CASE REPORTS

AN ASTROBLASTOMA MIMICKING A CAVERNOUS
MALFORMATION: CASE REPORT
Luis M. Tumialán, M.D.
Department of Neurosurgery,
Emory University
School of Medicine,
Atlanta, Georgia

Daniel J. Brat, M.D., Ph.D.
Department of Pathology and
Laboratory Medicine,
Emory University
School of Medicine,
Atlanta, Georgia

Arthur J. Fountain, M.D.
Department of Radiology,
Section of Neuroradiology,
Emory University
School of Medicine,
Atlanta, Georgia

Daniel L. Barrow, M.D.
Department of Neurosurgery,
Emory University
School of Medicine,
Atlanta, Georgia
Reprint requests:
Daniel L. Barrow, M.D.,
Department of Neurosurgery,
The Emory Clinic,
1365-B Clifton Road, N.E.,
Suite 6400,
Atlanta, GA 30322.
Email: daniel_barrow@emory
healthcare.org
Received, July 5, 2005.
Accepted, November 7, 2006.

NEUROSURGERY

OBJECTIVE: Astroblastomas are rare glial neoplasms that usually occur in young adults
and have a predilection for the cerebral hemispheres. Patients typically present with
signs of increased intracranial pressure and seizures. Imaging studies reveal circumscribed, contrast-enhancing tumors that contain both cystic and solid components with
variable peritumoral edema. Hemorrhage, which suggested the presence of a vascular
lesion in this patient, has not been previously described as a feature of this neoplasm.
CLINICAL PRESENTATION: The authors report the case of a 33-year-old woman who
presented with spontaneous intraparenchymal hemorrhage. The collective radiographic
data suggested the presence of a cavernous malformation.
INTERVENTION: A right frontotemporal craniotomy was performed under frameless
stereotactic image guidance. An astroblastoma was diagnosed after resection and neuropathological examination.
CONCLUSION: A rare radiological to pathological correlation of astroblastoma is presented in which the evolving hematoma, as observed on magnetic resonance imaging
scans, complicated the radiographic diagnosis of this lesion. The clinical, radiographic,
and pathological features of astroblastomas, as well as the natural history of these rare
glial neoplasms, are reviewed. This case illustrates the capacity of astroblastomas to
hemorrhage, disguising the classic radiographic findings typical of this glial neoplasm.
KEY WORDS: Astroblastoma, Cavernous malformation, Intraparenchymal hemorrhage
Neurosurgery 60:E569–E270, 2007

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DOI: 10.1227/01.NEU.0000255336.80285.70

ailey and Cushing first described astroblastomas in their 1924 classification of
central nervous system neoplasms (17).
Although neither “astrocytic” nor “blastic,”
astroblastomas are typically solid and well circumscribed, with the characteristic histological
features of astroblastic pseudorosettes and
perivascular hyalinization (3). There has been
much controversy regarding the question of
whether astroblastomas are a subtype of
ependymomas or astrocytomas. Although
astroblastomas demonstrate many clinical and
histopathological features of ependymomas and
astrocytomas, the two have been clearly differentiated with immunohistochemical, ultrastructural, and chromosomal studies (3, 18). The
most recent World Health Organization classification of central nervous system tumors recognizes astroblastomas as a distinct entity (2).
Astroblastomas typically present in older
children or young adults and have a predilection for the cerebral hemispheres (2, 24).

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Patients present with nonspecific symptoms
such as seizures, headaches, and signs of
increased intracranial pressure (20). Radiographically, astroblastomas are large, lobulated,
and supratentorial, with both cystic and solid
components (1, 3, 19). The current body of literature indicates that prognosis is best predicted
by histology (2, 22). Well-differentiated astroblastomas may be successfully treated with gross
total resection without the need for adjuvant
therapy. Treatment for anaplastic astroblastomas, which requires surgery, remains controversial, and the roles of adjuvant chemotherapy and radiation are ill defined (2).
The authors present a patient with an acute
intraparenchymal hemorrhage who was initially thought to have a cavernous malformation based on computed tomographic (CT)
scans, magnetic resonance imaging (MRI)
scans, and conventional and CT angiography.
After craniotomy and resection of the lesion,
neuropathological examination established the

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TUMIALÁN ET AL.

diagnosis of astroblastoma. To our knowledge, this case represents the first example of an astroblastoma presenting as an intracranial hemorrhage and mimicking a vascular malformation.

