brain is widened, soft, flattened to Characteristics, the tumor is large, gray-red, the cut surface is translucent and uniform jelly-like, deep invading white matter, infiltrating growth in the brain, the boundary is unclear, often denatured, forming cysts, the size of the cyst, the number is uncertain, the surrounding is Tumor tissue, the morphology of tumor cells under light microscope has the characteristics of protoplasmic astrocytes, the morphology and distribution are consistent, the volume is large, the cytoplasm is full, the nucleus is round, the size is the same, often on one side, nuclear division is rare, interstitial Eosinophilic staining, like a spider web, no glial fibers without capsule, cystic changes, a few have hemorrhagic foci, electron microscopic nucleus and protrusions in the perinuclear nucleus and no or few colloidal filaments, organelles are more fibrous There are many astrocytomas, including microtubules, ribosomes, endoplasmic reticulum, mitochondria and membranous vesicles. The tumors are mainly protoplasmic astrocytes, often mixed with fibroblastic astrocytoma.
(3) Obese cell type: less common, occurs in the cerebral hemisphere, can also be seen in the transparent compartment, accounting for 5% to 10% of the adult cerebral hemisphere neuroepithelial tumor, accounting for 25% of astrocytoma, tumor Invasive growth, rapid growth, soft texture, often visible small cyst formation, visible obese cells under light microscopy, volume hypertrophy, spherical or polygonal, cytoplasm uniform and transparent, short and thick protrusions, small tumor cell On one side, the tumor cells are densely distributed, sometimes arranged around the blood vessels to form pseudo-Chrysanthemum-like, glial fibers are confined around the cell body, electron microscopic cytoplasmic hypertrophy, rare peripheral cytoplasmic processes, cytoplasm is filled with short The mesh woven by the colloidal tow, the organelles are scattered between the gelatinous filaments, far less than the colloidal filaments, but sometimes there are more mitochondria.
2. anaplastic or malignant astrocytoma: mainly found in the brain, the tumor is large, sometimes invading several lobes or crossing the midline to invade the contralateral cerebral hemisphere, the tumor tissue is grayish red, the texture is soft, in the brain Invasive growth, with a certain boundary with the surrounding brain tissue, tumor cells can infiltrate into the cortex, forming a "satellite phenomenon" around the circumference of the neurons, cystic changes and small focal hemorrhagic necrosis, different from astrocytoma, Tumor cells are abundant, diverse in morphology, nucleus is pleomorphic, mitotic figures are more common, nuclear-to-nuclear ratio is increased, mononuclear or multinucleated giant cells, fibrous, protoplasmic and obese cell astrocytoma can be seen in several After the year, it became malignant. Glial fibers were less common than astrocytoma. 9% of the tumors showed a small amount of calcification. Sometimes there was obvious fibrous connective tissue in the tumor, forming a so-called "anaplastic glioma". Necrosis or vascular proliferation, which can be differentiated from pleomorphic glioblastoma. Because of the different degrees of cell differentiation in various parts of the tumor, the shape of the above tumor appears in a well-differentiated place. The diagnosis of this tumor should be concluded after comprehensive histological observation. When only some tumors, especially biopsy tissues, are observed, the diagnosis may be inaccurate, and attention should be paid to the marginal tissue of glioblastoma.
3. Hairy cell astrocytoma: Hair cell astrocytoma grows slowly and is derived from neuroepithelial neoplasia. The tumor occurs in the white matter of the midline structure and the cerebellar hemisphere, which is most typical in the funnel. Sometimes called a funnel tumor; occurs in the optic nerve called optic glioma, occurs in the anterior visual pathway, the tumor boundary of the hypothalamus and brainstem is unclear, more substantial, blood supply is abundant, and the cerebellar and brain tumors are clear. 90% have cystic changes, and the wall often has a hard gray-red nodule. Unlike cystic astrocytoma, it has no tumor cells away from the nodular wall, and a few hairy cell astrocytomas can The nerve axis is spread.
