intracranial hemangiopericytomas ( hpcs ) are rare central nervous system ( cns ) tumors arising from zimmermann pericytes or mesenchymal cells .
it is often difficult to distinguish these tumors from meningiomas based on clinical features and radiological findings .
however , detailed research has indicated that they are more similar to the peripheral soft tissue tumors .
the first documented case of primary intracranial hpc was reported by begg and garret in 1954 . since then
, case studies have revealed that hpcs are more aggressive than meningiomas and have high rates of recurrence and distant metastasis , with local recurrence rates approaching 91% and a 15-year risk of distant metastasis of 70% after surgery alone .
although hpcs were thought to originate from pericytes in the intracranial compartment , they were usually found as dural - based masses , with nondural - based intracranial hpcs being extremely rare . here , we describe a 30-year - old man who had a large occipital falcine anaplastic hpc , which was initially managed as meningioma .
a 30-year - old gentleman with no known medical illness presented with 3 months history of progressively worsening headache associated with blurring of vision .
headache was throbbing in nature , predominantly over the occipital and nape which later on progressed to be generalized .
his visual symptoms were mainly inability to focus and blurred vision with intermittent episodes of reduced visual field over the right half .
biochemical investigations were unremarkable . computed tomography ( ct ) and magnetic resonance imaging ( mri ) studies [ figures 1 and 2 ] revealed an multilobulated and heterogenous extraaxial lesion in the occipital falcine region , predominantly toward the left occipital lobe .
this lesion measured 9.0 cm ( ap )  5.5 cm ( w )  5.8 cm ( cc ) and appeared to have originated from the occipital falx cerebri , expanding bilaterally with the majority of the mass displacing the left occipital lobe .
it addition , it was observed that the lesion showed minimal perilesional edema and was compressing surrounding brain parenchyma and bilateral occipital horn ventricles .
( a ) noncontrasted computed tomography brain showing a multilobulated and isodense lesion over the occipital lobes bilaterally ( black arrow ) .
( b ) t1-weighted imaging on magnetic resonance imaging shows a well - defined irregular and lobulated mass , which appears heterogeneously isointense .
the presence of  cortical buckling  supports the diagnosis of an extraaxial cerebral lesion ( black arrow ) .
( c ) on t2-wi , a typical  sunburst  pattern is seen diverging radially into the tumor ( black arrow ) . also seen in this sequence are multiple cerebrospinal fluid clefts ( white arrow ) and areas of flow voids ( a and b ) contrasted magnetic resonance imaging studies shows vivid enhancement of the tumor . scattered areas lacking enhancement are also seen ( white arrow ) , probably due to necrosis , or hemorrhage within the tumor .
dural tail  sign and a narrow - based tumor ( black arrow ) , at the falx cerebri where the tumor is attached .
( c ) on fluid attenuation inversion recovery sequence , the mass demonstrates some areas of hyperintensity in the periventricular and perilesional area suggestive of perilesional edema ( black arrow ) a preoperative diagnosis of meningioma was considered .
the tumor appeared to be well - encapsulated , gray in color , and highly vascularized .
postoperatively , he was monitored in the intensive care unit and was eventually wean off ventilation and discharged home a week after his operation .
he was discharged home well without any new focal deficit or worsening of the previous symptoms .
the diagnosis of anaplastic hpc was confirmed through histopathological examinations [ figure 3 ] , which showed a fairly circumscribed tumor composed of closely packed with moderate pleomorphic cells interlaced with blood vessels exhibiting staghorn pattern .
these cells have round to oval nuclei , fine chromatin pattern , and prominent macronucleoli in areas .
the cytoplasm is scanty , and the cells borders are indistinct . occasional intranuclear cytoplasmic inclusion was also seen .
immunohistochemistry examination was positive for vimentin and cd34 , where else negative for epithelial membrane antigen , s-100 , cd31 , desmin , cka1 and a3 , and glial fibrillary acidic protein .
the findings were consistent with anaplastic hpc ( who grade iii ) which showed features of a high - grade lesion , such as mitosis > 5/10 hpf , areas of necrosis , moderate nuclear atypia , increased cellularity , and areas of hemorrhage .
( a ) histological section showing closely packed and moderately pleomorphic cells interlaced with blood vessels exhibiting staghorn pattern ( black arrow ) ( h and e , 10 ) .
( b ) the cells have oval to round nuclei , fine chromatin pattern , and prominent nucleoli with moderate cytoplasm and indistinct cytoplasmic border .
mitosis is also seen here ( black arrow ) ( h and e , 40 )
begg and garret first reported the intracranial occurrence of hpc and documented its origin from the meninges .
due to its distinct histomorphology , immunophenotype and biological behavior , who in 2007 , laid down clear criteria for grading meningial hpc , making it a distinct entity .
surgically , hpcs are described as well - demarcated masses attached to the dura and are associated with profuse bleeding on resection .
these are aggressive lesions that tend to occur at an earlier age than other meningeal tumors , recur with high frequency , and metastasize extracranially , predominantly to bone , lung , liver , kidney , pancreas , and adrenals .
postoperative radiation therapy and/or chemotherapy have been associated with increased survival time , regardless of the histologic subtype of hpc .
