Intracranial germ cell tumor

Introduction to intracranial germ cell tumor Intracranial germ cell tumors are called embryogenic germ cell tumors in the classification of the nervous system tumors of the World Health Organization. This tumor is very similar in histology to the seminoma of the testis and the malignant embryonal tumor of the ovary. It is called the brain germ cell tumor. basic knowledge The proportion of illness: 0.0001%-0.0003% Susceptible people: no special people Mode of infection: non-infectious Complications: disturbance of consciousness Stress ulcers Coma Swelling

The cause of intracranial germ cell tumor

Causes:

The etiology of germ cell tumors in the brain is unclear, and family history is also rare. It has been reported in the mediastinum of patients with Klinefelter syndrome (47,XXY, 47 chromosomes, 2 X and 1 Y sex chromosomes). Intracranial discovery of germ cell tumors, the typical characteristics of these patients are small testicles, fine seminiferous glass-like changes, no sperm, it is speculated that the occurrence of germ cell tumors in the mediastinum and intracranial is the mutation of the original reproductive genital differentiation leading to reproduction Cell migration, changes in differentiation and its tendency to malignant. Chromosomes often occur in patients with germ cell tumors in the brain, including non-random chromosome number abnormalities and structural ectopic. In testicular germ cell tumors, 80% exhibit characteristic chromosomal structural abnormalities, and chromosome 12 short arm and other arm chromosomal abnormalities (i12p), many non-germ cell tumors and extragonadal germ cell tumors also have i12p malformations.

During embryonic development, primordial germ cells are clearly visible in the fourth week of the embryo. They appear in the endoderm cells on the wall of the yolk sac, adjacent to the place where the allantois occur. When the embryo begins to fold, the primordial germ cells are in the midline from the yolk. The wall of the capsule migrates to the genital ridge through the dorsal mesenteric of the hindgut, and enters the mesenchymal tissue to become the primitive cord, and then gradually develops into a mature gonad. During this migration, the primordial germ cells spread throughout the embryo, and when these migrations are versatile When stem cells do not complete normal evolution and stay, they are likely to become tumors. At present, it is more consistent that germ cell tumors are a group of undifferentiated tumors derived from primordial germ cells.

Pathogenesis:

Tumors vary in size. Small ones are like peanuts. The larger ones can be like fists. The surface of the tumor is gray-red and invasive. It is not clear with the surrounding brain tissue, but it can also have a pseudo-envelope. The tumor texture is soft. It is brittle, in the form of fine granules, partially cystic, and can be removed by suction; a few may have hemorrhage, necrosis, less calcification of the tumor, if any may be in the form of a pellet, located in the center or periphery of the tumor, the tumor may be in the saddle area Infiltrating the optic nerve and optic chiasm, sometimes affecting the lower part of the thalamus upwards, the giant can protrude into the third ventricle, and even the interventricular space of the obstruction causes the ventricle to expand. The person in the pineal region can penetrate the third ventricle wall forward, pressing down and Infiltrate the quadrilateral, press the upper cranial fossa back and down, and infiltrate and compress the corpus callosum upwards.

Under light microscopy, tumor cells have two components: large cells resemble epithelial, pale, cytoplasm rich, polygonal, sometimes unclear, conventional staining is red; nucleus is located in the center of cytoplasm or slightly biased, mostly round Shape, the nuclear membrane is clear, the nuclear chromosome is sparse, it looks like a vacuole, the mitotic figures are common, and the other is a small cell with very few cytoplasms. It looks like a naked nucleus, is round, and has a rich chromatin. Lymphocytes are difficult to distinguish. In fact, they are immune-reactive lymphocytes and plasma cells. Large epithelioid cells often aggregate into cells of different sizes and irregular shapes. There are blood vessels and fibrous tissue bands, and small lymphoid cells are often distributed. Around the blood vessels, there are small pieces or focal necrosis in the tumor cells, and there are small hemorrhages with occasional small calcification.

