Pediatric brain tumors: Pathology review

In the neurology ward, two children came in with the same symptoms: morning headaches, nausea, vomiting, and frequent falls. One of them is a 12 year old named Greg, and the other is a 14 year old individual named Suzan. Greg’s symptoms started a few months ago and retained the same level of severity, while Suzan’s symptoms started a few weeks ago and are rapidly worsening. A brain MRI with contrast is ordered for both of them, which showed a well circumscribed cystic lesion in the cerebellum for Greg, and a solid, heterogeneous mass in the cerebellum that compresses the fourth ventricle in Suzan.

Okay, so both Greg and Suzan have pediatric brain tumors. Brain tumors occur when there’s uncontrolled growth of abnormal cells within the brain. They are broadly classified into primary tumors originating from cells within the nervous system, and metastatic tumors originating from cells outside the nervous system. Primary brain tumors are the most common solid tumors in children and can be either benign or malignant. Now, for the exams, it’s important to remember that the most common primary brain tumor in both adults and children are gliomas, and more specifically, a subset of these called astrocytomas. In children, medulloblastomas and ependymomas are next on the list, while in adults gliomas are followed by meningiomas. Less common brain tumors include craniopharyngioma, pinealomas, pituitary adenomas, oligodendrogliomas, hemangioblastomas, and schwannomas. Now, metastatic tumors are much more common in adults and are always malignant. In order of decreasing frequency, they most commonly come from cancers of the lung, breast, skin melanomas, kidneys and colon.

Okay, brain tumors can also be categorized based upon their location as either supratentorial, or above the cerebellar tentorium, and infratentorial tumors, or below the tentorium, though some tumors can form in either. In children, a very high yield concept is that most brain tumors are infratentorial, whereas in adults, they are usually supratentorial, and that’s something you also have to remember for the test!