intracranial hpcs are detected at a mean age ranging from 37 to 44 years . in a pathologic series of 94 cns hpcs , mena et al .
reported a mean age at presentation of 47 years among female subjects and of 41 years among male subjects .
in contrast to meningiomas , which are more common in females , hpcs occur more often in males ; the hpc male to female ratio is approaching 2:1 . the average age of hpc onset is between 38 and 42 years , which is 10 years earlier than meningiomas .
following their series of 13 patients with cns hpc reported a mean age of 48 years , with male predominance and majority were located at the parasagittal or falx .
the location of intracranial hpcs is similar to that of meningiomas . like meningiomas and other extraaxial masses , hpcs
are dural - based and show white matter  buckling  as was seen in our case .
described the three most common sites of 164 meningiomas as sphenoid / parasellar , lateral convexity , and superior parasagittal ; no pathologic subtyping of meningioma was reported in this series .
reported that 27 of the 44 intracranial hpcs in their series were supratentorial ; the four most common sites of occurrence were parasagittal / falx , convexity , posterior fossa , and tentorial ; none occurred as purely intraparenchymal masses .
these findings and as seen in our case confirm that hpcs occur in locations similar to meningiomas .
chiechi et al . reported , approximately one - third of their hpcs showed a narrow base of dural attachment , with the remaining two - thirds showing broad - based attachment .
chiechi et al . concluded in their series that hpcs may show a narrow base of dural attachment , a feature not typically seen in meningiomas .
hpcs , such as meningiomas , are extraaxial lesions , but unlike meningiomas , they do not have tumor calcifications .
summarized their ct findings in eight cases of intracranial hpcs as follows : unenhanced ct scans showed isodense or slightly hyperdense , well - defined , sometimes nodular masses , without calcifications , and these lesions were associated with slight edema .
these hpcs were typically connected to the convexity or falx with a broad base , were often bilateral , and often showed dense , ring - shaped enhancement . retrospectively , these reports agree with some of our findings that intracranial hpcs are heterogeneous , hyperdense , dural - based lesions , and
the mass was heterogeneous , isointense with gray matter on t1-weighted images , slightly hyperintense on t2-weighted images , showed prominent internal vessel voids , and enhanced heterogeneously on contrast . retrospectively ,
our mri findings concur with these reports . in conclusion , intracranial hpcs are dural - based hypervascular masses similar to meningiomas ; however , histologically , they are not meningiomas , and they often have different ct and mri features .
intracranial hpcs are rare , extraaxial , multilobulated masses that typically occur in patients in their third and fourth decades .
although meningiomas are frequently associated with dural invasion and with the development of abnormal vessels , hpcs are more aggressive , tend to recur even after gross total resection , and occasionally have extracranial metastases . unlike meningiomas , which frequently show hyperostosis of adjacent bone and may have intratumoral calcifications on ct scans , hpcs occasionally have bone erosion and lack calcifications and hyperostosis .
meningiomas typically show a broad base of dural attachment on ct and mr studies ; therefore , if a dural - based mass has a narrow attachment , one should also consider the possibility of hpc .
unenhanced ct scans of hpcs typically show hyperdense heterogeneous tumors , and t1-weighted and t2-weighted mr images typically show heterogeneous isointense tumors .
hpcs show heterogeneous enhancement on both contrast - enhanced ct scans and mr images . due to relatively high tendency of intraoperative bleeding of hpcs and recurrence even after gross total resection , the importance of differentiation between hpcs and meningiomas can not be overemphasized .
preoperative correct diagnosis is difficult , but it is important that it should be made .
multilobulated ( mushroom appearance ) , prominent internal signal voids , relatively narrow dural attachment , and lytic destruction without calcifications are useful findings to distinguish hpcs from meningiomas .
histopathology is the gold standard for definitive diagnosis , and it is crucial to differentiate and precisely grade these tumors . in our case ,
 the rarity of hemangiopericytoma ( hpc ) and its controversial histological classification result in its frequent misdiagnosis and thus make the treatment quite challenging . 
 it is often difficult to distinguish these tumors from meningiomas based on clinical features and radiological findings . 
 this is a case report of a man , diagnosed clinically and radiologically as meningioma , which turned out to be anaplastic hpc on histological examination . a 30-year - old man presented with 3 months of progressively worsening of headache and blurring of vision 
 . clinical examination revealed the right homonymous hemianopia with reduced visual acuity and papilledema bilaterally . 
 magnetic resonance imaging revealed a multilobulated and heterogenous extraaxial lesion attached to the occipital falx . 
 it measured 9.0 cm ( ap )  5.5 cm ( w )  5.8 cm ( cc ) and expands bilaterally with major bulk on the left . 
 an occipital craniotomy followed by a subtotal tumor excision was only achieved due to profuse bleeding intraoperatively . 
 histopathology confirmed an anaplastic hpc ( who grade 3 ) . 
 the importance of differentiation between hpcs and meningiomas can not be overemphasized . 
 a preoperative correct diagnosis is difficult , but it is important that it should be made . 
 multilobulated ( mushroom appearance ) , prominent internal signal voids , relatively narrow dural attachment , and lytic destruction without calcifications are useful findings to distinguish hpcs from meningiomas . 
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