CNS Tumors in Children
Brain and central nervous system (CNS) tumors are the most common pediatric solid organ tumor and second most common malignancy overall behind leukemia.1
CNS tumors are the leading cause of cancer death in children aged 0 to 14 years.2
Associated morbidity and mortality have improved with more advanced treatment but are still significant.
The base of the skull contains 3 fossae: anterior, middle, and posterior.
The posterior fossa is the most inferior fossa and houses the cerebellum, medulla, and pons (Figure 57.1).
The cerebellum is separated from the cerebrum by the tentorium cerebelli, an extension of the dura mater.
Structures in or adjacent to the posterior fossa include the foramen magnum, jugular foramen, internal acoustic meatus, and the ventricular system distal to the third ventricle (Figure 57.2).
EPIDEMIOLOGY AND ETIOLOGY
Incidence: According to the Central Brain Tumor Registry of the United States, the estimated incidence of primary nonmalignant and malignant CNS tumors is 5.4 cases/100 000 person-years for children and adolescents ≤19 years of age.3
Males are diagnosed more frequently than females.
Incidence decreases with age, with newborns (<1 year old) diagnosed at an annual age-adjusted rate of 6.22/100 000; 1- to 4-year-olds at 5.53/100 000; and both 5- to 9-year-olds and 10- to 14-year-olds at 5/100 000.4
CNS tumors are more common in Asian/Pacific Islanders (6.05/100 000) and whites (5.46/100 000) than Hispanics (4.36/100 000) or blacks (4.12/100 000).4
Figure 57.1 Medial views of the brain. (Reprinted with permission from Agur AMR, Dalley AF. Grant’s Atlas of Anatomy. 14th ed. Philadelphia, PA: Wolters Kluwer Health; 2017.)
Etiology: The etiology of most pediatric CNS tumors is unknown.
Exposure to ionizing radiation, particularly cranial irradiation for ALL treatment, increases risk.
A minority of cases are associated with genetic conditions, such as neurofibromatosis, tuberous sclerosis, and Turcot syndrome.
Classic presentation: Symptoms depend on tumor location and patient age. They are often nonspecific and may be confused for more common childhood conditions, leading to a median delay in diagnosis of ˜3 months.5
Headaches are the most common symptom, classically presenting in the early morning and relieved by vomiting.
Tumors occupying the fourth ventricle or cerebral aqueduct are likely to cause symptoms of elevated intracranial pressure (ICP), such as headache, papilledema, nausea, or vomiting.
CNS tumors in children most commonly arise in the posterior fossa. Tumors in this region are likely to cause symptoms of increased ICP, gait abnormalities, and coordination deficits.