Topics Discussed: astrocytoma, juvenile; astrocytoma, juvenile pilocytic; brain tumor; brain tumor, childhood; craniopharyngioma, childhood; desmoplastic infantile ganglioglioma; dysembryoplastic neuroepithelial tumor; ependymoma, pediatric; ganglioglioma; glioma; glioma, brain stem, pediatric; medical oncology; medulloblastoma, childhood; neuroectodermal tumors, primitive; oligodendroglioma; pineal gland neoplasm; pineoblastoma; pineocytoma; primitive neuroectodermal tumor, supratentorial; xanthogranuloma, juvenile.
Excerpt:"Medulloblastoma is a highly aggressive form of childhood brain tumor and is the most common malignant central nervous system tumor in children. The term "medulloblastoma" is actually a misnomer, derived from the idea that these tumors arose from multipotential cells known as medulloblasts. These tumors have since been reclassified as PNETs and thus can be referred to interchangeably as PNET-MB, medulloblastoma, or infratentorial PNET. MB represents about 20% of all pediatric brain tumors and 30% of posterior fossa tumors. There is a 2 to 1 male predominance. These tumors present with a classic posterior fossa syndrome, including headache that is worse in the morning, nausea, vomiting, and a fairly rapid decline over 1 to 2 months. Occasionally presentation can be related to spinal pathology from drop metastases, including back pain, leg pain, or paraparesis. Physical examination findings include papilledema, sixth-nerve palsies, lethargy, or ataxia. The diagnostic evaluation of these lesions begins with imaging. CT can be used for emergent symptoms, but contrasted MRI is the study of choice. CT shows hyperdensity in the area of the vermis, often with speckled calcifications, ± cyst formation (Figure 25-1). MRI will show T1 iso- to hypodensity and T2 hyperintensity, as well as avid enhancement with contrast (Figures 25-2, 25-3, and 25-4). Diffusion-weighted imaging can also help differentiate these tumors from others, as it will often reveal restricted diffusion as a consequence of the lesions' hypercellularity (Figures 25-5 and 25-6)...."
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