A 7-year-old child presents with a 3-week history of morning vomiting and walking disorder . CT scan and MRI (Fig. 18.1) highlight a tumor process occupying the brainstem and compressing the 4th ventricle.

Tumors of the central nervous system (CNS) are the most common solid tumors in children according to Western cancer registries, and one of the main causes of morbidity and mortality in childhood. Advances in neuroradiology neurosurgery and radiation have significantly improved diagnosis procedures and management. CNS tumors are characterized by a high histopathology variability. Treatment takes into consideration the histopathology, the tumor site and extent, and long-term side effects of treatment, particularly with regard to the intellectual development of children.

In Africa, these tumors are rarely reported mostly because of underdiagnosis. In Uganda, for example until 2007, there were only five neurosurgeons in a country with 36 million inhabitants. With the increasing number of trained caregivers and development of the diagnostic infrastructure, and particularly with access to CT scans, these tumors should be diagnosed more frequently.

Brain tumors represent almost 20 % of childhood cancers in Western registries. Though the infratentorial location is the most frequent, in infants supratentorial tumors are more frequent.

In only 5–10 %, they are associated to a predisposing syndrome (Table 18.1). Radiotherapy is also a predisposing factor to CNS tumors.

In most cases biopsy is necessary to confirm the diagnosis. The stereotactic biopsy technique allows biopsy samples in most locations. In diffuse brain stem tumorss, some pineal tumors, and tumors of the optic tract, treatment without histological confirmation can be considered.

CNS tumors are characterized by their great diversity. Immunohistochemistry studies including glial markers (GFAP for glial fibrillary acidic protein) and neural (synaptophysin, the neurofilament protein) ensures a better classification of these tumors.

Types found at infratentorial level, are basically medulloblastoma, cerebellar astrocytoma, brain stem or ependymoma tumors, and in infants rhabdoid tumors . Supratentorial tumors are mostly heterogeneous. Low-grade gliomas represent 75 % of cases in this area. In the suprasellar region, craniopharyngioma or pathway glioma is encountered most frequently. At the pineal region, the germ cell tumor, pineoblastomas and, pineocytoma account for the most of the tumors at this location. Choroid plexus tumors are mostly seen in infants.

The clinical presentation of CNS tumors varies according to tumor site, histological nature, and the age of the child. In most cases, the combined symptoms show signs of intracranial hypertension (ICHT ) and neurological deficit. The onset of ICHT mainly is related to a deep median tumor or ventricular location causing hydrocephalus rather than to the mass effect of the tumor or peritumoral edema.

Morning headaches, vomiting, and visual disturbances form the classic symptomatic triad of ICHT. Vision disorders may include a decrease in visual acuity , diplopia , or intermittent strabismus. Eye fundoscopy may show papillary edema. Clinical manifestation may be less suggestive and include recurrent or persistent headaches, inappetence with nausea and vomiting, unexplained abdominal pain, a change in behavior, and decrease in performance at school, and rarely torticollis. In infants, the diagnosis is more difficult because of the opening of the cranial sutures and the fontanel and brain plasticity. ICHT induces macrocrania, a bulging of the fontanel and sometimes Parinaud syndrome (paralysis of the verticality of the eye giving it a “sunset” look). Sometimes this is mainly a behavioral change, decrease in playful activity, sleepiness or irritability, and less frequently is expressed by axial hypotonia, apathy, and failure to thrive.

In Africa, patients admitted to neurosurgery are often diagnosed with significant delay and in late stages. Up to 20 % of children with posterior fossa, tumors are blind reflecting long-lasting ICHT.

Other neurologic symptoms may be suggestive of the tumor site (Table 18.2).

The development of the neuroimaging techniques have had a major impact on the diagnosis and monitoring of brain tumors. A less invasive diagnosis procedure and better evaluation of locoregional extension and metastatic status are now readily available.

The CT scan (computerized tomography) is a major diagnostic tool that can detect 95 % of tumors particularly with the use of contrast. CT is superior to the MRI in evaluating tumor calcifications. However, it is less accurate in evaluating posterior fossa tumors.

An MRI (magnetic resonance imaging) non-irradiating technique is the best choice in the assessment of brain tumors. However, it is more difficult in small children and infants because of the need for prolonged immobilization and most of time general anesthesia. This procedure is more sensitive for the detection of brain tumors, particularly in temporal location and for the evaluation of the perilesionel edema. The classical appearance is in a hyposignal in T1 and hypersignal T2 and T1 after injection of Gadolinium. However MRI characteristics can vary according to the tumor type. Spinal MRI ideally should be done prior to any surgical intervention in case of an aggressive tumor to detect possible spinal metastases. In Africa, where an MRI is not available in most parts, a CT scan with CSF analysis is the best alternative in most cases.

In certain cases, the imaging study can be diagnostic and treatment may be considered without histological confirmation.

The PET scan (positron emission tomography) using 2-Deoxyglucose labeled Fluor 18 (FDG) is effective to evaluate the metabolic activity of a tumor. Astrocytomas and oligodendrogliomas are usually hypometabolic, while anaplastic astrocytoma and glioblastoma multiforme are hypermetabolic. The PET scan maybe useful: