germ cell tumor
Introduction
Introduction to germ cell tumor Germ cell tumors are derived from the original germ cells, which occur in the pineal region, followed by the saddle-up pool. Tumors occur mostly in male adolescents, and germ cell tumors in the saddle are more common in women. Germ cell tumors are very sensitive to radiation. The tumor usually has no capsule, no calcification, hemorrhage, necrosis or cystic change. It is a low-grade malignant tumor, mostly invasive growth, often with varying degrees and forms of metastasis, easy to plant into the subarachnoid space and ventricular system. Spread. Histologically, tumors mainly contain two cellular components: epithelioid cells and lymphoid cells. The cause of germ cell tumors is not clear, and family history is rare. Germ cell tumors have been reported in the mediastinum and intracranial of patients with Klinefelter syndrome (47,XXY, 47 chromosomes, 2 X and 1 Y sex chromosomes). The typical characteristics of these patients are small testicles, seminiferous tubules, and azoospermia. It is speculated that the occurrence of germ cell tumors in the mediastinum and intracranial is the mutation of primordial genital warts that leads to changes in germ cell migration and differentiation. Its vicious tendency. basic knowledge The proportion of illness: 0.0025% Susceptible people: no specific population Mode of infection: non-infectious Complications: disturbance of consciousness stress ulcer
Cause
Germ cell tumor etiology
Germ cells are not differentiated (90%)
The cell tumor is derived from the original germ cells, which occurs in the pineal region, followed by the saddle-up pool. Tumors occur mostly in male adolescents, and germ cell tumors in the saddle are more common in women. Germ cell tumors are very sensitive to radiation.
The tumor usually has no capsule, no calcification, hemorrhage, necrosis or cystic change. It is a low-grade malignant tumor, mostly invasive growth, often with varying degrees and forms of metastasis, easy to plant into the subarachnoid space and ventricular system. Spread. Histologically, tumors mainly contain two cellular components: epithelioid cells and lymphoid cells.
The cause of germ cell tumors is not clear, and family history is rare. Germ cell tumors have been reported in the mediastinum and intracranial in patients with Klinefelter syndrome (47,XXY, 47 chromosomes, 2 X and 1 Y sex chromosomes). The typical characteristics of these patients are small testicles, seminiferous tubules, and azoospermia. It is speculated that the occurrence of germ cell tumors in the mediastinum and intracranial is the mutation of primordial genital warts that leads to changes in germ cell migration and differentiation. Its vicious tendency. The chromosomes of patients with germ cell tumors often have abnormalities, including non-random chromosome number abnormalities and structural ectopics. In testicular germ cell tumors, 80% exhibit characteristic chromosomal structural abnormalities, chromosome 12 short arm and other arm chromosomal abnormalities (i12p), and many non-germ cell tumors and extragonadal germ cell tumors also have i12p malformations.
During embryonic development, primordial germ cells are clearly visible at week 4 of the embryo, and they appear in the endoderm cells on the wall of the yolk sac, adjacent to where the allantois occur. When the embryo begins to fold, the primordial germ cells migrate from the yolk sac wall through the posterior mesenteric of the hindgut to the genital wart, and enter the mesenchymal tissue to become the primitive cord, and then gradually develop into a mature gonad. During this migration process, primordial germ cells are spread throughout the embryo, and when these migrating omnipotent stem cells do not complete their 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.
Prevention
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 improve 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.
Complication
Germ cell tumor complications Complications, disturbance of consciousness, stress ulcer
If hypothalamic damage can occur abnormal body temperature, disturbance of consciousness and stress ulcers.
Symptom
Germ cell tumor symptoms common symptoms sleepiness headache and vomiting visual impairment diabetes collapse
The prominent clinical manifestations are endocrine disorders / 8 /, manifested as upper visual impairment and precocious puberty, and may be associated with hypothalamic dysfunction, such as diabetes, polydipsia, lethargy and obesity. Other symptoms are related to the tumor site, and the pineal region tumor can block the midbrain aqueduct, causing intracranial hypertension. The tumor in the sellar region first showed visual impairment, followed by headache, vomiting, polydipsia, and hypopituitarism.
