A 31-year-old female with new-onset generalized tonic-clonic seizures has an intracranial mass detected on head CT scan. Biopsy of the mass reveals neoplastic cells that stain positive for synaptophysin and negative for glial fibrillary acidic protein. These neoplastic cells most likely originate from the same precursor tissue as which of the following?

Question

A 31-year-old female with new-onset generalized tonic-clonic seizures has an intracranial mass detected on head CT scan.  Biopsy of the mass reveals neoplastic cells that stain positive for synaptophysin and negative for glial fibrillary acidic protein.  These neoplastic cells most likely originate from the same precursor tissue as which of the following?

Quizplus · Accepted Answer

Synaptophysin is a transmembrane glycoprotein found in the presynaptic vesicles of neurons, neuroectodermal and neuroendocrine cells. Immunoreactivity of a CNS tumor for synaptophysin indicates a neuronal origin (Choice E). Such neoplasms are rare and compose less than 1% of CNS tumors. The majority of primary CNS tumors in adults are of glial origin, meningiomas and pituitary adenomas are the next most common. Primary tumors in adults tend to be supratentorial while those in children tend to lie below the tentorium. Metastatic disease to the CNS occurs more commonly than primary CNS tumors. Unlike tumors of neuronal origin, gliomas stain positively for glial fibrillary acidic protein (GFAP). Immunoreactivity for GFAP is characteristic for astrocytomas including glioblastoma multiforme, oligodendrogliomas, ependymomas and peripheral neural sheath tumors. (Choices A, B and C) Astrocytes, oligodendrocytes, and ependymal cells give rise to tumors collectively referred to as gliomas (astrocytomas, oligodendrogliomas and ependymomas, respectively). Cells from tumors of glial origin stain positively for glial fibrillary acidic protein (GFAP). (Choice D) Cells of the arachnoid villi give rise to meningiomas, most of which are benign. These tumors are diagnosed by imaging; they do not stain for GFAP or synaptophysin. Educational Objective: Synaptophysin is a protein found in the presynaptic vesicles of neurons, neuroendocrine and neuroectodermal cells. CNS tumors of neuronal origin frequently stain positively for synaptophysin on immunohistology. Neoplasms of glial origin (astrocytomas, ependymomas, and oligodendrogliomas) stain for GFAP.

A 31-Year-Old Female with New-Onset Generalized Tonic-Clonic Seizures Has an Intracranial