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CASE REPORT
A 33-year-old woman with a medical history significant for
mitral valve prolapse experienced the sudden onset of
headache, nausea, and imbalance. She presented to an outside
institution, where she was noted to have left-sided facial weakness. A noncontrast CT scan of the head demonstrated a large
right frontal intracranial hemorrhage (Fig. 1). The patient was
managed with phenytoin and intravenous steroids.
Conventional four-vessel cerebral angiography did not reveal
the source of the hemorrhage (Fig. 2) and MRI scans with and
without gadolinium demonstrated only a partially resolving
hematoma (Fig. 3). During her hospitalization, she did not
exhibit any seizure activity or altered level of consciousness.
After an uncomplicated hospital stay with complete resolution
of her neurological symptoms, the patient was discharged.
Two months after her initial hemorrhage, the patient presented electively to our institution for further recommendations. At the time of her evaluation, the patient remained neurologically intact. Because the results of her studies suggested
the possibility of a cavernous malformation, a craniotomy for
exploration of the hematoma cavity was planned.
A right frontotemporal craniotomy was performed under
frameless stereotactic image guidance (Fig. 4). After the dura was
opened, an abnormal area on the surface of the brain became
obvious. Stereotactic guidance was used to confirm that this area
corresponded with the site at which the hematoma came closest
to the brain’s surface. A cortical
incision was made and the
hematoma cavity was entered.
After elements of an organizing
hematoma were evacuated, abnormal appearing diaphanous
vessels were identified entering
the hematoma cavity and leading to a small, tan-red nodular
mass. Using microsurgical techniques, the presumed malformation, which measured approximately 1.5 cm in diameter,
was circumferentially excised
and sent to pathology. All
remaining abnormal vessels
entering the lesion were coagulated and divided. After the FIGURE 1. Noncontrast head CT
hematoma cavity was explored scan at the time of the initial hemorunder high magnification with- rhage demonstrating heterogeneous
signal intensity within the hemaout evidence of additional
toma, which is indicative of acute
abnormal vessels, the walls of hemorrhage. The lateral component
the cavity were lined with of hematoma with a hyperattenuated
Surgicel (Ethicon, Inc., Somer- signal is suggestive of either subaville, NJ) and the wound was cute hemorrhage or the solid compoclosed.
nent of a neoplasm.

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FIGURE 2. Anteroposterior (A) and lateral (B) projections of the right internal carotid artery on conventional angiography without evidence of a vascular lesion or blush that would suggest a neoplastic lesion.

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FIGURE 3. MRI scans of the brain C
performed 24 hours after the initial
hemorrhage demonstrating an intraparenchymal hematoma. A, T2weighted image demonstrating a
large, well-circumscribed peripheral
mass with heterogeneous hyperintense signal. There is very little evidence of vasogenic edema. Astroblastomas are typically isointense on
T2-weighted images. B, T1-weighted
image without contrast revealing heterogeneous signal intensity hypointense with respect to gray matter.
C, T1-weighted image with gadolinium demonstrating homogeneous
enhancement of the rim portion with
heterogeneous enhancement of the solid portion, and the previously reported
“bubbly appearance” at the center.