Germ cell tumors grow faster, most of the disease course is less than 1 year, and 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, local brain localization and endocrine symptoms. The order of development of symptoms and signs is generally the first increase in intracranial pressure, followed by symptoms of quadrilateral compression and hypothalamic symptoms. There are also a small number of patients with four-fold compression as the first symptom.
1. Symptoms of increased intracranial pressure: Germ cell tumor can open the upper end of the early compression or obstruction of the aqueduct, causing obstructive hydrocephalus. When the tumor is further enlarged, oppress the posterior part of the third ventricle or the upper end of the aqueduct to make obstructive Hydrocephalus is more prominent, so 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 expansion. In the later stage, optic atrophy and paralysis of the nerves can be secondary.
2. Local localization: The most common localization symptom is Parinaud syndrome. This is the first time that Parinaud first pointed out that the pineal region tumors may have upper vision, pupillary photoreaction and dysregulation. Some of the patients could not be combined with lower vision at the same time. The pupillary light was slow or dull, the regulation response was weakened, and the arrotropia was an important sign of germ cell tumor. About half of the patients may have cerebellar symptoms, which are characterized by unstable objects, walking and shaking, nystagmus, etc., and a small number of violations of the basal ganglia may occur. Tumor compression in the hypothalamus and medial geniculate body can cause bilateral tinnitus and hearing loss. Others include epilepsy, cranial nerve (III, IV) incomplete paralysis, and visual field defects.
3. Endocrine symptoms: Precocious puberty and giant genitalia are prominent endocrine symptoms of the disease, so it has a large diagnostic value. But it can also be seen that sexual development is paused or slow. The incidence of sexual developmental disorders in children under 15 years old is between 10% and 37.5%. Precocious puberty accounts for the majority of male cases. Hypothalamic damage can occur in diabetes insipidus, lethargy, obesity, developmental disorders, and sexual dysfunction.
4. Metastasis Because the germ cell tumor tissue is loose and easy to fall off, there is a tendency to implant metastasis, often along the subarachnoid space to the basal pool, ventricular system and spinal cord. The transfer rate is generally between 10% and 37%. In some cases, extracranial distant metastases can occur, such as under the scalp and lungs.
Examine
Germ cell tumor examination
Laboratory inspection
1. Blood: Human chorionic gonadotropin, alpha-fetoprotein and carcinoembryonic antigen can be elevated in the blood of patients. It can return to normal after surgery and rise again when recurring or spreading. 11 cases of germ cell tumors were reported abroad, and all patients had elevated levels of chorionic gonadotropin or alpha-fetoprotein in the blood. Therefore, most scholars believe that patients with elevated chorionic gonadotropin or alpha-fetoprotein before surgery have a poor prognosis.
2. Cerebrospinal fluid: The pressure of most patients is increased. The protein content of cerebrospinal fluid in some patients is mildly moderately increased, and the chorionic gonadotropin or alpha-fetoprotein in cerebrospinal fluid can be significantly increased. Cystic cells can sometimes be found in cerebrospinal fluid cytology. Epithelioid cells can occur in cerebrospinal fluid in 70% of cases, but do not necessarily mean spinal cord metastasis.
Other auxiliary inspections:
1. 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, calcifications are more than 1 cm in diameter, and calcification is displaced downwards and backwards, which is a powerful method for diagnosing germ cell tumors. evidence.
2. Radionuclide scanning : Continuous brain scintillation tomography scan, the vast majority of visible nuclide accumulation in the tumor, the diameter is greater than 1.5cm.
3. CT scan : CT scan can accurately determine its size, location and its surrounding relationship. Plain CT can be seen with the same density or slightly higher density of gray matter, and the chance of calcification of germ cell tumors in the pineal region is much higher than that of the saddle area. When the calcified pineal gland (in the form of a pellet) is sometimes surrounded during the growth of the pineal region germ cell tumor, the calcified "shot" may be in the tumor, or in the periphery of the tumor, often on the side. Or rear, even can be pushed to the front. The shape of the tumor is round, irregular or butterfly-shaped, and the latter has a 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 tumor is nearly 100%; the saddle upper germ cell tumor can be free of calcification or fine calcification.
