Pineocytoma is a benign neoplasm of the pineal gland (epiphysis), developing from the glandular cells of the parenchyma. Clinically manifested by symptoms of occlusive hydrocephalus, gaze paresis, strabismus, convergence disorder. In 50% of cases, cerebellar syndrome is observed. Pineocytoma is detected by clinical data, neuroimaging results (cerebral MRI, CT), analysis of cerebrospinal fluid, histological examination. The most effective treatment is radical neurosurgical resection, according to indications supplemented with a liquorosunting operation.
General information
Parenchymal tumors of the pineal gland are called pinealomas. They make up less than 1% of CNS neoplasms, include benign (pineocytoma) and malignant (pineoblastoma) formations. By specialists in the field of neurology and neurosurgery, a pineocytoma is often referred to by the term “benign pinealoma”. Neoplasia has a neuroectodermal origin, it arises from glandular tissue cells (pineacytes) that secrete melatonin, the main regulator of sleep-wake biorhythms. Pineocytoma occurs in 40% of pineal cases, mainly young and middle-aged people get sick (the peak incidence is 25-35 years old). The tumor is widespread everywhere, has the same occurrence among men and women.
Causes
The etiology of benign pinealoma is not precisely defined. Polyetiology of the disease is assumed, including the participation of hereditary factors, exogenous influences, triggers that provoke the onset of tumor growth. The most likely etiofactors of the occurrence of the disease are:
- Unfavorable environment. Radiation, toxic substances contained in exhaust gases, emissions of certain chemical industries, food preservatives, etc. have an oncogenic effect. The effect of these factors damages the cellular genome, the properties of cells change, their excessive division begins with the development of tumor formation.
- Hereditary predisposition. In the case of pineocytoma, there is no direct hereditary relationship. Researchers suggest the realization of genetic determinism as a greater probability of the occurrence of neoplasms under the same living conditions.
- Disorders of intrauterine development. Adverse effects on the fetus in the antenatal period (hypoxia, intrauterine infections, alcohol, smoking of a pregnant woman) can cause the failure of individual developmental processes with the formation of atypical cells. A child is born and grows up healthy. Subsequently, the effect of provoking triggers may cause the activation of atypical pineocytes, which give rise to the tumor process.
- Traumatic brain injury. It is not the direct cause of the disease. It is capable of provoking the growth of pineocytoma in the presence of latent atypical cells in the epiphysis, resulting from changes in the genome, deviations in the process of antenatal development.
Pathogenesis
The above-mentioned etiofactors cause the transformation of normal pineocytes into tumor cells prone to constant division. Pineocytoma is characterized by slow steady growth. The place of its localization (epiphysis) is located between the hemispheres of the brain behind the third ventricle near the Sylvian aqueduct, which provides the outflow of cerebrospinal fluid (CSF) from the third ventricle to the fourth. Considering the size of the pineal gland (on average 1 cm in diameter), it is obvious that even a small pineocytoma makes changes in the anatomical interposition of the surrounding epiphysis of cerebral structures.
First of all, the Sylvian water supply is squeezed, the cerebrospinal fluid circulation is difficult and periodically blocked. The result is an accumulation of cerebrospinal fluid in the ventricular system above the blocking site — the development of occlusive hydrocephalus, which causes the main symptoms of the tumor. In the process of growth, the pineocytoma squeezes the upper mounds of the midbrain — the subcortical centers of the visual analyzer, which causes the appearance of visual disturbances. Upon reaching a significant size, the neoplasm exerts pressure on the cerebellar tissues, provoking cerebellar symptoms.
Macroscopically, the pineocytoma is a gray-red node of lobular structure, closely soldered to the soft meninges. When microscopically examined, tumor cells have a structure similar to mature pineocytes, equipped with appendages. A pineocytoma is distinguished by the presence of pineocytic rosettes — clusters of cellular processes that look like nuclear-free fibrous zones.
Symptoms
The clinical picture is dominated by the symptoms of intracranial hypertension: persistent cephalgia, nausea, vomiting. Over time, patients note the lack of effect of medications taken from headaches, an almost constant feeling of nausea, unrelated to nutrition, and frequent vomiting that bring short-term relief. Typically, the addition of visual disorders: upward gaze paresis (Parino syndrome), strabismus, diplopia, convergence disorder, drooping of the upper eyelid. The symptoms are bilateral in nature. In half of the cases, cerebellar ataxia is observed: unsteadiness of walking, nystagmus, discoordination, hypermetry of movements, intermittent speech (dysarthria), intentional tremor. In a number of patients, pineocytoma proceeds with epileptic paroxysms. Hypersomnia may develop, and premature puberty may occur in children.