Microscopic hairy cell astrocytoma consists of well-differentiated ciliated cells in parallel and densely packed mucus containing microcapsules and granules. It is monopolar or bipolar, rich in neurofibrils, and tumor cells. The two poles continue, so the histological morphology of the tumor is braided or reticular, or it can be arranged in parallel in a wave shape. The tumor cells have hair-like polar protrusions, and the nucleus is rod-shaped, fusiform or oval, due to tumor cells. Good differentiation, it is difficult to see mitotic figures, containing bundles of nerve fibers and thick and long Rosenthal fibers, a small amount of astrocytes and oligodendrocytes in the mucus, anterior tumor and astrocytosis Similarly, it is expansive growth, destroying the internal structure of the optic nerve, demyelination of the optic nerve, loss of axons, and more mucopolysaccharide in the tumor. The hypothalamic tumor cells are not strictly parallel and typical bipolar extension. Long features, less microcapsules, and prone to malignant changes.
Electron microscopy consists almost entirely of fibrillar astrocytes. The perinuclear cytoplasm and processes are filled with tight gelatinous filaments. Rosenthal fibers are the center of extremely dense glia tow, irregular and unstructured dense electronic matter. Large-scale case statistics Hair cell astrocytoma is uncommon, accounting for 4.0% to 5.0% of intracranial gliomas, accounting for 7% to 25% of various types of astrocytomas in the adult group, but younger groups (20 Below age) 76% to 85%.
Prevention
Astrocytoma prevention
First, improve bad habits, including smoking, partial eclipse, and fullness.
Second, pay attention to the environment.
Third, a health checkup is conducted every year.
Fourth, to exercise and maintain physical and mental health, many diseases are related to immune function.
Complication
Astrocytoma complications Complications intracranial hemorrhage cerebral edema
If surgery is performed, the following complications may occur:
1. Intracranial hemorrhage or hematoma: It is not related to intraoperative hemostasis. With the improvement of surgical techniques, this complication has been less frequent. The wound is carefully hemostasis and repeated flushing before closing the skull can reduce or avoid postoperative intracranial hemorrhage.
2. Brain edema and postoperative high intracranial pressure: decompressive drugs can be used to reduce intracranial pressure, glucocorticoids reduce brain edema.
3. Loss of nerve function: related to the important functional area and important structure of intraoperative injury, avoiding damage as much as possible during surgery, and symptomatic treatment after emergence.
Symptom
Astrocytoma Symptoms Common Symptoms Consciousness of Consciousness Loss of Visual Field Defects Oculomotor Paralysis Movement Disorders Hydrocephalus Diabetes Rejection Indifference Drowsiness Focal Symptoms
Astrocytoma grows slowly and has a long course of disease. It can be up to 2 years from the onset of symptoms to the time of treatment. Sometimes it can be up to 10 years. The clinical symptoms include general symptoms and local symptoms. The former depends mainly on the increase of intracranial pressure, while the latter depends on the increase. The location of the lesion and the pathological type and biological characteristics of the tumor.
General symptoms
The continuous growth of the tumor occupies the space inside the cranial cavity. The tumor obstructs the cerebrospinal fluid circulation pathway and causes hydrocephalus and/or cerebral edema in the brain. The cerebrospinal fluid reabsorption disorder can increase the intracranial pressure. The normal cranial volume is about 10% larger than the brain tissue. When the volume of brain tissue increases by 8% to 10%, there may be no symptoms of intracranial hypertension. When the intracranial lesions occupy more than 150 ml, the corresponding symptoms of intracranial hypertension may occur. Astrocytoma of the cerebral hemisphere. The onset is slow and the course of disease is long. Most of them have localized signs and symptoms caused by direct destruction of the tumor. Then there are symptoms of increased intracranial pressure. Cerebellar astrocytoma has an early cranial fluid circulation pathway. Symptoms of increased internal pressure, astrocytoma of the brainstem progress faster, shorter course, early brain damage and pyramidal tract signs, and symptoms of increased intracranial pressure are common in the late stage. Symptoms of increased intracranial pressure include Headache, vomiting, optic disc edema, visual field of vision change, epilepsy, diplopia, head enlargement (childhood) and changes in vital signs.