Histological sections revealed a well-differentiated astroblastoma and adjacent brain tissue with evidence of recent and
remote hemorrhage and reactive gliosis. The astroblastoma
showed classic features, including numerous astroblastic
rosettes formed by elongated tumor cells containing abundant
eosinophilic cytoplasm extending a single prominent process to
a central blood vessel (Fig. 5). In contrast to ependymoma,
these rosettes are not fibrillar but rather are formed by colum-

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ASTROBLASTOMA MIMICKING A CAVERNOUS MALFORMATION

nar or cuboidal cells. Typical
of astroblastomas, perivascular hyalinization was also
prominent and, in some
regions, the hyalinization coalesced to occupy large zones
of the tumor (3, 12). The tumor
was graded as a well-differentiated astroblastoma because the mitotic rate was low
(0–1 in 10 high-power fields
and there was no evidence of
v a s c u l a r p ro l i f e r a t i o n o r
tumor necrosis. The MIB-1
FIGURE 4. Axial T1-weighted MRI index was slightly elevated
scan of the brain with gadolinium (6–8%) compared with most
performed 3 months after the initial well-differentiated astroblashemorrhage for frameless stereotactic tomas. A well-defined border
guidance on the day of surgery showwas noted at the interface of
ing a completely evolved hematoma
the tumor with adjacent brain
with little enhancement of the rim
compared with previous studies. tissue. No diffuse infiltration
Heterogeneous enhancement is lim- of the surrounding parenchyma by tumor cells was
ited to the mural nodule.
identified. The tumor was
strongly immunoreactive for glial fibrillary acidic protein, S-100
protein, vimentin, and epithelial membrane antigen (Fig. 5).
The patient awoke from anesthesia with no neurological
deficits. Postoperatively, the patient had a focal motor seizure.
After her antiepileptic medication was adequately dosed, she
had no further seizure activity and was discharged on the
third postoperative day. The patient was initially thought to
have a gross total resection, but surveillance imaging suggested the presence of persistent tumor. The patient underwent another craniotomy at an outside facility 3 months after
her initial surgery and a well-differentiated astroblastoma was
confirmed. Gross total resection was not achieved and the
patient underwent partial brain radiation (daily dose, 180
cGy; total dose, 3600 cGy) followed by three-dimensional
intensity modulated radiation therapy (daily dose, 180 cGy;
total dose, 1980 cGy). Two years after her initial surgery, the
patient has no evidence of residual or recurrent disease on
surveillance imaging.

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DISCUSSION
Astroblastomas are rare primary central nervous system
tumors with a reported incidence of 0.45 to 2.8% of primary
brain gliomas (9). Since Bailey and Cushing introduced the
term astroblastoma in 1924, there has been much confusion
regarding their natural history, diagnostic criteria, and cell of
origin (3, 5, 7, 18). In fact, astroblastomas are not accepted by all
neuropathologists as a unified clinicopathological entity
because of the inability to fully distinguish this glial neoplasm
from ependymal or astrocytic neoplasms (2). During the past
several years, a body of literature has arisen that defines astro-

NEUROSURGERY

FIGURE 5. Histopathology of a well-differentiated astroblastoma. The histological hallmark of astroblastomas is the astroblastic pseudorosette, composed
of elongated tumor cells with columnar or tapering processes oriented to a central vessel (A and B, arrows). Low magnification demonstrates a welldifferentiated, noninfiltrative tumor containing repeating units of astroblastic
rosettes (A, original magnification, ⫻200). Higher magnification demonstrates the wide, columnar structure of individual cell processes that extend to
central blood vessels in astroblastic pseudorosettes (B, original magnification,
⫻600). Immunostaining for glial fibrillary acidic protein is positive in tumor
cells of astroblastic rosettes and highlights the perivascular orientation (C,
arrow; original magnification, ⫻400).

