A previously healthy 16-year-old boy is evaluated for progressive headaches and blurred vision that started several months ago. The headaches are more severe upon waking up in the morning and are often accompanied by nausea and vomiting. He takes no medications and does not use tobacco, alcohol, or illicit drugs. Physical examination is notable for bilateral papilledema. MRI of the brain is shown in the exhibit. This patient's brain lesion most likely originated from which of the following cells?

Question

A previously healthy 16-year-old boy is evaluated for progressive headaches and blurred vision that started several months ago.  The headaches are more severe upon waking up in the morning and are often accompanied by nausea and vomiting.  He takes no medications and does not use tobacco, alcohol, or illicit drugs.  Physical examination is notable for bilateral papilledema.  MRI of the brain is shown in the exhibit.  This patient's brain lesion most likely originated from which of the following cells?

Quizplus · Accepted Answer

11ec160b_39b0_28f6_9249_67b710350644_MD0001_00 This patient with progressive headaches has an enhancing ventricular mass on MRI, consistent with a ventricular ependymoma. Ependymomas arise from ependymal cells, which line the walls of the ventricular system and the central canal of the spinal cord and produce cerebrospinal fluid. Choroid plexus tumors (derived from modified ependymal cells) can also be found in the lateral ventricles and have a similar appearance on MRI. Intraventricular tumors can cause obstructive (noncommunicating) hydrocephalus due to impaired flow of cerebrospinal fluid through the interventricular foramina. Hydrocephalus typically manifests with headache, signs of increased intracranial pressure (eg, nausea, papilledema, blurred vision), and dilated ventricles on neuroimaging. The diagnosis of ependymoma can be confirmed on histopathologic examination, which shows perivascular pseudorosettes. (Choice A) Astrocytes are the most prevalent type of glial cell in the CNS. Tumors derived from these cells (eg, astrocytoma, glioblastoma) can cause hydrocephalus due to mass effect but are typically found in the brain parenchyma as opposed to the ventricular system. (Choice C) Microglial cells are the phagocytic cells in the CNS. They are not the originators of any major types of CNS tumors. (Choice D) Brain tumors that arise from neuronal cells are rare, usually found in the brain parenchyma, and more likely to be of mixed neuronal-glial cell origin. (Choice E) Oligodendrocytes are glial cells that are responsible for the myelination of axons in the CNS. Well-differentiated brain tumors arising from oligodendrocytes are referred to as oligodendrogliomas. These tumors, like astrocytomas, occur in the brain parenchyma and not in the ventricular system. (Choice F) Schwann cells form myelin in the peripheral nervous system and serve as the cell of origin for schwannomas, which most commonly occur on upper extremity nerves. Schwannomas that arise from cranial nerves (eg, CN VIII, acoustic neuromas) can cause hydrocephalus from mass effect due to their central location but would not be associated with an intraventricular mass. (Choice G) Hemangioblastomas originate from vascular endothelial cells in the cerebellum or spinal cord. They characteristically appear as an enhancing nodule with a cystic component. These tumors often bleed, which can cause hydrocephalus due to dysfunction in cerebrospinal reabsorption at the arachnoid villi, but they do not originate from the ventricular wall. Educational objective: Ependymomas originate from the ependymal cells that line the ventricular system and the central canal of the spinal cord. Ventricular ependymomas can block the flow of cerebrospinal fluid through the interventricular foramina, causing signs of increased intracranial pressure (eg, headache, papilledema) due to obstructive (noncommunicating) hydrocephalus.

A Previously Healthy 16-Year-Old Boy Is Evaluated for Progressive Headaches