2. Clinical manifestations of tumors of different natures
(1) astrocytoma: slow growth, the course of disease is often several years, an average of 3.5 years, most patients are slowly progressive development, epilepsy is often the first symptom, 50% of patients with epilepsy, 75% have headache, 50% have psychomotor muscle weakness, vomiting and obvious disturbance of consciousness are 33% and 20%, respectively. Most patients with neurological examination have optic disc edema and cranial nerve disorders, accounting for 60%, and nearly half of the patients have limb muscle weakness. There are speech difficulties, feelings of difficulty, and visual field changes are also 20%.
(2) anaplastic astrocytoma: the course of disease is shorter than that of astrocytoma, with an average of 6 to 24 months. The main clinical symptoms of cerebral hemisphere lesions are headache (71%), mental symptoms (51%), and limb weakness (40%). ), vomiting (29%), speech difficulties (26%), visual acuity (23%) and lethargy (22%), seizures are rare, neurological examination can detect hemiplegia (59%), optic disc edema (47%), Cerebral nerve damage (46%), hemianopia (32%), partial sensation loss (32%), the onset of progressive aggravation, some may suddenly worsen, the early stage of the brain tumor can have increased intracranial pressure, there are Hemiplegia, neuropathic weakness, memory loss, confusion of consciousness and symptoms of epilepsy and endocrine disorders, anterior visual tumors develop rapidly, from unilateral vision to bilateral blindness no more than 2 months, often accompanied by headache, fever and urine In the late stage, the fundus of the fundus was swollen and the arteriovenous occlusion was observed.
(3) hairy cell astrocytoma: the general course of disease is long, the anterior approach tumor is located in the sacral area mainly for visual impairment with painless exophthalmos, there may be different types of hemianopia, strabismus and optic atrophy Tumors located in the optic chiasm are affected by bilateral visual acuity, optic disc edema, strabismus, optic atrophy and headache, hypothalamic tumors with endocrine disorders, diencephalic syndrome, Frölich syndrome and precocious puberty, diameter 2cm or more Tumors can cause hydrocephalus, brainstem tumors with tumor plane cross sputum as the main performance, brain type tumors can have epilepsy, increased intracranial pressure symptoms and focal symptoms, and cerebellar tumors are unstable and other ataxia which performed.
3. Clinical manifestations of tumors in different sites
(1) cerebral hemisphere astrocytoma: it may be solid, or there may be a large sac, a part of the wall is attached with a tumor parenchyma, about 60% of cerebral hemisphere astrocytoma has epilepsy, and the tumor is close to the brain surface. It is prone to occur, about one-third of patients can have epilepsy as the first symptom or main symptom, but after several years, intracranial pressure and focal symptoms appear. The type of seizure is related to the location of the tumor. The frontal lobe is mostly In the epileptic seizures, the central region and the parietal lobe are mostly focal episodes, and the temporal lobe tumors are manifested as psychomotor seizures. Extensive violations of frontal lobe tumors, especially in patients who invade the corpus callosum to the contralateral hemisphere, include significant mental disorders, including Slow response, distracted attention, emotional abnormalities, memory loss, decreased orientation and computational power, etc., when the occipital lobe involves the visual conduction pathway or visual center, there may be visual hallucinations, visual field defects, and often appear in the vicinity of the posterior central anterior gyrus. Different degrees of hemiplegia, the lower corner of the parietal lobe and the upper back of the rim may have miscalculation, loss of reading, misuse and naming disorder, in the dominant hemisphere movement or sensory language central loss At the same time, sports and sensory aphasia can occur accordingly. Parietal cortical lesions can cause cortical sensory disturbances. Due to the presence of the so-called "dumb zone" in the cerebral hemisphere, the tumors in this part (mainly index, anterior temporal lobe) are not localized. Symptoms (20%).