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TUMIALÁN ET AL.

blastomas in the context of their natural history, radiographic
features, and histopathological findings (7, 13). Although astrocytomas and ependymomas may share many of these features,
recent immunohistochemical, ultrastructural, and chromosomal studies further establish astroblastomas as distinct from
these neoplasms (3, 5, 8–10, 20). However, there are no pathognomonic genetic alterations for astroblastomas, and previous
studies have only described genetic alterations as a means for
distinguishing astroblastomas from ependymomas as a pathological entity. These alterations seem to have no positive predictive value for diagnosis.
Although astroblastomas may occur in patients of any age,
older children and young adults are more commonly affected;
there is also a slight female predominance (2, 5, 9, 16).
Astroblastomas tend to occur in the supratentorial brain as
well circumscribed tumors, but have also been described in the
cerebellum, brainstem, and cauda equina (11).
Radiographic imaging demonstrates many classic features
of this tumor, which may aid the pathologist in making the
diagnosis once a histological sample has been obtained. CT
scanning depicts a large cystic lesion with occasional calcifications in the cerebral hemispheres, as well as associated mass
effect. The solid component may demonstrate a slightly
increased attenuation. MRI scanning typically reveals a spherical mass with both cystic and solid components (1). The solid
components of the mass are hypointense with respect to gray
matter on T1-weighted images and isointense on T2-weighted
images (17, 19). Despite the potential large size of astroblastomas, there is relatively little vasogenic edema observed on
T2-weighted images. The cyst walls, along with the solid component of the tumor, exhibit heterogenous enhancement with
gadolinium (Fig. 4) (1, 25).
In the setting of acute hemorrhage, as observed in the
patient presented in this report, these characteristic neuroimaging findings of astroblastoma become obfuscated and
a vascular lesion seems more likely on the basis of the initial
imaging. In a 33-year-old woman, the presence of acute hemorrhage on CT scans (Fig. 1) and a resolving hematoma with
elements of enhancement on MRI scans (Fig. 2) are suggestive
of a cavernous or arteriovenous vascular malformation or a
neoplastic process. The propensity of intracranial metastatic
lesions to bleed initially placed a metastatic process in the
differential. However, with negative routine breast examinations, a negative family history of breast, lung, and colon
cancer, no history of bloody stools, no history of weight loss,
no history of smoking, and a negative chest x-ray, a metastatic evaluation was thought to be of lower yield than a surgical procedure.
The initial unenhanced CT scan (Fig. 1) shows a heterogeneous signal within the hematoma cavity, which may be
observed in cavernous malformations or neoplastic lesions.
Even in retrospect, when compared with the location of the
nodular component of the preoperative MRI scan (Fig. 4), the
isodense-to-moderately hyperintense signal in this study is
consistent with a cavernous malformation. The MRI scans
revealed a well-delineated complex reticulated core of varying

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signal intensities, indicating hemorrhage at different stages of
evolution, which, in the context of an angiographically silent
lesion, would suggest a cavernous malformation. Further studies demonstrated this lesion to be angiographically occult on
conventional angiography, reinforcing the presumptive diagnosis of cavernous malformation. Retrospective review of the preoperative MRI scan (Fig. 4) performed for image guidance 2
months after her initial hemorrhage, however, seemed more
suggestive of a neoplasm. Intraoperative findings did not
reveal the discrete multilobulated berry-like lesion expected
with a cavernous malformation but, rather, a well-defined tan
nodule within the hematoma cavity. Previous authors have
reported similar macroscopic findings of astroblastomas in the
absence of hemorrhage (5, 21, 25).
The finding of a glial neoplasm at surgery prompted further
retrospective review of the findings of the preoperative imaging. When a cavernous malformation is in the differential diagnosis, an MRI scan sequence sensitive to dephasing should be
used to look for other areas of focal signal loss in the brain.
These signal losses represent hemosiderin deposits from previous bleeds at other sites; 25 to 50% of cavernous malformation
cases have multiple sites, as do 75% of hereditary lesions (14).
In addition, the MRI scan spin echo sequences that are most
sensitive involve a long echo time, as in a T2-weighted image
with a prolonged echo time. The signal loss is more apparent at
high field strengths than at low field strengths. More sensitive
yet are gradient echo sequences in which the T2-weighted signal loss is more profound because of the less-efficient signal
refocusing. Thus, gradient echo sequences are capable of demonstrating even minute traces of blood, such as those found in cavernous malformations (4, 14, 23).
The rarity of this tumor has prevented the generation of large
trials to develop conclusive treatment protocols (2, 6, 8). Thus,
the treatment of astroblastomas remains controversial and is
based primarily on several small case series in the literature (2,
6). Several investigators have found that prognosis seems to be
predicted by histology (10, 15, 21, 22). Bonnin and Rubinstein
(2) identified anaplastic features that were distinct from a more
differentiated growth pattern in their series of 23 patients with
astroblastomas. These authors reported a worse prognosis in
patients with anaplastic lesions, despite adjuvant therapy.
Thiessen et al. (22) corroborate this conclusion in their series of
seven patients, in which they observed that recurrences were
common in the patients with anaplastic features, despite gross
total resection, radiotherapy, and chemotherapy. Conversely,
the patients with well-differentiated features remained disease
free after gross total resection alone (22).
The current literature indicates that gross total resection has
the greatest impact on the survival of patients with welldifferentiated astroblastomas (2, 6). There is little evidence to
suggest that adjuvant chemotherapy or radiation improves survival in these patients (22). Although aggressive therapy is indicated in anaplastic astrocytomas in the form of surgery, radiation, and chemotherapy, it has been difficult to assess how each
of these modalities has altered survival (22). Nevertheless, the
radiosensitivity and chemosensitivity of astroblastomas have