Under electron microscopy, cells have two components: large cells are germ cells, small cells are lymphocytes or macrophages, and germ cells are large in size and polygonal in shape, containing one or more large and round nuclei, pale and sparsely electrons. Sexual, nucleolar prominent, often forming nucleolar velvet cells, cytoplasm containing a small amount of granular endoplasmic reticulum, a large number of nucleoprotein bodies, glycogen particles and a small amount of Golgi complex, a small number of mitochondria, central granules and microtubule structure The liposome plasmid is large and has a large vesicular shape. There is no basement membrane outside the large cell, and occasionally dysplastic punctate cells are connected between the cells. The small cells are clearly small lymphocytes under electron microscope and tend to cluster. The nucleus is round, the perinuclear nucleus is small, the cells are small and poor, but the whole electron density is much higher than that of the germ cells. Sometimes the macrophages are active, close to the tumor cells, and even embedded in the tumor cells, causing them to break down into broken pieces. Block, and phagocytosis and digestion, this phenomenon is called intracellular digestion of phagocytosis.

In immunohistochemistry, it can be identified according to the antigen associated with the tumor. The germ cells are positive for the placental alkaline phosphatase and are expressed on the cell membrane.

Half of the germ cell tumors are positive for human chorionic gonadotropin (HCG) expression, but are mostly expressed on syncytiotrophoblastic giant cells, ie, when the syncytiotrophoblasts of germ cells develop, and HCG expression is present in mixed germ cell tumors. Fetal globulin is negative, but levels in serum and cerebrospinal fluid are sometimes increased, indicating conversion to embryonic cancer.

Intracranial germ cell tumor prevention

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

Some related factors of tumorigenesis are prevented before the onset, and many cancers can be prevented before they are formed. A report in the United States in 1988 compared the international malignant tumors in detail and proposed many external factors of known malignant tumors. In principle, it can be prevented, that is, about 80% of malignant tumors can be prevented by simple lifestyle changes, and traced back. In 1969, Dr. Higginson's research concluded that 90% of malignant tumors are caused by environmental factors," "Environmental factors", "lifestyle" refers to the air we breathe, the water we drink, the food we choose to make, the habits of activities, and social relationships.

2. Improve the body's immunity against tumors: can help to strengthen and strengthen the body's immune system and cancer.

The focus of our current cancer prevention efforts should first focus on and improve those factors that are closely related to our lives, such as quitting smoking, eating properly, exercising regularly, and losing weight. Anyone who follows these simple and reasonable lifestyles can Reduce the chance of cancer.

The most important thing to improve the function of the immune system is: diet, exercise and control troubles. Healthy lifestyle choices can help us stay away from cancer. Maintaining good emotional state and proper physical exercise can keep the body's immune system at its best. Tumors and prevention of other diseases are equally beneficial. Other 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 we mainly understand the diet in preventing tumorigenesis. Some questions.

Intracranial germ cell tumor complications Complications, disturbance of consciousness, stress ulcer, coma, swelling

If surgery is performed, different complications may occur depending on the surgical method. For example, the central vein of the injury may cause postoperative hemiplegia, and the recovery may be incomplete. Intracerebral vein and cerebral venous injury may lead to coma, partial tumor resection. If the hydrocephalus is not relieved, or the obstructive hydrocephalus is caused by swelling of the brain tissue after surgery, shunt surgery is required. If the hypothalamic lesion can cause abnormal body temperature, disturbance of consciousness and stress ulcer, antacids should be given. Awakening drugs, symptomatic treatment, etc., surgical wounds are large, intraoperative hemostasis can cause intraventricular blood accumulation, intraoperative strict hemostasis, postoperative changes should be promptly reviewed CT for symptomatic treatment.

Symptoms of intracranial germ cell tumors Common symptoms Skull hyperplasia Increased intracranial pressure Hearing decline Reactive dull edema Drowsiness Diplopia development pause Hypothalamic lesion Visual field defect

Intracerebral germ cell tumors grow faster, most of the disease course is less than 1 year. The disease course is recorded in the literature from 2 days to 6 years, with an average of 7 months. The symptoms and signs of germ cell tumor mainly include increased intracranial pressure and local brain localization sign. And endocrine symptoms, etc., the development of the symptoms and signs are generally preceded by increased intracranial pressure, followed by quadrilateral compression symptoms and hypothalamic symptoms, and a small number of patients with quadrilateral compression as the first symptom.

1. Increased intracranial pressure symptoms

Germ cell tumor can open or block the upper end of the aqueduct, causing obstructive hydrocephalus. When the tumor is further enlarged, it compresses the posterior part of the third ventricle or the upper end of the aqueduct, making the obstructive hydrocephalus more prominent. Almost all patients have symptoms and signs of increased intracranial pressure, mainly manifested as headache, nausea and vomiting, double vision, optic disc edema, children can have head circumference enlargement, etc., and can be followed by optic atrophy and nerve palsy.