(2) Cerebellar astrocytoma: about 25% of astrocytomas, most of the tumors are located in the cerebellar hemisphere, followed by the ankle and the fourth ventricle, and a few are located in the cerebral cerebral horn. Children are more common in adults than in the cerebellar hemisphere. It is characterized by ataxia of the unilateral limb, the upper limb is more obvious than the lower limb, the affected limb is awkward, the holding is unstable, the muscle tension and the tendon reflex are low, and the tumor is located in the ankle or cerebellar hemisphere near the midline, and static ataxia may occur. , cerebellum gait and balance disorders, the upper axillary tumor showed a forward tilt, the lower axillary tumor tilted more backward, horizontal nystagmus more common in the cerebellar hemisphere tumor, the occurrence of rotation or vertical nystagmus indicates that the tumor may invade the brain stem, serious Cerebellar damage can occur in cerebellar language, and those with cerebellar tonsils can have neck resistance, forced head position or even cerebellar crisis.
(3) Thalamic astrocytoma: a typical thalamic syndrome, including:
1 lesions contralateral limbs paralyzed.
2 lesions on the opposite side of the body sensation (mainly with deep feeling).
3 lesions on the opposite side of the body spontaneous pain.
4 Mutual discomfort of the ipsilateral limb.
5 lesions ipsilateral dance-like exercise, but the typical manifestations of patients with thalamic tumors are rare, the clinical symptoms show great variation, the mental disorder is more obvious when the tumor develops forward and medial; the endocrine disorder is more prominent when developing to the hypothalamus In addition to the lesions on the opposite side of the occipital hemianopia, the development of the occipital occipital region can also affect the quadrants with large pupils, upper eyeball disorders, hearing impairment and other symptoms.
(4) Optic astrocytoma: more common in children, adults can also be seen, tumor growth is slow, most patients have a longer course, very few patients show acute course, clinical manifestations vary from tumor location, mainly for visual impairment and abnormal position of the eyeball Intracranial tumors can block the interventricular pores and the intracranial pressure increases. A small number of violations of the hypothalamus occur in the endocrine function. Intraorbital or cranial sputum communication can cause ipsilateral vision loss and visual field reduction. Irregular hemianopia can occur with cross-involvement. The damaged optic nerve often presents with primary atrophy, and the tumor that invades or is located in the optic chiasm can exhibit Foster-Kennedy syndrome.
(5) Third ventricle astrocytoma: The third ventricle astrocytoma originates from the anterior structure of the third ventricle, and may also originate from the third ventricle wall. The patient usually has no obvious symptoms in the early stage because of the cavity of the third ventricle. Small, tumor squeezing interventricular space or obstructing the upper mouth of the water tube and obstructive hydrocephalus, so the course of disease is short, typical patients have severe headaches, and the attack is related to exertion, head position and body position change, and Sudden loss of consciousness, affecting the endocrine changes of the hypothalamus, affecting the bottom of the third ventricle may occur in the epileptic seizures, affecting the hippocampus-thalamic-hypothalamic connections may cause mental disorders, memory loss, limb weakness and walking Unstable symptoms.
(6) Brain stem astrocytoma: 90% of brain stem tumors are gliomas, and more than half are astrocytomas. The tumors are mostly located in the pons, followed by the medulla oblongata, which is rare in the midbrain and the midbrain tumors. Oculomotor paralysis; pons tumor is the adductor nerve, facial nerve and trigeminal nerve involvement; medullary tumor can have posterior group of cerebral nerve palsy, tumor often invades the pyramidal tract on the ventral aspect of the brain stem and has "cross-paralysis", patient sensory disturbance and Cerebellar ataxia is very common, and there may be bilateral cranial nerve palsy, bilateral pyramidal tract signs and increased intracranial pressure.