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ASTROBLASTOMA MIMICKING A CAVERNOUS MALFORMATION

been established by previous cases in the literature (6). With
regard to the patient in this report, the inability to achieve gross
total resection with the second craniotomy prompted the
options of another craniotomy, continued surveillance, radiation, and chemotherapy. The patient elected to undergo radiation therapy after her second craniotomy. Two years after her
initial surgery, the patient remains disease free.

CONCLUSION
Astroblastomas are rare glial tumors that are generally noninfiltrative and well circumscribed in relation to the surrounding brain tissue. This case illustrates the capacity of astroblastomas to hemorrhage, disguising the classic radiographic
findings typical of this glial neoplasm.

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Acknowledgments
No financial support or grant assistance was received for the generation of this
study. We have no financial interest in the materials mentioned in this article.
The authors are grateful for the editorial assistance rendered by Andrea J. Porter,
M.S., and Rhonda Everett, M.P.H.

COMMENTS

T

he authors present a case report describing a patient who appeared
to have a frontal cavernous malformation that was ultimately
revealed to be an astroblastoma. It is likely that the presence of a
hematoma in the tumor made the lesion appear to resemble a cavernous malformation. In either case, the large size of the lesion and its
superficial location justified surgical intervention. This report reminds
us that certain hemorrhagic tumors can mimic vascular malformations
and should be kept in the differential diagnosis.
Steven D. Chang
Stanford, California

T

his report presents a unique occurrence of hemorrhage associated
with an astroblastoma, which has not been previously reported.
Several features of this case make it instructive. For instance, the
authors note that a T2-weighted gradient echo sequence in suspected,
but uncertain, cases of cavernoma can be helpful because of the high
multiplicity incidence of cavernomas. Because the lesion itself is rare,
the occurrence of hemorrhage further compounded preoperative diagnosis. This case is somewhat difficult from the perspective of preoperative imaging because a routine consideration of diagnostic possibilities
would not likely include astroblastomas; however, the possibility of
underlying neoplasm, whether primary or metastatic, should not be
overlooked. There is some tendency for hematomas derived from neoplasms to demonstrate more heterogeneity than hemorrhages associated with vascular malformations. Therefore, whereas vascular malformation remains one of the primary diagnostic considerations, the
somewhat heterogeneous appearance of the hematoma on both computed tomographic and magnetic resonance imaging scans in this case
brings the possibility of an underlying neoplasm into greater consideration. In summary, this is a good discussion of classic features and a
newly recognized atypical feature of astroblastomas.
Paul E. Kim
Los Angeles, California

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