Complications
Occlusive hydrocephalus is accompanied by cerebrospinal hypertension crises caused by a transient almost complete blockage of the cerebrospinal fluid outflow. Crises are characterized by severe cephalgia, repeated vomiting, and a disorder of consciousness. Complete occlusion of the Sylvian aqueduct is characterized by a rapid increase in intracranial hypertension, compression of the brain, dislocation syndrome. As a result, compression of the cerebral trunk occurs. Dysfunction of vital centers of respiration and cardiac activity localized in the medulla oblongata leads to the death of the patient. A formidable complication is pineocytoma malignancy. With malignant transformation, there is an intensive invasive tumor growth, the formation of metastases.
Diagnostics
Anamnesis of the disease (gradual onset, steady progression), clinical data (signs of occlusive hydrocephalus, oculomotor disorders in neurological status) allow the neurologist to assume the presence of a voluminous formation in the pineal region. In order to clarify the diagnosis, the following additional studies are prescribed:
- Consultation of an ophthalmologist. It is necessary for the assessment of visual acuity, perimetry, ophthalmoscopy. There is a moderate decrease in visual function mainly due to diplopia. Visual fields are preserved. Ophthalmoscopy determines bilateral edema of the optic nerve discs, indicating severe intracranial hypertension.
- Neuroimaging. CT, MRI of the brain visualize a neoplasm of pineal localization, reveal occlusion by a tumor of the Sylvian aqueduct, hydrocephalus. The pineocytoma is characterized by clear contours, when contrasting — by an intense homogeneous accumulation of contrast agent. The absence of the possibility of tomographic studies is an indication for echoencephalography, which allows to determine the volume formation by the displacement of the middle echo signal.
- Examination of cerebrospinal fluid. The material is taken by liquor puncture. A contraindication to the study is severe hydrocephalus with the threat of dislocation. The analysis of the cerebrospinal fluid confirms the increased content of protein, cellular elements (cytosis). The absence of an inflammatory reaction makes it possible to exclude a brain abscess and other infectious lesions. The detection of tumor cells indicates the malignant nature of the pinealoma.
- Biopsy of the neoplasm. In most cases, tumor tissue is obtained intraoperatively, and stereotactic biopsy is performed in complex diagnostic situations. Histological examination makes it possible to accurately verify the type of neoplasm.
- Electroencephalography. It acts as an auxiliary diagnostic method in the case of the presence of epiprimes. Diagnoses an epileptogenic focus against the background of nonspecific diffuse changes in bioelectric activity.
Pineocytoma needs to be differentiated from other tumors of the epiphysis (hermine, pineoblast), cerebral cysts, abscesses, intracerebral hematomas, parasitic lesions. It is impossible to distinguish these formations based only on clinical data. The diagnosis of “pineocytoma” requires neuroimaging and histological confirmation.
Treatment
The standard treatment for benign pinealoma is neurosurgical removal. The operation is performed by a neurosurgeon by craniotomy followed by infratentorial supracerebellar access. If it is necessary to prevent postoperative hydrocephalus, tumor removal is supplemented with bypass surgery, ventriculocysternostomy of the III ventricle. If the pineocytoma has a small size, the issue of radiosurgical removal is considered. Neoplasia tissues obtained during surgery are subjected to immediate histological analysis. Detection of intermediate differentiation of neoplasm, malignancy processes serves as an indication for postoperative radiation and chemotherapy.
Neurosurgical treatment is accompanied by symptomatic conservative therapy. Reduction of hydrocephalus, prevention of cerebral edema is carried out by the appointment of diuretics, injections of magnesium sulfate. Repeated vomiting is stopped by antiemetics (metoclopramide), epileptic paroxysms — by taking anticonvulsants (diazepam, carbamazepine).
Prognosis and prevention
Radical resection of the neoplasm gives the patient a chance to get rid of the disease forever. With incomplete removal, the remaining tumor cells after surgery can become a source of relapse. Malignating pineocytoma has a serious prognosis due to the development of implantation metastases. Specific prevention has not been developed, since the etiopathogenetic mechanisms of pineocytoma development remain unclear. General preventive measures include prevention of the effects of oncogenic factors: radiation, carcinogens, toxins, healthy lifestyle by expectant mothers.