Meningeal Hemangiopericytoma: Presentation, Diagnosis & Treatment

1. Dr. FARRUKH JAVEED

2.  Meningeal hemangiopericytoma is an
aggressive extra-axial CNS tumor that
behaves like a soft tissue sarcoma.
 It is a malignant neoplasm and has the
biologic capability to escape from the CNS
and metastasize widely.
 The originating cells are thought to be
meningeal capillary pericytes,
Zimmerman pericytes, or precursor cells
with angioblastic tendencies.
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3.  This lesion was named hemangiopericytoma by Stout and
Murray in 1942, although it was extracranial in location.
Information about this tumor comes from cases reported
variably as angioblastic meningioma within large series of
meningiomas and series devoted to meningeal
hemangiopericytomas.
 Its biologic behavior, as well as molecular and genetic profile,
suggests that this lesion may be accurately described as a
dural-based sarcoma.
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4.  The 2007WHO classification differentiates meningeal
hemangiopericytoma from meningioma and groups
hemangiopericytoma in the category of mesenchymal tumors.
 The 2013WHO classification of soft tissue and bone tumors has now
combined solitary fibrous tumors and hemangiopericytomas into one
single category of solitary fibrous tumors that is associated with a
recurrent NAB2-STAT6 gene.
 However, because of the aggressive nature of meningeal
hemangiopericytomas, there is an argument to recognize them as a
clinical entity distinct from solitary fibrous tumors, and management
must reflect their much more aggressive behavior.
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5.  Hemangiopericytomas account for less than 1% of all CNS
tumors and for about 2% to 4% of large series of meningeal
tumors.
 About 10% of meningeal hemangiopericytomas occur in
children.
 They can be misdiagnosed as meningioma.
 The average age at diagnosis is in the fifth decade.
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6.  Hemangiopericytomas are located similar to meningiomas,
with 15% in the posterior fossa and 15% in the spine.
 Of the spinal tumors, about half are in the cervical region.
 As with meningiomas, there is the occasional report of a
nonmeningeal cerebral location for this tumor.
 Primary multifocal meningeal hemangiopericytomas have not
been reported.
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7.  Grossly, meningeal hemangiopericytomas are firm and
lobulated and vary from pink-gray to red in color.
 They are extremely vascular, are often adherent to the dura,
but do not usually invade the brain.
 They do not spread en plaque and rarely contain calcification.
 The tumors are very cellular, with round to oval cells.
 The cells are arranged around thin-walled vascular spaces
lined by a nonneoplastic endothelium.These “staghorn”
capillaries are a distinguishing feature and can be quite
numerous.
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8.  Mitoses vary from one to several per high-power field.
 Microcysts, necrosis, and papillary architecture may be seen and
have been reported in up to 50% of the tumors.
 Psammoma bodies are not seen.
 Reticulin envelops individual cells (thus differentiating it from
meningioma, in which reticulin is scarcer and segregates the
tumor into lobules). 8

9.  Recurrent tumors retain their histologic features, and
metastatic hemangiopericytomas are histologically identical
to the primary tumor.
 Meningeal hemangiopericytomas are histologically and
biologically distinct from atypical or malignant meningiomas.
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10.  The most frequent initial symptom is HEADACHE or FOCAL
SIGNS related to tumor location.
 SEIZURES are initially present in only about 16% of patients
with supratentorial tumors, which is compatible with the fact
that they do not microscopically infiltrate the brain and grow
rather rapidly.
 INTRACRANIAL HEMORRHAGE as the initial symptom has
also been described.
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12.  Meningeal hemangiopericytomas may resemble
meningiomas on imaging studies.
 Xray Skull
 CT Scan with/without contrast
 MRI with contrast
 MR Angiography
 DSA
 PET Scan
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13.  CT typically shows a narrow or broad-based meningeal
attachment.
 Most often the tumors appear hyperdense with focal areas of
hypodensity on unenhanced CT scans and exhibit areas of
heterogeneous enhancement with the administration of contrast
material.
 They may have features suggesting malignancy, such as
macroscopic brain invasion, or “mushrooming” inhomogeneous
contrast enhancement and irregular borders.
 Bone erosion is seen in more than 50% of hemangiopericytomas,
and hyperostosis is not a feature of this tumor.
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15.  Hemangiopericytomas are usually isointense with gray matter
and display prominent vascular flow voids onT1- andT2-
weighted MRI.
 Heterogeneous enhancement is the most common
appearance onT1-weighted gadolinium-enhanced images.
 About half the tumors have a dural tail sign.
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18.  CT and MRI characteristics that may help differentiate
hemangiopericytomas from meningiomas include:
 a narrow-based dural attachment (seen more frequently in
hemangiopericytomas)
 hyperostosis of adjacent bone (seen in meningiomas but not in
hemangiopericytomas).
 bone erosion (seen in hemangiopericytomas)
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19.  The tumors frequently exhibit characteristic arteriographic
features, including a corkscrew vascular configuration,
shunting, and a long-lasting venous stain within the tumor.
 As many as half have a significant internal carotid blood
supply and few show early venous drainage, another factor
that distinguishes them from ordinary meningiomas.
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20.  Hemangiopericytomas frequently have a dual blood supply
from the internal carotid or vertebral arteries and external
carotid arteries, but the dominant supply is from the internal
carotid rather than a primarily external source in
meningiomas.
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21.  Treatment of meningeal hemangiopericytoma requires
consideration of a multimodality approach, close follow-up, and
aggressive treatment of recurrence.
 These patients are initially seen with lesions that at first are often
mistaken for meningiomas.
 When the diagnosis of hemangiopericytoma has been made, it is
incumbent on the treating physician to recognize the malignant
character of these lesions and proceed accordingly.
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22.  The principles of surgical resection are similar to those for
meningioma. Surgery with the aim of gross total resection,
Simpson grade I, is the primary modality for treatment of
hemangiopericytoma.
 This entails resection of dura, bone, and if required, brain or
vascular structures if able to do so without producing an
unacceptable neurological deficit.
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23.  Every effort should be made to achieve complete removal at
the initial resection because surgery for recurrence is often
more difficult and is less effective.
 In large series reporting surgery for these tumors, complete
resection was possible in 50% to 77% of cases.
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25.  If complete removal is not possible, adjuvant radiation
therapy is recommended. However, adjuvant radiation does
not improve overall survival but does improve local
recurrence.
 Disease-free survival is demonstrably longer after complete
resection, and recurrence is higher after subtotal resection.
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26.  Preoperative embolization can be effective in reducing the
vascularity of these tumors.
 In cases in which hemangiopericytoma is highly suspected or
known, preoperative angiography and embolization can
reduce blood loss and facilitate tumor removal by significantly
reducing the blood supply to the lesion.
 Fountas and coauthors reported 50% lower average blood
loss with embolization.
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28.  Multiple series have described the experience of stereotactic
radiosurgery for residual or recurrent disease.
 Lunsford’s group reported a series in which stereotactic
radiosurgery provided local control of 80% of lesions.
 Chang and Sakamoto reported a good response in 75% of
patients.
 Even though all these studies had a small sample size, the
evidence clearly supports the use of stereotactic radiosurgery for
the treatment of recurrence or residual disease, and variable
numbers of these patients also received conventional
radiotherapy.
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3 Months Later

