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Clinical presentation, diagnosis, and risk stratification of medulloblastoma

Author
Scott L Pomeroy, MD, PhD
Section Editors
Jay S Loeffler, MD
Patrick Y Wen, MD
Amar Gajjar, MD
Deputy Editor
April F Eichler, MD, MPH

INTRODUCTION

Medulloblastomas are the most common malignant brain tumor of childhood and occur exclusively in the cerebellum. The disease is rare after the fourth decade of life.

The epidemiology, clinical presentation, diagnosis, and risk stratification of medulloblastoma in children and adults will be discussed here. The histopathology, molecular pathogenesis, treatment, prognosis, and delayed complications in survivors are discussed separately. (See "Histopathology and molecular pathogenesis of medulloblastoma" and "Treatment and prognosis of medulloblastoma".)

EPIDEMIOLOGY

Approximately 500 children are diagnosed with a medulloblastoma each year in the United States [1,2]. Medulloblastoma is the most common malignant brain tumor of childhood, accounting for approximately 20 percent of all primary tumors of the central nervous system among children less than 19 years of age. The peak incidence is between five and nine years of age. Approximately 70 percent of patients are diagnosed before the age of 20. There is a slight increase in incidence between the ages of 20 to 24 years, and the disease is rare after the fourth decade, consistent with its embryonal origin.

Approximately 2 to 5 percent of medulloblastomas occur in association with either the nevoid basal cell carcinoma syndrome (NBCCS), caused by germline mutations in the patched-1 (PTCH1) gene, or familial adenomatous polyposis (FAP), caused by inactivating mutations in the adenomatous polyposis coli (APC) gene. Mutations in these genes predispose to the development of medulloblastoma through defects in pathways important in the pathogenesis of both sporadic and inherited tumors. (See "Histopathology and molecular pathogenesis of medulloblastoma", section on 'Genetic predisposition'.)

CLINICAL FEATURES

Patients with medulloblastoma present with a combination of signs and symptoms of increased intracranial pressure and cerebellar dysfunction evolving over a period of weeks to a few months. Magnetic resonance imaging (MRI) typically demonstrates a midline or paramedian cerebellar mass that enhances after contrast administration, and approximately one third of patients will have evidence of tumor dissemination through the subarachnoid space either by imaging or cerebrospinal fluid (CSF) examination.

             

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Literature review current through: Nov 2016. | This topic last updated: Tue Jul 07 00:00:00 GMT+00:00 2015.
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