Tumors of the nervous system comprise a diverse, heterogeneous group of neoplastic lesions that affect every age group and every element of the central and peripheral nervous systems. The cause of most adult and pediatric central nervous system (CNS) tumors is largely unknown. A few rare genetic syndromes play a clear and independent role in brain tumor development, including neurofibromatosis types 1 and 2, Li-Fraumeni syndrome, Gardner syndrome, Turcot syndrome, and von Hippel-Lindau disease (Table 12–1). Independent of these disorders, a family history of malignant brain tumors is a minor risk factor for developing brain tumors. Most CNS tumors are thought to be sporadic in origin, as familial and genetic associations play a role in only about 5% of all cases. Nonetheless, many sporadic tumors arise as a result of combined somatic mutations that activate oncogenes such as platelet-derived growth factor and inactivate tumor suppressor genes such as p53. The role of environmental factors—physical, chemical, or infectious—in causing such mutations or otherwise acting as risk factors is unknown.
Table 12–1.Genetic syndromes and corresponding tumor types. ||Download (.pdf) Table 12–1. Genetic syndromes and corresponding tumor types.
| ||Mutation ||Tumor ||Inheritance Pattern |
|Gardner syndrome ||APC ||Colonic polyps, astrocytomas ||— |
|Li-Fraumeni syndrome ||p53 mutation ||Solid systemic cancers, astrocytomas ||Autosomal recessive |
|Multiple endocrine neoplasia types (MEN) 1 and 2 ||Chromosome 11 ||Pituitary adenomas ||— |
|Neurofibromatosis (NF) types 1 and 2 ||Chromosome 17 (NF1); chromosome 22 (NF2) ||Neurofibromas, acoustic schwannomas, meningiomas, skin lesions ||Autosomal dominant |
|Turcot syndrome ||Chromosome 5 ||Colonic polyps, astrocytomas ||Both autosomal dominant and recessive |
|von Hippel-Lindau syndrome ||Chromosome 3 ||Infratentorial and spinal cord hemangioblastomas ||Autosomal dominant |
ESSENTIALS OF DIAGNOSIS
Primary or metastatic
Typical presenting signs are headache, seizures, focal neurologic deficits, and nonspecific cognitive and personality changes that follow a subacute course
Detailed neurologic examination can localize lesions within the CNS
Imaging tests are essential to direct further diagnostic and management strategies
Surgical biopsy is almost always required for conclusive diagnosis
Primary brain tumors are neoplastic and nonneoplastic lesions that arise directly from the brain tissue and its linings. In the United States, approximately 80,000 primary brain tumors are diagnosed each year, with more than 26,000 primary malignant and 53,000 nonmalignant brain tumors. About 700,000 people in the United States are living with brain tumors, and approximately 17,000 people will die from them. A general increase in incidence over the past 20 years is most likely associated with the widespread availability of computed tomography (CT) and magnetic resonance imaging (MRI) scanning and an aging population. Meningiomas are the most common, representing 37% of all primary tumors and accounting for the meninges as the most common location for primary and CNS tumors. Gliomas, which describe tumors arising from the ...