30.  The role of chemotherapy thus far has been insignificant.
 Recently, a new study looking at the O6-methylguanine-DNA
methyltransferase (MGMT) promotor status was performed
and found that 45% of primary hemangiopericytomas had a
methylated MGMT promotor.This postulates that treatment
with an alkylating agent, such as temozolomide, warrants
further investigation.
 Also, because of the high vascularity of these tumors,
investigations into antiangiogenic agents have begun.
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31.  Meningeal hemangiopericytoma has a relentless tendency to
recur, even after what is considered complete surgical resection.
 Allowing for variable definitions of “extent of resection” and
“recurrence,” median recurrence-free intervals after resection
have ranged from 40 to 78 months.
 Having many years of recurrence-free survival is not uncommon.
 After reviewing the literature, Schroder and colleagues found the
5-year recurrence rate to be about 60%.
 Guthrie and coworkers calculated 5-, 10-, and 15-year recurrence
rates of 65%, 76%, and 87%, respectively.
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32.  Meningeal hemangiopericytomas are unique in that they
frequently metastasize outside the CNS.
 The most common sites of metastasis are bone, lung, and
liver.
 Guthrie and colleagues found rates of metastasis at 5, 10, and
15 years of 13%, 33%, and 64%, respectively thus making
metastasis likely with prolonged survival.
 Intra-axial seeding of meningeal hemangiopericytomas is
extremely rare.
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34.  Guthrie and coworkers found that the median survival after
the first operation was 60 months, with actuarial 5-, 10-, and
15-year survival rates of 67%, 40%, and 23%, respectively.
 This is comparable to the cumulative survival rates of
approximately 65%, 45%, and 15%, respectively, compiled by
Schroder and colleagues from a review of 118 cases in the
literature up to 1985.
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35.  Recently, Damodaran and coauthors reported survival rates
that were slightly higher at 79%, 56%, and 44%, respectively,
with a median survival of 216 months.
 They attributed this to a higher percentage of patients
obtaining gross total resection (85% versus Guthrie’s 55%).
This again supports the notion that initial gross total resection
improves survival.
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36.  Extraneural metastasis is a devastating occurrence and
significantly shortens survival.
 In the Mayo Clinic series, 10 of 44 patients experienced
extraneural metastasis at an average time of 99 months.
 The average length of survival after diagnosis of metastasis was
24 months.
 In contrast, for 5 patients alive at 99 months in whom metastasis
did not develop, median additional survived was more than 3
times longer at 76 months.
 Melone and coauthors reported that mean survival in low-grade
(WHO II) tumors was 256 months compared with 142 months in
the high-grade (WHO III) group.
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38.  Meningeal hemangiopericytoma is an aggressive extra-axial CNS
tumor that behaves like a soft tissue sarcoma.
 It has a relentless tendency for local recurrence, and distant
metastasis remains a threat.
 The best opportunity to help the patient is at the first surgery,
where every effort should be made to achieve complete removal.
 If there is any doubt about residual tumor, surgery should be
followed by radiotherapy, radiosurgery, or both.
 Long-term observation, along with periodic chest radiographs and
work-up for bone pain and abnormal liver function test results to
rule out metastasis, is required for all patients.
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