The differential diagnosis of a CNS mass lesion includes malignant tumor, benign tumor, arteriovenous malformation, aneurysm, brain abscess, cysticercosis, granulomatous disease (tuberculosis, sarcoid), intracranial hemorrhage, pseudotumor cerebri, vasculitis, and, rarely, metastatic tumor.
The therapy for children with CNS tumors is individualized and depends on the tumor type, location, size, and associatedsymptoms. High-dose dexamethasone often is administered immediately to reduce tumor-associated edema. Surgical objectives are complete excision, if possible, and maximal debulkingif a complete excision is not possible. In children, radiationtherapy often is combined with chemotherapy; in young children, radiation therapy may be delayed or avoided altogether.Primitive neuroectodermal tumors (including medulloblastoma) and germ cell tumors are sensitive to chemotherapy; gliomas are less sensitive to chemotherapy. Chemotherapy playsan especially important role, particularly in infants in whomthe effects of high-dose CNS radiation may have devastatingeffects on growth and neurocognitive development.
Short-term adverse effects of therapy include nausea, vomiting, anorexia, fatigue, immunosuppression, and cushingoid features. Long-term adverse effects include neurocognitive deficits, endocrinologic sequelae, decreased bone growth, ototoxicity, renal insufficiency, cataracts, infertility, and second malignant neoplasms (including myelodysplasia). The neurocognitive deficits can be significant, particularly in infants and young children, and are the primary reason for the continued search for the lowest efficacious radiation therapy dose and the most conformal delivery methods for the radiation therapy boosts. Cerebellar mutism syndrome occurs in 25% of patients after resection of a posterior fossa tumor and is characterized by an acute decrease in speech (often mutism), behavioral changes (e.g., irritability, apathy, or both), diffuse cerebellar dysfunction, and other neurologic abnormalities. It may begin within hours to days of surgery and is usually self-resolving within weeks to months; cerebellar ataxia and dysmetria often persist. Somnolence syndrome, which is characterized by excessive fatigue and sleepiness, may occur in the months after completion of radiation therapy and is self-limited. Posterior fossa syndrome manifests as headache and aseptic meningitis days to weeks after surgery in this area.
Improvements in neurodiagnosis, neurosurgical techniques, chemotherapy regimens, and radiation therapy techniques
Table 157-1 Location, Incidence, and Prognosis of CNS Tumors in Children LOCATION INCIDENCE (%) 5-YEAR SURVIVAL (%)
Infratentorial (posterior fossa) 55–60 Astrocytoma (cerebellum) 20 90 Medulloblastoma 20 50–80 Glioma (brainstem) 15 High grade: 0–5; low grade: 30 Ependymoma 5 50–60 Supratentorial (cerebral 40–55 hemispheres) Astrocytoma 15 50–75 Glioblastoma multiforme 10 0–5 Ependymoma 2.5 50–75 Choroid plexus papilloma 1.5 95 Midline Craniopharyngioma 6 70–90 Pineal (germinoma) 1 65–75 Optic nerve glioma 3 90 have improved overall outcome. The 5-year overall survival rate associated with all childhood CNS tumors is approximately 50% to 60%, resulting in large measure from the high curability of cerebellar astrocytomas and the increasing cure rate for patients with medulloblastoma (Table 157-1). Intrinsic brainstem gliomas and glioblastoma multiforme have extremely poor prognoses.