Germinoma of the brain is a dysontogenetic tumor of a more often malignant nature, localized in the deep structures of the brain. Germinoma of the brain can manifest itself as a combination of clinical signs of hydrocephalus with visual impairment, disorders of the psycho-emotional sphere and / or various neuroendocrine syndromes. Brain germinoma is diagnosed by a comprehensive comparison of clinical data, CT or MRI of the brain, blood test for the presence of biochemical markers of the tumor and histological examination of a sample of tumor tissue. Germinoma of the brain refers to X-ray and chemosensitive tumors, so these methods are successfully used in its treatment. The method of choice is surgical removal of the germinoma.
C71 Malignant neoplasm of the brain
Germinoma of the brain accounts for only 2% of all intracerebral tumors, but it is the most common tumor of the deep structures of the brain (pineal region, pineal body, III ventricle and pituitary region). The proportion of brain germs located in the pineal region accounts for about 56%. Germinomas of the brain, localized in the pituitary gland, account for 25%. In 75% of cases, a brain germinoma is a single tumor, in 25% of cases it is multiple in nature.
Germinomas of the brain occur mainly in the period from 10 to 20 years of life. According to some data, this type of tumors is more common in males. Germinoma of the brain is often malignant in nature and is prone to disseminated growth into the surrounding brain tissues. However, about ¼ of the brain germs are benign neoplasms.
Along with teratomas, choroid carcinoma, craniopharyngioma, colloidal cyst of the III ventricle, etc. neoplasms of the brain germinoma refers to dysontogenetic tumors, the cause of which are various disorders of embryonic development. And although the dysontogenetic theory of the occurrence of brain germs has not been definitively proven, the young age of the patients speaks in its favor. According to this theory, a brain germinoma appears due to violations of tissue differentiation and tissue migration at the initial stages of embryo development (I trimester of pregnancy).
Factors causing embryonic disorders are various adverse effects that affect the fetus indirectly through the mother’s body. For example, radiation exposure, various intoxications, contact with carcinogenic substances, infectious diseases (herpes, measles, severe flu, chlamydia, etc.).
Since the germinoma of the brain is localized near the III ventricle and tends to grow along the cerebrospinal fluid pathways, significantly disrupting the flow of cerebrospinal fluid, symptoms of hydrocephalus often come to the fore in its clinical picture. As a rule, patients complain of an intense headache of a bursting nature, a feeling of pressure in the eyes, nausea unrelated to food, and even vomiting.
Due to its location near the chiasm of the optic nerves, germinoma of the brain is often manifested by visual disturbances: decreased visual acuity, double vision, visual field defects. Also, germinoma of the brain can be accompanied by disorders of the psycho-emotional sphere and memory disorders. The location of the tumor in the pituitary gland leads to disruption of the functioning of the hypothalamic-pituitary system and the development of various neuroendocrine syndromes: diabetes insipidus, panhypopituitarism, menstrual cycle disorders, anovulation and amenorrhea in women.
The first step in the diagnosis of germinoma of the brain is a thorough survey and neurological examination of the patient, which allow the neurologist to identify not only the symptoms of hydrocephalus, but also signs of damage to the median structures. Echo-encephalography helps to diagnose an increase in intracranial pressure, in the case of a large tumor size, echo-signs of displacement of the middle structures of the brain are determined during its implementation.
The next link in the diagnosis of brain germinoma is the use of CT and MRI of the brain. Tomographic methods of investigation allow us to establish the tumor nature of the formation, its size and location. Approximately 40% of patients with brain germinoma have a characteristic feature of this tumor — tumor infiltration of the visual tubercles and the presence of a petrificate located in the middle (butterfly symptom). In favor of germinoma, the spread of the tumor process along the lateral ventricles and metastasis to the infundibular region of the III ventricle can speak.
The determination of biochemical markers in the blood: chorionic gonadotropin (hCG), alpha-fetoprotein (AFP) and placental alkaline phosphatase (PCP) is of auxiliary importance in the diagnosis of germinoma and in the assessment of the condition of the disease.
The final diagnosis of “brain germinoma” can be established based on the results of a study of the tumor material obtained by conducting a stereotactic biopsy. But due to the significant heterogeneity of the tumor, this diagnostic method does not always have sufficient reliability. More accurate results are obtained by a thorough morphological examination of various areas of the tumor after its removal. However, given the high radiosensitivity possessed by the brain germinoma and certain difficulties of surgical interventions on the mid-brain structures, many neurosurgeons consider it advisable to conduct a stereotactic biopsy if a brain germinoma is suspected.
Brain germinoma needs to be differentiated from other brain tumors (astrocytomas, gliomas, ganglioneuromas, hematoblastomas, glomus tumors, medulloblastomas), as well as from brain abscess, intracerebral hematoma, colloidal cyst of the III ventricle.
Since germinoma of the brain is a radio- and chemosensitive tumor, the main therapeutic tactic for its diagnosis is radiation therapy. Tumor irradiation is contraindicated in childhood due to the negative effect of ionizing radiation on developing brain tissues. Therefore, in children and when radical radiation therapy is impossible due to the extensive tumor process, they resort to polychemotherapy. Radiation and chemotherapy are also used as an adjunct to surgical treatment in the case of malignant germinoma.
Removal of germinomas and other tumors of the middle structures is still one of the most difficult tasks of neurology and neurosurgery. The main problem is connected with the implementation of access to tumors of such deep localization. Optimization of the accesses used, the ability to plan the course of the operation using neuroimaging methods, the emergence of more advanced surgical instruments have led to the fact that nowadays surgical treatment is the method of choice for patients diagnosed with brain germinoma.
The germinoma of the brain is removed by various surgical approaches, the choice of which is carried out by a neurosurgeon after a thorough study of the localization and size of the tumor. If there are indications, the removal of germinoma is accompanied by one of the types of shunting operations: ventriculoperineostomy or ventriculocysternostomy. Surgical treatment is contraindicated if a brain germinoma is characterized by disseminated growth or inoperable location. A small-sized brain germinoma can be effectively removed using stereotactic radiosurgery, which consists in a single local irradiation of the tumor with a high dose of radiation.
Prognosis and prevention
Germinoma of the brain is characterized by a relatively favorable prognosis of both radiation therapy and surgical treatment. The five—year survival rate of patients reaches 95%, and the ten-year survival rate is 88%.
Preventive measures aimed at preventing the occurrence of germinoma include, first of all, the exclusion of various adverse effects on the mother’s body. Early registration and appropriate explanations from the obstetrician-gynecologist, who carries out pregnancy management, can help a woman to protect herself from the influence of various teratogenic factors (medicinal, industrial, etc.).