2. Local positioning sign

The most common localization symptom is Parinaud syndrome. This is the first time that Parinaud pointed out that in the pineal region tumors, there may be upper vision, pupillary photoreaction and dysregulation. Some of the patients have combined lower vision and pupillary photoreaction. Involuntary or widowed, the regulation response is weakened and Aropilin is an important sign of germ cell tumor. About half of the patients may have cerebellar symptoms, such as unstable holdings, walking shaking, nystagmus, etc. Hemiplegia, etc., tumor compression of the hypothalamus and medial geniculate body may appear bilateral tinnitus and hearing loss, others include epilepsy, cranial nerve (III, IV) incomplete paralysis, visual field defects.

3. Endocrine symptoms

Sexual precocity and giant genitalia are prominent endocrine symptoms of the disease, so they have a large diagnostic value, but sexual development may be paused or delayed. The incidence of sexual developmental disorders in children under 15 years old is 10% to 37.5%. Precocious puberty accounts for the majority of male cases, and hypothalamic lesions may present with diabetes insipidus, lethargy, obesity, developmental disorders, and sexual dysfunction.

4. Transfer

Because the germ cell tumor tissue is loose, it is easy to fall off, so there is a tendency to implant metastasis, often along the subarachnoid space to the basal pool, ventricular system and spinal cord metastasis, the transfer rate is generally between 10% and 37%, individual cases can be Extracranial distant metastasis, such as under the scalp, lungs, etc.

Examination of intracranial germ cell tumor

1. Blood:

The blood levels of chorionic gonadotropin, alpha-fetoprotein and carcinoembryonic antigen can be elevated in the patient's blood, and can be restored to normal after surgery. The recurrence or dissemination is increased again. 11 cases of germ cell tumors have been reported abroad, and all patients have blood chorionic villi. Gonadotropin or alpha-fetoprotein is elevated, so most scholars believe that patients with elevated chorionic gonadotropin or alpha-fetoprotein before surgery have a poor prognosis.

2. Cerebrospinal fluid:

Most patients have increased pressure. Some patients have mild to moderate increases in cerebrospinal fluid protein content. Chorionic gonadotropin or alpha-fetoprotein in cerebrospinal fluid can be significantly increased. Cerebrospinal fluid cytology can sometimes detect tumor cells. Epithelioid cells can be found in cerebrospinal fluid in 70% of cases. But does not necessarily mean that spinal cord metastasis occurs.

3. Skull flat: can show signs of increased intracranial pressure, 40% to 60% of patients may have abnormal calcification of pineal gland, especially when calcification occurs in children aged 10 to 15 years, calcification diameter exceeds 1cm Calcification down to the rear is a strong evidence for the diagnosis of germ cell tumors.

4. Radionuclide scanning: continuous brain scintillation tomography scan, the vast majority of visible nuclide accumulation in the tumor, the diameter is greater than 1.5cm.

5. CT scan: CT scan can accurately determine its size, location and its surrounding relationship.

Sweep CT can be seen with the same density or slightly higher density of gray matter, and the chance of calcification of germ cell tumor in pineal area is much higher than that of sellar cell tumor in saddle area. When the growth of germ cell tumor in pineal region is sometimes calcified pine The fruit body (in the form of a pellet) is wrapped in it, so the calcified "shot" may be in the tumor, or in the periphery of the tumor, often on the side or the back, even pushed to the front, the shape of the tumor is round Irregular or butterfly-shaped, the latter has characteristic value in the diagnosis of germ cell tumors. The normal human pineal calcification rate is about 40%, and the pineal calcification rate of patients with germ cell tumors is nearly 100%; Upper germ cell tumors may be free of calcification or fine calcification.

Enhanced CT: When CT scans find lesions, it should be injected immediately for CT intensive scan, showing moderate to obvious uniform enhancement, a small number of intensifications can be uneven, can show smaller cystic changes, so children or adolescents CT found a slightly high-density mass in the pineal region, and the injection has uniform enhancement (a few can be uneven). If there is bullet-like calcification, it is strongly suggested to be a germ cell tumor. The saddle-top germ cell tumor is located in the midline funnel and/or It is not uncommon for the pituitary gland to enter the saddle, and it is not uncommon to invade the pituitary gland. The saddle-top germ cell tumor can be round or lobulated. CT scan and enhancement are similar to the pineal region, but some scholars have pointed out that this part of the germ cell tumor is fresh. Calcification occurs. In addition to the above-mentioned "single-on" tumors, the most common type of germ cell tumor is "two or three germ cell tumors" when performing CT examination.

