Differential diagnosis of infratentorial tumors in children

With the exception of the first year of life, infratentorial brain tumors are more frequent first decade than tumors in the supratentorial compartment. In particular these are cerebellar low-grade astrocytomas, medulloblastomas, brainstem gliomas and ependymomas of the fourth ventricle. The morphology on MRI and CT and the mode of dissemination permit differential diagnosis in many cases. To allow correct stratification into different treatments in possibly disseminating malignant brain tumors, knowledge of the status of dissemination is essential, and therefore not only cranial but also spinal MRI is indispensable for staging. If the spinal MRI is performed in the immediate postoperative period, knowledge of the normal non-specific purely postoperative changes,often seen as enhancement in the subdural spinal spaces is necessary to avoid misinterpretation as meningial seeding. The differential diagnosis of pediatric infratentorial brain tumors and the morphology of subdural enhancement are illustrated with typical images. The natural history of the most frequent tumors and its importance for treatment decisions is discussed in light of the literature.