A brain tumor or intracranial neoplasm occurs when abnormal cells form within the brain. There are two main types of tumors: malignant or cancerous tumors and benign tumors.Cancerous tumors can be divided into primary tumors that start within the brain, and secondary tumors that have spread from somewhere else, known as brain metastasis tumors. This article deals mainly with tumors that start within the brain. All types of brain tumors may produce symptoms that vary depending on the part of the brain involved
Symptoms as consequences of increased intracranial pressure often first noticed) Large tumors or tumors with extensive peritumoral swelling (edema) inevitably lead to elevated intracranial pressure which translates clinically into headaches, vomiting (with or without nausea), altered state of consciousness (somnolence, coma), dilation of the pupil on the side of the lesion (anisocoria), papilledema (prominent optic disc at the funduscopic eye examination). However, even small tumors obstructing the passage of cerebrospinal fluid (CSF) can also present such symptoms. Increased intracranial pressure may result in brain herniation (i.e. displacement) of certain parts of the brain, such as the cerebellar tonsils or the temporal uncus, resulting in lethal brainstem compression. In very young children, elevated intracranial pressure may cause an increase in the diameter of the skull and bulging of the fontanelles.
A total of 926 tumours (48%) diagnosed in children (0-14 years of age) are notified by the three main source types (paediatric centres, laboratories for pathological anatomy/clinical biology and hospitals/health insurance companies) (Figure 3). In total, 1,610 (84%) of all diagnoses are delivered by more than one source type. The remaining 303 tumours are only registered by one source type of which 83 tumours (4.3%) are notified by a paediatric centre only. These tumours mainly concern brain tumours (N=28), leukaemias (N=17) and lymphomas (N=10). Leukaemias are not expected to be reported by the pathological pathway. Another important part of these tumours are only diagnosed on clinical basis and not confirmed microscopically. The 147 diagnoses (7.7%) only received from a laboratory were submitted to an individual and thorough quality control to confirm the diagnoses. This specific control included a review of the written protocols and if necessary, the pathologist was contacted for additional information about the diagnosis. For 73 tumours (3.8%) only a registration from an oncological care program was received. Also here this mainly concerns brain tumours (N=35) and leukaemias (N=12). But, this does not automatically imply that the peadiatric centres for hematology-oncology were not involved.