Intracranial melanoma

Introduction to intracranial melanoma Intracranial melanoma is a rare intracranial malignant tumor. The clinical course progresses rapidly, the degree of malignancy is high, and the diagnosis and treatment is very difficult. The intracranial melanoma is rich in blood supply, easy to invade vascular disease and cause intratumoral hemorrhage and extensive bloody broadcasting. The metastasis is very poor. basic knowledge The proportion of illness: the incidence rate is about 0.001% Susceptible people: no special people Mode of infection: non-infectious Complications: coma, cerebral palsy, hydrocephalus

Intracranial melanoma etiology

There are two kinds of primary and secondary intracranial melanoma. The former is rare, and the latter is caused by the transfer of melanoma in the skin, mucous membrane, retina, etc. to the brain.

Melanoma can be composed of epidermal melanocytes, sputum cells or dermis into melanocytes. The tumor originates from the neural crest of the ectoderm. The melanocytes are arranged between the epidermis and the basal cells. After the cells produce pigment, the melanin particles are transported into the basal cells and hair through the dendrites. The true cause of normal melanocytoma is unclear and may be related to the following factors:

Benign melanin plaque (30%):

That is, black scorpion, in which the junction is most likely to be malignant, mixed sputum is less, and endothelium is rarely malignant. However, most of the scalp melanoma is not converted from black sputum, so some people think that intracranial melanoma is not completely related to black sputum.

Sunlight and ultraviolet radiation (20%):

The scalp melanoma is more common in the exposed area. According to Israeli statistics, the annual incidence rate of agricultural workers is 15.4/100,000, which is higher than that of urban residents; residents living in coastal areas are higher than those living in mountainous areas. The incidence of melanoma has more than doubled since the 1980s and is estimated to be associated with damage to the atmospheric ozone layer and excessive exposure of the skin to ultraviolet light.

Race (10%):

Whites have a higher incidence than colored people. For example, the annual incidence of whites in the United States is as high as 42/100,000, while that of blacks is only 0.8/100,000.

Other (10%):

Genetic trauma, chronic mechanical stimulation and other factors can also be pathogenic factors.

Pathogenesis

Intracranial melanoma cells are found in the bottom of the brain and in the sulcus of the cerebral cortex. The primary intracranial melanoma is derived from the pia mater vesicle or arachnoid melanocytes, which spread through the meninges and spread to the brain parenchyma. In the form of direct implantation or blood transfer, the tumors in the brain are often multiple, widely distributed in the meninges, arachnoid, cortex and subcortical regions. The intracranial metastatic melanoma is distributed with blood flow, mainly in the brain. Meningeal metastasis can also occur at the same time. Severe intracranial melanoma can affect all central nervous system. Highly malignant can even invade the skull and spinal cord tissue. Tumor tissue can also infiltrate and erode blood vessels on the surface of the brain, leading to extensive subarachnoid hemorrhage.

It is difficult to determine the intracranial melanoma as primary or secondary by simple histopathological examination. Because the morphology of the two is basically the same, the tumor is grayish-black, because the tumors are different in shape, and the tumors in the brain are often present. Nodular, the boundary is still clear, the tumor of the meninges or the near cortex is diffuse or carpet-like. If the near skull base often surrounds the surrounding cranial nerves, causing multiple cranial nerve damage, the spinal cord is often accompanied by the corresponding segment of the spinal cord. Symptoms of nerve roots, microscopic examination showed that the tumor cells were fusiform or polygonal, and the nucleus was round or oval, often masked or squeezed to one side by the pigment. There was little nuclear fission, and there were granules or blocks in the cytoplasm. The melanin, the tumor cells are not arranged in a certain way, aggregated in the subarachnoid space, or extend outward along the blood vessels. Intracranial melanoma is difficult to interact with melanoma in the formation, morphology and biological behavior of the brain. The tumor is different.

Intracranial melanoma prevention

There is no effective preventive measure for this disease. Early detection and early treatment are the key to the prevention and treatment of this disease.

Intracranial melanoma complications Complications, coma, cerebral hydrocephalus

Postoperative intracranial pressure may increase, coma, cerebral palsy, mainly due to cerebral edema, intracranial hematoma and hydrocephalus, rough operation during operation, excessive traction, excessive exposure time in the field, injury to the aorta, vein or Excessive blood loss can easily lead to postoperative cerebral edema. The occurrence of intracranial hematoma is mainly related to incomplete hemostasis, blind hemostasis and unstable blood pressure fluctuations. If the condition worsens within 12 hours after surgery, the intracranial hemorrhage and ventricle should be considered first. Surgery or cranial fossa surgery in the cerebral cistern and its immediate or indirect effects on cerebrospinal fluid circulation can cause hydrocephalus, which gradually aggravates the symptoms of postoperative intracranial pressure.

