What is the choroid plexus? In certain parts of the ventricles, the soft meninges and the blood vessels on them together with the ventricular epithelium form the choroidal tissue. In some parts, the blood vessels branch repeatedly into plexuses, and together with the soft meninges and ventricular epithelium on their surfaces, they protrude into the ventricles to form the choroidal plexus, which is the main structure for the production of cerebrospinal fluid. (Location and shape of choroid plexus) The cerebral crest fluid produced by the lateral ventricular choroid plexus flows through the interventricular foramen to the third ventricle, converges with the cerebral crest fluid produced by the third ventricle, flows through the midbrain canal to the fourth ventricle, and then together with the cerebral crest fluid produced by the fourth ventricular choroid plexus, flows into the cerebellar medullary pool through the median foramen of the fourth ventricle and the lateral foramen of the fourth ventricle, and rapidly spreads to the entire subarachnoid space, flows to the back of the brain, penetrates through the arachnoid granules to the superior sagittal sinus, which will flow into the circulation. What is a choroid plexus papilloma? Papilloma of choriod plexus papillomas (PCP) originates from the epithelial cells of the ventricular choroid plexus and has the same embryonic origin as ventricular meningioma, accounting for 0.4% to 0.6% of intracranial tumors and 2% to 5% of childhood brain tumors. The tumor cells are similar to the normal choroid plexus cells, with single layer of rectangular or dwarf columnar cells surrounding the vascular-rich connective tissue to form a regular papillary structure, swelling growth, clear demarcation with surrounding tissues, complete surgical excision and good prognosis. Choroid plexus papilloma mainly presents with symptoms of cranial hypertension due to hydrocephalus. This is mainly due to excessive secretion of cerebrospinal fluid by the tumor, which blocks the cerebrospinal fluid circulation, or due to adhesions in the subarachnoid space caused by tumor hemorrhage. It can have two types of manifestations: increased intracranial pressure and restricted neurological damage. Most patients have hydrocephalus and intracranial pressure increase. The causes include obstructive hydrocephalus due to direct obstruction of cerebrospinal fluid circulation by the location of brain tumor and traffic hydrocephalus due to disorder of cerebrospinal fluid production and absorption. The increased intracranial pressure in infants and children is directly related to the occurrence of hydrocephalus. In infants and children, increased intracranial pressure is manifested by an enlarged skull and increased fontanelle tension, indifference, drowsiness or irritability. In older children and adults, it may manifest as headache, vomiting, optic disc edema, and even paroxysmal coma. Severe hydrocephalus reduces cortical inhibition or the direct effect of tumor can lead to seizures. The manifestation of limited neurological damage varies depending on the location of the tumor. If the tumor is located in the lateral ventricle, half of them have mild cone bundle sign on the opposite side; if it is located in the posterior part of the third ventricle, it shows difficulty in upward vision of both eyes; if it is located in the posterior cranial fossa, it shows unstable walking, nystagmus and ataxic movement disorder. Individuals located in the lateral ventricles may present with a head mass. A history of spontaneous subarachnoid hemorrhage is seen in this disease. Most of the tumors are located in the ventricles of the brain, and some of them are mobile, so some patients present with sudden increase or relief of headache. This may be due to sudden obstruction of cerebrospinal fluid circulation after tumor movement. Treatment of choroid plexus papilloma The tumor is histologically benign and total surgical removal of the tumor is the most ideal treatment option. The blood supply comes from the anterior choroidal artery (for those within the lateral ventricles), the posterior medial or posterior lateral choroidal artery (for those within the three ventricles), and the posterior inferior cerebellar artery (for those within the four ventricles), etc. Sometimes it is more difficult to electrocoagulate the tumor vascular bleeding, so we should try to avoid resecting the tumor in pieces. Therefore, we should try to avoid resecting the tumor in pieces and find out the vascular tip of the tumor, electrocoagulate and then disconnect it, and try to remove the tumor completely. Since choroid plexus papilloma has rich blood supply, deep location and adjacent to important structures (such as optic thalamus and brainstem), it is difficult to operate, and it is easy to cause excessive blood loss or brainstem injury, and the mortality rate is high. However, the long and tortuous route of the blood supply artery makes it difficult to choose. However, with the development of microsurgery in recent years, the mortality rate has decreased significantly to less than 1%. However, for those who cannot completely remove the tumor and cannot relieve hydrocephalus, shunt surgery should be performed; for incomplete resection of choroid plexus papilloma, local radiation therapy should be performed, which is effective in reducing recurrence rate and prolonging survival; for those who have signs of recurrence or malignant change, radiation therapy should also be done.