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Pineocytoma of the pineal gland
Last reviewed: 18.10.2021
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A clearly localized brain tumor - pineocytoma of the pineal gland or pineal gland (corpus pineale) - occurs mainly in adults. [1]
According to the WHO classification of CNS tumors based on histological signs, pineocytoma belongs to grade I tumors, that is, it is a slowly growing benign formation with the possibility of cure after its removal. [2]
Causes of the pineocytomas
The underlying causes of most pineal (pineal) tumors are unknown. And from the point of view of morphology, the appearance of a pineocytoma occurs due to the proliferation of the main cells of the pineal parenchyma - pinealocytes. [5]
This tumor is considered to be well differentiated and belongs to tumors of neuroectodermal tissue; consists of small, cytologically benign mature cells, similar to pinealocytes (located in the form of pineocytomatous pseudo-sockets).
Since the pineal gland produces the hormone melatonin, which regulates the body's day and night cycle (circadian rhythms), and functions as a neuroendocrine organ, the main function of pinealocytes is secretory. And experts have put forward a version of the neuroendocrine etiology of tumor cells of pineocytoma. [6]
After all, pinealocytes are modified nerve cells: they have more mitochondria than ordinary neurons, and during the day the activity of these cell organelles changes cyclically. [7]
Risk factors
Potential risk factors include exposure to ionizing radiation or toxic substances, although many researchers are leaning towards a genetic etiology for this type of pineal tumor. And there is a lot of evidence for this. [8]
Pathogenesis
Most likely, the pathogenesis of pineocytoma of the pineal gland is associated with disturbances in intracellular processes, which can be caused by chromosomal rearrangements and changes in the expression of some genes:
- located on the short arms of the X and Y chromosomes of the ASMT gene, which encodes acetylserotonin-O-methyltransferase, an enzyme of the pineal gland that catalyzes the final stage of melatonin biosynthesis;
- expressed in the retina and pineal gland SAG gene, which encodes a highly antigenic protein S-arrestin;
- located on the short arm of the X chromosome, the SYP gene encoding synaptophysin, an integral membrane glycoprotein of endocrine cells, which is activated in all tumors of neuroendocrine origin;
- the S100B gene, which encodes the cytoplasmic and nuclear S100 proteins involved in cell differentiation and regulation of the cell cycle. [9]
Symptoms of the pineocytomas
The beginning of the formation of a pineocytoma is asymptomatic, and its first signs in patients are manifested by attacks of headache and dizziness, as well as nausea and vomiting.
As the neoplasm grows, other symptoms appear:
- diplopia (double vision), problems with focusing, lack of reaction of the pupils to light and impaired eye movement up and down - Parino syndrome , which develops due to compression of the tectum (plate of the quadruple) in the dorsal part of the midbrain (at the level of the superior tubercle and III cranial nerve);
- involuntary rapid eye movements with retraction of the eyelids (convergent retraction nystagmus);
- hand tremors and decreased muscle tone;
- vestibulo-atactic syndrome - a violation of gait and coordination.
Complications and consequences
The main complications and consequences are also due to the gradual increase in the size of the neoplasm.
Pineocytoma can compress the aqueduct of the midbrain (aqueductus cerebri), disrupting the circulation of cerebrospinal fluid with an increase in its pressure and the development of hydrocephalic syndrome . Increased intracranial pressure can lead to seizures and be life-threatening.
If the tumor touches the thalamus, there may be one-sided weakness (hemiparesis) and loss of sensation; when the pineocytoma acts on the hypothalamus, the control of temperature, water regulation, and sleep is impaired.
Endocrine insufficiency of the pineal gland leads to insomnia, and when the tumor formed in childhood, there may be growth retardation, premature puberty, changes in body weight, and the development of diabetes insipidus. [10]
Diagnostics of the pineocytomas
Given the fact that tumor symptoms are nonspecific, clinical diagnosis can only be based on tests, in particular, analysis of cerebrospinal fluid , biopsy and imaging techniques. [11]
Thus, instrumental diagnostics is carried out using magnetic resonance imaging (MRI) of the brain and the entire spine with contrast enhancement; ultrasound encephalography, brain angiography and ventriculography. [12]
Differential diagnosis
Differential diagnosis includes pineal cyst and malignant pineoblastoma, papillary tumor of the pineal gland, germinoma, embryonic carcinoma, choriocarcinoma, paraepiphyseal meningioma or cavernous, teratoma and pineal astrocytoma.
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Treatment of the pineocytomas
In the case of pineocytoma of the pineal gland, surgical treatment is performed by removing it. [13]
Prevention
Since pineocytoma is a benign tumor, the prognosis after surgery is favorable: the five-year survival rate after its total removal is 86-100%.