Intracranial melanoma symptoms Common symptoms Increased intracranial pressure hydrocephalus dysfunction nausea and vomiting hemian meningitis edema

The clinical manifestations vary according to the location, size, size and number of tumors.

1. Increased intracranial pressure symptoms

It is characterized by headache, progressive aggravation, nausea, vomiting, and optic disc edema.

2. Nervous system damage localization symptoms

Tumors occur in the brain parenchyma or invade the cerebral ventricle may occur hemiplegia, aphasia, hemianopia, epilepsy, mental symptoms, etc., occurs in the spinal cord may have corresponding spinal segmental sensation, dyskinesia.

3. Subarachnoid hemorrhage or tumor stroke symptoms

When a tumor invades a blood vessel, hemorrhage may occur in the tumor, in the brain parenchyma or in the subarachnoid space, and sudden conscious disturbance, vomiting, and even cerebral palsy may occur in the clinic.

4. Other tumors are located at the base of the skull, which can invade multiple groups of cranial nerves. Multiple groups of cranial nerve damage occur. Stimulation of tumor metabolites on the pia mater or arachnoid may produce arachnoiditis or meningitis symptoms, arachnoid inflammatory reaction. And tumor cells spread in the subarachnoid space, aggregation can cause hydrocephalus, and then symptoms of increased intracranial pressure.

Examination of intracranial melanoma

Lumbar puncture brain pressure is often high, protein in the cerebrospinal fluid, the number of cells are increased to varying degrees, such as tumor invasion and blood vessels caused by bleeding, cerebrospinal fluid is often bloody.

Cerebral angiography

Intracranial melanoma is rich in blood supply, easy to invade the blood vessel wall and cause intratumoral hemorrhage and extensive blood transfer. Cerebral angiography shows abundant tumor circulation and staining, which has high diagnostic value.

2. CT scan

The location, size, number and extent of the tumor can be displayed, but the diagnostic specificity is poor. The CT scan lesions are mostly high-density shadows, and a few can also be equal-density or low-density shadows, and the enhanced scans are uniform or non-uniform.

3.MRI

The diagnostic sensitivity and specificity for intracranial melanoma is better than CT. Typical MRI is short T1 and short T2 signals. A few atypical MRI are T2 signals such as short T1 and long T2 or equal T1, depending on the tumor. The content and distribution of paramagnetic melanin and the amount of paramagnetic methemoglobin in intratumoral hemorrhage.

Diagnosis and diagnosis of intracranial melanoma

Diagnostic criteria

Because intracranial melanoma grows fast and has a short course of disease, it is often misdiagnosed as arachnoiditis, cerebrovascular disease, intracranial glioma and epilepsy. Clinically, the course of disease is short, and the symptoms of increased intracranial pressure develop rapidly. CT and MRI examination Apparent occupying effect, the history of melanoma surgery on the surface or viscera, the possibility of intracranial melanoma should be considered. The dura mater in the tumor area, the brain tissue or the tumor is black lesions, which is reliable for the diagnosis of intracranial melanoma. Basis, but it is difficult to achieve a qualitative diagnosis before surgery, but the more prevalent conditions for the diagnosis of primary intracranial melanoma are:

1 No melanoma was found in the skin and eyeballs.

2 The above site has not been treated with melanoma before.

3 visceral no melanoma metastasis.

Differential diagnosis

Intracranial glioma

It is clinically similar to intracranial melanoma and is easily misdiagnosed. CT and MRI have obvious space-occupying effect and large edema zone. In MRI scan, the lesions show uniform short T1 and short T2 signals are characteristic features of melanoma.

2. Cerebrovascular disease and spontaneous subarachnoid hemorrhage

Partial intracranial melanoma due to rapid growth, tumor hemorrhage, tumor tissue can also invade the surface of the blood vessels leading to subarachnoid hemorrhage, CT and MRI scan can identify, children with spontaneous subarachnoid hemorrhage in addition to considering the intracranial In addition to congenital vascular malformations, the possibility of intracranial melanoma with bleeding should also be considered.

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