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neurofibromatosis type 2 ( nf2 ) is an autosomal dominant disease characterized by schwannomas , meningiomas , and ependymomas .
bilateral vestibular schwannomas , occurring in the majority of adult patients with nf2 , are diagnostic of nf2 .
they usually present as an enhancing mass extending into the cerebellopontine cistern from the internal acoustic canal .
however , in some cases , these tumors may be absent or too small to be detected with standard computed tomography ( ct ) and/or magnetic resonance imaging ( mri ) .
in such cases , presence of the non - tumoral calcifications with or without tumoral calcifications may suggest the possible diagnosis of nf2 . in this paper , we present a case of nf2 , who was diagnosed on the basis of intracranial calcifications .
a 34-year - old man with a complaint of mild hearing loss in the left ear was referred to our department for temporal bone ct .
temporal bone ct [ figure 1a  d ] , showed subependymal calcification at the foramen of monro [ figure 1a ] , choroid plexus calcifications within the lateral ventricles [ figure 1b ] , a small calcified lesion adjacent to the right cavernous sinus [ figure 1c ] , and a partially calcified midline mass adjacent to the fourth ventricle [ figure 1d ] .
these findings were found highly suspicious for nf2 , although no prominent mass was seen within the cerebellopontine cisterns or internal acoustic canals .
cerebral mri with intravenous contrast administration showed no major findings except an enhancing mass at the posterior aspect of the fourth ventricle figure 2 .
inner ear mri with the aid of fast imaging employing steady state acquisition ( fiesta ) [ figure 3a ] and contrast enhanced t1-weighted sequences with thin slices [ figure 3b ] revealed bilateral small intracanalicular lesions consistent with schwannomas .
in addition , the small calcified lesion adjacent to the right cavernous sinus showed contrast enhancement indicating a meningioma .
spinal mri [ figure 4a and b ] , which was performed to evaluate possible additional tumors , showed a mass causing focal cord expansion at c5-c6 level [ figure 4a ] and multiple enhancing small intramedullary lesions [ figure 4b ] consistent with ependymomas in the cervical cord .
posterior fossa mass was operated and diagnosed as who grade 2 ependymoma histopathologically [ figure 5 ] .
neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
axial computed tomography ( parenchymal window ) of the temporal bone shows subependymal calcification ( arrow ) at the foramen of monro neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
axial computed tomography ( parenchymal window ) of the temporal bone shows extensive choroid plexus calcifications within both atria ( arrows ) extending into the left temporal horn ( arrowhead ) neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
axial computed tomography ( parenchymal window ) of the temporal bone reveals a small calcified lesion ( arrow ) adjacent to the right cavernous sinus neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
axial computed tomography ( parenchymal window ) of the temporal bone shows a midline mass ( arrow ) with coarse calcifications at the posterior aspect of the fourth ventricle .
note the normal appearance of bilateral pontocerebellar cisterns neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
sagittal postcontrast t1-weighted image shows an enhancing midline mass ( arrow ) within the posterior fossa .
neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
axial fast imaging employing steady state acquisition image demonstrates small intracanalicular lesions ( arrows ) obliterating the fundus of the both internal acoustic canals neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
inner ear magnetic resonance axial post - contrast t1-weighted image shows enhancement within the small tumors ( arrows ) of the both internal acoustic canals neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
cervical spinal magnetic resonance sagittal t2-weighted image shows a mass ( arrow ) causing cord expansion at c5-c6 level with cystic component and hemosiderin at caudal margin , which are typical findings of a cord ependymoma neurofibromatosis type 2 .
cervical spinal magnetic resonance sagittal postcontrast t1-weighted image shows enhancement within the mass at c5-c6 level ( arrowhead ) and additional small intramedullary tumors with the appearance of  string of pearls  ( arrows )
neurofibromatosis type 2 . a 34-year - old man with mild hearing loss in the left ear .
photomicrograph of hematoxylin and eosin stained tissue at 10 shows neoplastic ependymal cells with nuclear uniformity ( arrowhead ) and fibrillary cytoplasmic processes ( arrow ) remain attached to blood vessels , 10 )
nf2 is a hereditary syndrome characterized by the nervous system tumors including schwannoma , meningioma , and ependymoma . although sharing the same name , nf1 and nf2 are distinct disorders arising from separate chromosomes with different clinical and imaging findings [ table 1 ] .
a mutation causing the inactivation of a tumor suppressor gene on the long arm of chromosome 17 is responsible for nf1 .
however , nf2 is caused by a defect in the gene located on chromosome 22 , which normally encodes a tumor suppressor protein called  merlin . 
neurofibromas , which are hallmarks of nf1 , are seen in a minority of patients with nf2 .
therefore , the term  multiple inherited schwannomas , menengiomas , ependymomas ,  which enables a better definition of the disease is now being widely used .
genetic , clinical , and neuroimaging features of nf1 and nf2 diagnosis of nf2 depends mainly on the presence of vestibular schwannoma and/or family history .
bilateral vestibular schwannomas or unilateral vestibular schwannom ( age < 30 years ) plus a first - degree relative with nf2 are the criteria for a definite diagnosis of nf2 . in the absence of vestibular schwannoma , a first - degree relative with nf2 and any two of the lesions : meningioma , glioma , schwannoma or juvenile posterior subcapsular lenticular opacity is necessary for the definite diagnosis . in the absence of family history , presumptive diagnosis of nf2
is possible if unilateral vestibular schwannoma ( age < 30 years ) with characteristic disease features are found .
