mercoledì 16 aprile 2008
Choroid plexus carcinoma
Figure 1: Axial T2 WI shows a large, heterogeneous, lobulated, frond-like lesion within the left lateral ventricle with a prominent flow void suggestive of a vessel within the lesion. There is diffuse dilatation of the ventricular system.
Figure 2: Axial T2 weighted image demonstrates another heterogeneous lesion in the right Foramen of Luschka.
Figure 3 and Figure 4 : Axial and coronal T1 fat suppressed post gadolinium MR images demonstrate heterogeneous enhancement within the mass lesions with diffuse leptomeningeal enhancement in the interpeduncular and perimesencephalic cisterns. Parenchymal invasion is also seen with enhancing foci in the left occipital region.
Figure 5: Axial T1 fat suppressed post gadolinium MR image through the abdomen demonstrates circumferential leptomeningeal enhancement around the cord.
Diagnosis: Choroid plexus carcinoma
The choroid plexus is the neuroepithelial tissue responsible for the production of CSF within the cerebral ventricular system. Neoplasms of the choroid plexus are uncommon tumors which can form anywhere there is choroid in the ventricular system. These tumors occur in proportion to the amount of normally present choroid tissue. The lateral ventricle is the most common site (50% of cases), followed by the fourth ventricle (40%) and the third ventricle (5%). About 5% of choroid plexus tumors arise in more than one location.
Choroid plexus tumors usually present in the first decade of life. Most choroid plexus tumors (about 80%) occur as the benign, slowly growing papilloma, a WHO grade I tumor with a favorable overall prognosis. The malignant variant manifests as a much more biologically aggressive WHO grade III tumor, and is far more common in children than adults.
Clinical presentation is usually due to increased intracranial pressure and hydrocephalus, due mainly to CSF overproduction, but mechanical obstruction and impaired CSF resorption may also contribute.
Choroid plexus papillomas usually present as lobulated intraventricular masses with intense, homogeneous enhancement in a child. These tumors are soft, well-circumscribed cauliflower-like masses with prominent lobulations peripherally. The mass can be hyperattenuating on CT with calcification seen in 25%. Necrosis resulting in heterogeneity and parenchymal invasion are characteristic features for choroid plexus carcinoma. Extension from one ventricle to another or into the cerebellopontine angle is a characteristic feature. The presence of focal neurological signs also suggests choroid plexus carcinoma due to parenchymal invasion. CSF seeding can be seen with both papilloma and carcinomas and enhanced MRI of the entire neuraxis is recommended prior to surgery to evaluate extent of disease.