Examine
Astrocytoma examination
Laboratory inspection
Lumbar puncture should be regarded as contraindication for patients with obvious increased intracranial pressure. Generally, astrocytoma shows increased intracranial pressure in different degrees. Cerebrospinal fluid examination is mostly normal and protein content is increased, which is close to the ventricle or subarachnoid. The cavity is particularly obvious, but the normal protein content of the cerebrospinal fluid cannot exclude the presence of the tumor.
Film degree exam
1. Neuroelectrophysiological examination: EEG has some help for epilepsy as the first symptom, mainly as focal low amplitude slow wave, partly as extensive moderate or severe abnormality, visual evoked potential (VEP) The examination is helpful for optic glioma and occipital lobe tumors, and brainstem auditory evoked potential (BAEP) is helpful for the diagnosis of tumors in the brain stem and cerebellum.
2. X-ray examination: Most patients with head X-ray plain film showed increased intracranial pressure, some of which can be seen in punctate or arcuate calcification. Optic nerve tumors can be seen to enlarge the optic nerve hole and can cause deformation of anterior bed and saddle nodules. "Pear-shaped sella", cerebral angiography showed vascular compression displacement, rare tumor staining and pathological blood vessels, ventricle tumors showed ventricular displacement and filling defects; cerebellar tumors showed symmetric expansion above the third ventricle, The lower part of the aqueduct is flexed, the fourth ventricle is compressed and displaced to the contralateral side, and the brainstem tumor shows the midbrain aqueduct and the upper part of the fourth ventricle are displaced to the dorsal side, becoming narrow or elongated.
3. CT examination: fibrous and protoplasmic astrocytoma, due to tissue water content of 81% to 82%, CT is low density, more uniform, no significant effect of occupying effect, no hemorrhage or necrosis There is no obvious edema in the tumor, except for a few cases. Generally, the contrast agent is not enhanced or slightly enhanced. It varies according to the location and size of the tumor, and the corresponding occupying effect is observed. The third ventricle astrocytoma is visible. After obstructing the third ventricle and Moro's hole, it causes dilatation of the bilateral ventricles, obstructive hydrocephalus, and the tumor itself has a slightly high density or mixed density. Contrast agent enhancement can be seen. The optic nerve tumor can be seen as a fusiform enlargement of the optic nerve. Internal and intracranial, sometimes dumbbell-shaped, cerebellar astrocytoma on the CT, the parenchymal part of the tumor is low (or) mixed density lesions, the contrast agent can be slightly enhanced after the enhancement, while the cystic part is always low density Shadow, the wall of the capsule may be ring-shaped or curved, and the astrocytoma of the brainstem may be thickened on the CT, bilateral asymmetry and tumor lesions with low density or mixed density. CT shows brain stem Glioma is not as good as M RI is ideal, and some tumors have an equal density on CT, which makes the tumor difficult to find on CT. At this time, MRI can clearly show the tumor shadow. There were low-density or heterogeneous low-density and high-density mixed lesions on CT, 90% of tumors had obvious tumor occupying effect, with peritumoral edema, 20% had cystic changes, and 10% showed calcification.
Hair cell astrocytoma CT can clearly show tumor shadow, tumor is equal density on CT, some tumor enhancement is not obvious, but some can be significantly enhanced, anterior pathway type, hypothalamic type and brainstem tumor boundary It is clear that the destruction of the anterior wall of the sella can be seen in the CT bone window, forming a "J" shaped sella.
