Central Nervous System Tumors in Children
Brain tumors are the second most common form of childhood malignancy after leukemia and account for 20% of all cancers, and are the most common form of solid tumors in childhood. The incidence is 30/1,000,000 per year.
CNS tumors can be classified based on their anatomical distribution or based on their histological characteristics, depending on the basic cell of origin, according to the World Health Organization (WHO) Classification. Primary tumors are more common in children, while metastatic tumors are more common in adults. Anatomically, subscapular tumors are most common (52%), followed by suprascapular tumors (40%) and spinal tumors are rarer (5%).
Regarding the etiology of CNS tumors, no specific environmental factors have been implicated, but some studies have suggested a negative effect from ionizing radiation and maternal exposure to kerosene and food products containing nitrous substances, such as beer and certain meats. In the last decade, research has focused on genetic abnormalities that have been observed in brain tumors.
Chromosomal abnormalities that have been identified concern chromosomes 17, 22, 10 and mutations in the P53 gene. CNS tumors can occur in the context of one of the phacoemulsifications (neurofibromatosis types 1 and 2), tuberous sclerosis and Von Hippel Lindau syndrome.
Clinical symptoms
Brain tumors present with symptoms caused either by increased intracranial pressure or associated hydrocephalus or by the effect of the tumor on surrounding brain structures. This effect can take the form of neurological deficit, such as hemiparesis – monoparesis, visual field scotoma, endocrinopathy or epilepsy. Spinal cord tumors can cause kyphosis or scoliosis, which can be the only symptoms initially, while as they progress they cause sensory and motor deficits in the upper and lower extremities up to tetraparesis.
Malignant tumors have a short duration of symptoms (weeks), while benign tumors may last up to several months. Headache is a symptom that is usually described by older children. Children in the first 3-4 years of life cannot describe a headache, but try to attract attention in other ways, such as repetitive movements – banging the head, pulling hair or ears, etc.
In even younger children, intracranial hypertension can manifest as nervousness, irritability, loss of appetite and a general loss of interest in games. Other findings are swelling of the optic disc (in 40-60% of children) and paralysis of the sixth cerebral conjunctiva (in 20% of children with hemispheric tumors) and manifests as new strabismus.
Children with posterior fossa tumors often present with vomiting and gait instability as prominent symptoms.
Diagnostic studies
The diagnosis of the diseases is made using computed tomography and magnetic resonance imaging, which in recent years have been accessible to most of the population. While magnetic spectroscopy can also provide additional useful information.
Treatment
The aim of treatment is to improve symptoms and achieve long and good quality survival. Usually complete surgical excision creates the conditions for cure or optimization of survival.
In the last 20 years, surgical techniques for removing brain tumors in children have significantly improved. The use of the surgical microscope, the endoscope, the ultrasonic aspirator, stereotaxy and neuronavigation played an important role in this.
Treatment includes total or partial resection as the first stage, followed by the use of chemotherapy, radiotherapy, a combination of these or even simple monitoring depending on the histological examination.
Histologically benign tumors have a 5-year survival of 70-90% depending on the anatomical location. Histologically malignant tumors have a 5-year survival of 30-70% depending on the histological type and anatomical location. Some tumors are completely curable (e.g. pilocytic astrocytoma of the parencephalon, germinoma).
