Skip to Main Content

++

Neurooncology

++
++
++

What is the most likely diagnosis of a well-circumscribed lobulated mass displacing the brain that, on microscopic examination, exhibits perivascular pseudorosettes?

++
++
++

(A) Oligodendroglioma

++
++

(B) Pilocytic astrocytoma

++
++

(C) Fibrillary astrocytoma

++
++

(D) Germ cell tumor

++
++

(E) Ependymoma

++
++

(E) Ependymomas arise throughout the neuraxis, often in an intraventricular location. In the adult population, 64.1% of ependymomas are in the spinal cord, 11.8% are supratentorial, and 24.1% are infratentorial. Among the pediatric population, ependymomas are the third most common intracranial tumors after pilocytic astrocytomas and primitive neurectodermal tumors. About 30% of them appear before the age of 3 years and about 50% before the age of 5 years. Nearly 90% of pediatric ependymomas are intracranial and only 10% are intraspinal. Approximately, two thirds of intracranial ependymomas in children occur in the infratentorial compartment. Classic ependymomas grow as demarcated soft, gray masses that arise in the ventricular system. In the posterior fossa, they may fill the fourth ventricle and pass through its exit foramina. On microscopic examination, ependymomas are generally composed of uniform cells with indistinct cytoplasmic borders and round or oval nuclei. The nuclear/cytoplasmic ratio varies; it is usually high, but infrequent nodules of densely packed cells may be scattered throughout paucicellular areas. The pseudorosette is a perivascular anuclear zone of radial fibrillary processes that taper toward a vessel and is a hallmark of ependymomas. Less commonly, ependymomas show the characteristic epithelial features of true ependymal pseudorosettes. (Parisi, 6–8; McGuire, 725–729)

++
++
++

Ependymomas have

++
++
++

(A) a greater incidence among males than among females

++
++

(B) a predominant supratentorial location in the adult population

++
++

(C) thoracic predominance when located in the spinal cord

++
++

(D) an association with neurofibromatosis type II when there is multifocal spinal cord involvement

++
++

(E) a peak incidence at the age of 23 years

++
++

(D) Most ependymomas occur in childhood, with a peak incidence between 1 and 5 years. Males and females are nearly equally affected. In the adult population, infratentorial ependymomas are more common that supratentorial ependymomas. Ependymomas represent 60% of intramedullary gliomas of the spinal cord, most arising in the filum terminale (as myxopapillary variants) and occurring primarily in adults. Multifocal spinal cord ependymomas are associated with neurofibromatosis type II. (Parisi, 6–8; McGuire, 725–729)

++
++
++

Myxopapillary ependymomas occur most frequently in the

++
++
++

(A) fourth ventricle

++
++

(B) third ventricle

...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.