Enhanced CT: When CT scans are found, the CT should be injected immediately for CT intensive scanning, showing moderate to obvious uniform enhancement, and a few enhancements are uneven, showing smaller cystic changes. Therefore, children or adolescents, CT found a slightly higher density of pineal body area, uniform injection of drugs (a few can be uneven), if there is bullet-like calcification, it is strongly suggestive of germ cell tumor. The saddle-top germ cell tumor is located in the midline funnel and/or pituitary gland into the saddle, and it is not uncommon to invade the neurohypophysis. The saddle upper germ cell tumor can be round or lobulated, and the CT scan and enhancement are similar to the pineal region, but some scholars have pointed out that there is little calcification in the germ cell tumor at this site. In addition to the above-mentioned "single-on" tumors, with regard to "multiple" germ cell tumors, the most typical is the discovery of 2 or 3 germ cell tumors at the time of CT examination. CT examination is of great value for germ cell tumors, especially for the calcification of the tumor and the enlargement or displacement of the ventricles. Different subtypes of germ cell tumors have their own unique manifestations, sometimes combined with clinical, and even qualitative diagnosis of tumors.
4. 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 enhancement after injection, clear boundary, sometimes only a few moderate or uneven enhancement. It has been reported that 20% to 58% of germ cell tumors have small cystic changes. These capsules are caused by protein liquid or necrotic liquefaction, usually very small, sometimes with small hemorrhage in the tumor, and high signal in T1. The pineal region can invade the midbrain and the thalamus, and there is a blurry high signal on the T2 image. MRI showed comprehensive coverage of tumor implantation or dissemination, except for the multiple lesions of T1 and T2 images, which showed clear lesions and marked enhancement after injection. The ganglion germ cell tumor is also T1 or the like, and T2 is slightly higher signal. It can be evenly strengthened after injection, and some show atrophy in the ipsilateral cortex.
Diagnosis
Diagnosis and differentiation of germ cell tumor
diagnosis
A diagnosis can be made based on the results of the examination and the symptoms.
Differential diagnosis
1. Pineal region cyst
For benign lesions, the rate of autopsy abroad is as high as 40%. Most of them are small and only found by chance during MRI examinations. Most of them have small and round cysts in the pineal region on MRI. They are mildly ring-shaped after injection. Sometimes the cysts are larger and can compress the upper quadrant. CT shows that the ratio of fluid to cerebrospinal fluid is equal to high density. Clinical symptoms do not cause hydrocephalus, and most do not require surgery.
2. Pineal cell tumor
That is, from the pineal parenchymal cells, including pineal somatic tumors and pineal blastoma, the former are mostly round lesions with clear boundaries, rarely spread through the cerebrospinal fluid; pineal blastoma is 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 neuroimaging is not easy to distinguish from the pineal region germ cell tumor, but the pineal parenchymal cell tumor has no gender tendency, and the average age is higher. Germ cell tumors are large (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 it causes obstructive hydrocephalus in the early stage. MRI sees the tumor and the four-fold body melt together, and compresses the aqueduct to make it narrow or locked. After the injection, it is not strengthened or slightly strengthened, sometimes it can be affected. The thalamus and brainstem swelled and a high signal was visible on the T2 image.
4. Meningioma
Meningioma in the pineal region is rare, mostly in adults (often occurring in 40 to 60 years old), often originating from the free margin of the cerebellar incision, so it is often not in the middle. Tumors are often round or elliptical, CT is uniform density, MRI is a uniform high signal in T1 image, and can be uniformly enhanced after injection, and can show signs of meninges on the cerebellum (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. The boundary of the epithelioid cyst may be irregular, and some of the borders may be worm-like.
7. Arachnoid cyst
Sometimes the cysts can be larger, and the intracapsular density or signal is similar to cerebrospinal fluid in CT and MRI. The wall of the capsule is thin and can be slightly strengthened after injection.
