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a 43-year - old woman was admitted with sudden headache associated with nausea and vomiting .
1a ) showed a well - defined , dense , calcified mass , combined with intraventricular hemorrhage in the trigone of the right lateral ventricle , and another dense calcified mass was present in the trigone of the left lateral ventricle .
on t1-weighted mr images ( figs . 1b and 1c ) obtained on the same day , the mass in the right lateral ventricle was seen as almost iso intense relative to the brain , and after the infusion of contrast material , intense enhancement was observed .
the mass in the left lateral ventricle demonstrated inhomogeneous signal intensity on t1-weighted images , with less intense enhancement , and there was intraventricular hemorrhaging .
1d ) , the right lateral ventricular mass demonstrated inhomogeneous low signal intensity and the left lateral ventricular mass also showed low signal intensity .
the right lateral ventricular tumor was fed by both the right anterior and right posterior lateral choroidal arteries ; the predominant source of vascular supply was the former .
surgery revealed that the mass within the right lateral ventricle was hard and yellowish , and adhered to the choroid plexus .
histologic examination demonstrated the presence of psammomatous meningioma in which increased vascularity and intratumoral hemorrhage were at varying stages .
serial follow - up ct scans showed the complete disappearance of the right ventricular tumor and gradual resolution of the intraventricular hemorrhage , though the left lateral ventricular mass , also identified as a meningioma , remained .
meningioma is the most common intraventricular tumor of the trigone to occur in adults , and intraventricular meningiomas constitute approximately 0.5% to 2% of all intracranial meningiomas .
most meningiomas of the lateral ventricles originate in the trigones of these chambers , extending into their bodies ( 3 - 7 ) ; they rarly arise in the foramen of monro ( 2 , 4 , 6 ) . as a rule
although they may occur over a wide age range , intraventricular meningiomas are most common over the age of 30 years ( 3 , 6 ) , and the left lateral ventricle is more often affected than the right ( 6 , 8) .
the origin of intraventricular meningiomas is uncertain , though they appear to arise either from the stroma of the choroid plexus or from arachnoid tissue rests within the choroid , which can explain their frequent occurrence in the trigone .
their ct appearances are similar to those of meningiomas elsewhere . in most cases , they appear as well - defined mass lesions that show marked enhancement after the injection of intravenous contrast material , and calcification is seen in as many as 50% of cases . on t1- and
t2-weighted mr images , the lesions are usually isointense to normal brain parenchyma , though their signal intensity may be markedly reduced in the presence of calcification .
an obstructing atrial lesion may cause enlargement of the ipsilateral temporal horn ( 2 , 5 , 7 ) .
cerebral angiography reveals moderate to marked homogeneous blush , most frequently from the anterior choroidal artery and less commonly from the posterior lateral choroidal artery ( 5 ) .
meningiomas causing intracranial hemorrhage are infrequent , and hemorrhage from a lateral ventricular meningioma seems to be even rarer ( 3 , 4 , 8) . to our knowledge , only five cases in which a lateral ventricular meningioma presented with hemorrhage have been described ( 4 ) , and the patients involved were younger than most with meningioma .
fibroblastic meningioma is the most frequent histologic variation to occur in lateral ventricular meningiomas with hemorrhage .
the mechanism of hemorrhage in intraventricular meningioma is still uncertain but may be similar to that occurring in other hemorrhagic neoplasms , in which endothelial obliteration leads to necrosis of the vascular wall and pathologic vascular proliferation results in the formation of thin - walled vessels which rupture easily .
the events contributing to hemorrhage of meningiomas may be as follows : 1 ) the sudden disruption of congested , tortuous vessels which surround the meningioma and are less resistant to blood pressure changes ; 2 ) the rupture of new vessels with thin , softened vascular walls located in the peritumoral zone ; 3 ) bleeding from enlarged and weakened feeding arteries , a phenomenon corresponding to a demand for increased blood supply ; and 4 ) anticoagulation therapy or systemic disorders such as hypertension or atherosclerosis .
hemorrhage from a lateral ventricular meningioma does not usually require decompression such as ventricular drainage or shunt emplacement to relieve obstructive hydrocephalus , suggesting that such hemorrhages may be of venous origin , which is insufficient to obstruct csf flow .
hemorrhage from a clinically silent meningioma can influence prognosis , and surgery is thus the optimal treatment for this rare disease ( 4 ) .
differential diagnosis must include metastatic deposits in the choroid plexus which may also cause hemorrhage , though it is unusual for metastases to become so large before presentation .
ventricular hemorrhage is a recognized complication of choroid plexus papillomas , which at imaging may be indistinguishable from meningioma .
choroid plexus tumors are rare after adolescence , and in most cases a patient 's age permits clear distinction ( 2 , 3 ) .
primary gliomas may arise in the ventricles , though have not been associated with hemorrhage , and are more commonly found in the body of the ventricle .
ependymomas are much more common in the ventricular body , are rarely calcified , and have not been associated with hemorrhage .
cavernous hemangiomas , neurocytomas and hemangioblastomas are uncommon intraventricular tumors that may present with hemorrhage , and should also be included in the differential diagnosis ( 3 ) .
meningiomas causing intracranial hemorrhage are rare , and hemorrhage from a lateral ventricular meningioma seems to be even rarer . 
 we report a case of trigonal meningioma in a 43-year - old woman who presented with intraventricular hemorrhage , and describe the ct , mri and angiographic findings .