despite all these criteria , diagnosis may be problematic in patients who do not have bilateral vestibular schwannomas at the initial examination .
diagnosis is relatively easy when typical appearance of bilateral vestibular schwannomas bulging into cerebellopontine cisterns from internal acoustic canals is seen .
however , some patients , especially children and young adults , can present with schwannomas of other nerves , meningiomas , ependymomas , and ocular abnormalities .
therefore , presentation of a young patient with single / multiple schwannomas or multiple extra - axial brain or spine tumors should prompt screening for nf2 .
in such cases , initial radiological examination may be a standard ct or mri in which small intracanalicular tumors may be easily overlooked .
for this reason , axial and coronal thin slice contrast enhanced t1-weighted sequences should be performed to detect small schwannommas of vestibular or other cranial nerves . furthermore ,
steady state free precession sequences , such as fiesta or constructive interference steady state , which allow detailed evaluation of cranial nerves and precise detection of small tumors should be included in the imaging protocols .
arachnoid cyst , epidermoid cyst , meningioma , metastasis , sarcoidosis , menengitis , and aneursym should also be considered in the differential diagnosis of the cerebellopontine angle ( cpa ) lesions .
arachnoid cyst follows cerebrospinal fluid ( csf ) signal on all magnetic resonance sequences and shows no contrast enhancement .
epidermoid cyst may mimic cystic schwannoma ; however , characteristic features such as diffusion restriction and the absence of contrast enhancement suggest the diagnosis of epidermoid cyst .
hyperostosis in the adjacent bone may be a helpful finding in the diagnosis of a meningioma .
metastasis and sarcoidosis may both cause dural - based lesions and/or leptomeningeal involvement in the cpa .
metastasis is a more likely diagnosis in an older adult with known malignancy and multifocal involvement .
clinical information and csf analysis may have a key role in the diagnosis of menengitis .
pulsation artifact in the phase - encoding direction is an important clue for the diagnosis .
they may be tumoral or non - tumoral in origin . before the era of mri ,
several reports have been published regarding non - tumoral calcifications on ct in patients with nf2 .
benign calcifications were detected within choroid plexus , cerebellum , and cerebral parenchyma in 7 of 11 patients with nf2 .
unilateral or bilateral prominent vestibular schwannomas were found in all cases of these two reports .
these reports indicate that the presence of non - tumoral calcifications is a notable feature of nf2
. however , diagnostic significance of these calcifications seems to be underestimated with the increasing utilization of mri throughout the world .
subependymal calcifications are almost always associated with tuberous sclerosis ; however , similar calcifications may be seen in nf2 .
calcifications of choroid plexus are rarely seen in children and are common after the age of 40 years .
therefore , extensive choroid plexus calcifications in children and young adults may suggest the possibility of nf2 .
cortical calcifications alone may have less diagnostic importance , because many other pathologies including congenital , infectious , metabolic , vascular , tumoral , and sequel lesions can cause similar calcifications .
postmortem studies have shown glial microhamartomas in the cerebral cortex and basal ganglia of patients with nf2 .
non - tumoral calcifications may be related to these hamartomatous lesions , which do not seem to be preneoplastic .
ependymomas are neoplasms , which are commonly associated with calcifications . in patients with nf2 ,
furthermore , like in our case , a calcified ependymoma within the fourth ventricle in a nf2 patient is a very unusual finding . to our knowledge ,
the presence of multiple ependymomas in the spinal cord is a well - known feature of nf2 .
a recent study regarding nf2 showed that ependymomas had a predilection for cervical cord or cervicomedullary junction , while brain involvement was not reported in that study . in our case , diagnosis of nf2 was suspected due to the presence of choroid plexus and subependymal calcifications on ct , although standard ct and mri did not reveal any prominent mass within cerebellopontine cisterns or internal acoustic canals .
with the aid of dedicated further investigations ; bilateral small intracanalicular lesions , presumed calcified meningioma , histopathologically proven fourth ventricle ependymoma , and the intramedullary lesions consistent with ependymoma in the cervical spinal cord were detected all of which finally confirmed diagnosis of nf2 .
non - tumoral calcifications with or without tumoral calcifications may suggest the possibility of nf2 , especially in those without obvious lesions within the cerebellopontine cistern .
choroid plexus and subependymal calcifications may be the only apparent signs of nf2 when ct is the initial radiological examination .
therefore , further evaluation with proper imaging techniques for nf2 should be done in the presence of these calcifications regardless of whether or not nf2-related tumors are detected initially .
neurofibromatosis type 2 ( nf2 ) is a genetic disorder associated with schwannomas , meningiomas , and ependymomas . 
 intracranial calcifications , either tumoral or non - tumoral , are relatively lesser known features of nf2 . here , we present a case of nf2 , in which the diagnosis was suspected due to the presence of choroid plexus and subependymal calcifications , although no obvious schwannoma or meningioma was detected initially on standard computed tomography or magnetic resonance imaging . 
 this case highlights the importance of further evaluation with appropriate imaging techniques .