CT examination has great value for germ cell tumors, especially for tumor calcification and ventricular enlargement or displacement. Different subtypes of germ cell tumors have their own unique manifestations, sometimes combined with clinical, and even tumor qualitative diagnosis.

6. MRI examination: MRI is very clear to show small germ cell tumors (diameter <1cm) or spinal cord metastases in the saddle; it shows that the pineal region germ cell tumors are often round, elliptical or irregular, most T1 is Equivalent or slightly lower signal, T2 is slightly higher signal, and a few can be equal signal; uniform strengthening after injection, clear boundary, sometimes only a few moderate or uneven enhancement, there are reports of 20% to 58% of reproduction There are small cystic changes in cell tumors. These capsules are caused by protein liquid or necrotic liquefaction. They are usually very small. Sometimes there are small hemorrhages in the tumor, which is high signal in T1. The pineal region can invade the midbrain. And the thalamus, there is a peripheral high-signal shadow on the T2 image, MRI shows a comprehensive coverage of tumor implantation or dissemination, except for the multiple lesions of T1 and T2 images, and the lesions are obviously enhanced after injection, and the ganglion germ cell tumor is also T1 or lower signal, while T2 slightly higher signal, can be evenly enhanced after injection, and some show atrophy of the ipsilateral cortex.

Diagnosis and identification of intracranial germ cell tumor

diagnosis

For children and adolescents with increased intracranial pressure, ocular symptoms and precocious puberty, they should be highly suspected of this disease, supplemented by the above examinations, and can be diagnosed in time, especially in upper vision, sexual development disorders and pupils. It has important diagnostic significance for this disease.

Differential diagnosis

1. Pineal region cyst

For benign lesions, the rate of autopsy abroad is as high as 40%, most of which are small, only found by chance during MRI examination. Most of them have small and round cysts in the pineal region on MRI, mild ring enhancement after injection, and sometimes large cysts. The quadrilateral canopy can be slightly compressed. CT shows that the liquid and cerebrospinal fluid ratio is equal to high density, no clinical symptoms, no hydrocephalus, and most of them do not require surgery.

2. Pineal cell tumor

That is, from the pineal parenchymal cells, including pineal somatic tumors and pineal blastomas, the former are mostly round lesions with clear boundaries, rarely spread through the cerebrospinal fluid, pineal somatic tumors are malignant, local Infiltration, usually large in size and uneven in texture. There may be calcification around the pineal cell tumor. After injection, there may be uniform or uneven enhancement. Sometimes the nerve image is not easy to distinguish from the pineal region germ cell tumor, but the pine cone. Somatic cell tumors are not sexually predisposed, and the average age is larger than that of germ cell tumors (more than 20 years old).

3. Glioma

Mostly astrocytoma, very few ependymoma, mostly originated from the quadrilateral or the posterior wall of the third ventricle, the tumor is sometimes small, but early cause obstructive hydrocephalus, MRI see tumor and quadrilateral Melt into one, press the aqueduct to make it narrow or locked. After injection, it is not strengthened or slightly strengthened. Sometimes, the affected thalamus and brain stem are swollen, and high signal is visible on the T2 image.

4. Meningioma

Meningioma in the pineal region is rare, mostly in adults (usually occurring in 40 to 60 years old), often originating from the free margin of the cerebellar stenosis, so it is often not in the middle, the tumor is often round or elliptical, CT is uniform density, MRI In the T1 image, it is a uniform high signal, which can be obviously evenly enhanced after injection, and can show the meningeal tail sign on the cerebellum (the coronary scan shows more clearly).

5. Lipoma

It can occur in the pineal region, which is a congenital lesion. It is actually the result of ectopic or blurred adipose tissue during fetal growth and development. Most of them are small, do not cause symptoms, and do not require surgery.

6. Epithelioid cyst or dermoid cyst

Can occur in the pineal region, can be larger, CT is low density, CT value is lower than cerebrospinal fluid; MRI is low signal in T1 image, T2 image can change greatly, from low signal to uneven signal, epithelial The cyst boundaries may be irregular and some of the borders may be worm-like.

7. Arachnoid cyst

Sometimes the cyst can be larger, the density or signal in the capsule is similar to cerebrospinal fluid in CT and MRI, the wall of the capsule is thin, and it can be slightly strengthened after injection.

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