4. MRI examination: Astrocytoma showed low signal on T1W on MRI, and T2W showed high signal. MRI could clearly show the degree of tumor infiltration of brain tissue. After augmentation, astrocytoma was generally not strengthened, and a few tumors had peripheral spots. Degree-enhanced imaging, benign astrocytoma due to tumor growth, increased intra- and extra-tumor water, resulting in prolonged T1 and T2, showing a low signal of T1-weighted images, a high signal of T2-weighted images, uniform signal intensity, and mild peritumoral edema. The increase of Gd-DTPA injection is not obvious. With the growth of the tumor, the cystic changes in the tumor make the MRI uneven. The tumor and surrounding edema are not easily distinguished on the T1-weighted image, and the tumor can be slightly enhanced. Malignant astrocytoma is a mixed signal on the T1 weighted phase, with low signal as the main signal, with lower signal or high signal, which reflects necrosis or hemorrhage in the tumor. The T1 weighted image shows high signal and the signal intensity is uneven. In the curved or dot-like low-signal region caused by tumor blood vessels, the tumor signal is lower than the surrounding edema signal on the proton density-weighted image, while the tumor internal necrosis signal is higher than the surrounding edema signal; On the long TE image, the signal intensity of the necrotic area in the tumor is similar to the intensity of the surrounding edema signal, and the signal intensity of the tumor is relatively reduced. Due to the gliosis of the peritumoral tissue, a circle of low signal halo is sometimes seen around the tumor. Between edema and edema, this is more common in tumors with higher malignancy. The latter often has significant abnormal contrast enhancement, long duration of enhancement, and the reinforced part is plaque-like, linear, flower-ringed or nodular. However, tumor necrosis or hemorrhagic area does not increase contrast. Cerebellar astrocytoma can be encapsulated in the tumor, or it can be tumor in the capsule. At this time, the tumor nodule can be cured, and the tumor can occur in the brain stem to make the midbrain and pons And the medulla is obviously thickened.
On MRI, angiogenic T1W is a low signal, T2W is a high signal, and more morphological glioblastoma images are slightly uniform, no necrosis or hemorrhagic foci. After enhancement, 80% to 90% of tumors are enhanced. The tumor enhancement performance is different, and it can be ring-shaped, nodular, irregular, etc., and some tumors are uniformly strengthened.
MRI of hair cell astrocytoma can clearly show the enlarged optic nerve and enlarged optic chiasm. The hypothalamic type can be enhanced due to the uniform tumor signal. The cerebral and cerebellar tumors often have clear boundaries, mostly cystic, and tumors. Wall nodules are sometimes strengthened.
Diagnosis
Diagnosis and diagnosis of astrocytoma
diagnosis
Diagnosis can generally be made based on the patient's clinical presentation and imaging studies.
Differential diagnosis
1. Oligodendroglioma: intratumoral calcification is one of the characteristics of oligodendroglioma, with a calcification rate of 50%-80%, morphologically punctate, or spotted, or curved. The latter has certain characteristics in the diagnosis of oligodendroglioma. In addition, the tumor of oligodendroglioma is often larger, and the peritumoral edema is relatively light, less than 1/3 of the tumor. However, calcification is also seen in astrocytoma, and its incidence is higher than oligodendroglioma, so when the subcortical region of the brain shows calcified nodules or masses, astrocytoma should usually be considered first.
2, vascular malformation: after repeated bleeding of deformed blood vessels, there is hemosiderin deposition and calcification, can be expressed as uneven density of nodules, but there should be no obvious edema around the lesion, there is no mass effect, unless there is acute bleeding .
3, astrocytoma and acute phase of cerebral infarction and demyelinating disease in the acute phase is difficult to identify, only enhanced follow-up can be differentiated, acute cerebral infarction and demyelinating disease after 5 to 10 days and 3 to 6 weeks, respectively The typical changes of lesions will appear on the head CT and MRI, and the astrocytoma will not change in the short-term imaging. The MRI of the hypothalamic hair cell astrocytoma can be significantly enhanced due to the uniform tumor signal. It is not easy to distinguish from solid craniopharyngioma and saddle germ cell tumor
In addition, different levels of astrocytoma need to be differentiated from brain softening lesions, brain abscesses, brain penetrating malformations, meningiomas, and brain metastases.
