1008 Case 2

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C A S E O F T H E M O N T H O C T O B E R 2 0 0 8 ( C A S E 2 )

A 33-YEAR-OLD CHINESE WOMANWITH A LEFT FRONTAL

TUMOR

CASE HISTORY

A 33-year-old Chinese woman presented with intermittent slurring

of speech, dysphasia together with right upper limb and facialweakness for two months with gradual worsening of the symptoms.

Physical examination found decreased pin-prick sensation over

right C6 to C8 dermatome and impaired proprioception in right

hand. CT scan with contrast showed a well-demarcated contrast-

enhancing left frontal tumor measuring 4.5 ¥ 4.2 ¥ 3 cm with

perilesional edema and slight mass effect. Cystic changes were

observed. The tumor was close to the cortical surface but not con-

nected to the meninges (figure 1). Surgical exploration found a

non-encapsulated, well-circumscribed, vascularized tumor in the

left frontal lobe. Tumor debulking under intraoperative cerebral

function monitoring was performed. Around 95% of tumor was

removed but complete excision could not be achieved due to sig-

nificant decrease in amplitude of the brain motor evoked potentials.

The patient recovered well after the operation with complete resto-

ration of the function in the precentral and postcentral gyri as well

as Broca’s area.

PATHOLOGIC FINDINGS

Multiple pieces of soft greyish fragments altogether measuring

3 ¥ 2 ¥ 2 cm in aggregate were sent for pathological examination

in fresh state. They were used in intraoperative cytologic smear,

frozen section and subsequent histology as well as ultrastructural

examination.

Intraoperative smears showed loose aggregates of polygonal and

rhabdoid cells with eccentric nuclei and abundant cytoplasm. Intra-

cytoplasmic inclusion bodies were occasionally seen. No signifi-

cant cellular atypia or necrotic material was discerned. A glial

fibrillary background was not evident. Neither psammoma bodies,

intranuclear inclusions, nor papillary structures were found.

Histologic sections showed a malignant tumor arranged in sheets

and pseudopapillary pattern (figure 2).A distinct border was appre-

ciated between the tumor and non-tumorous glial tissue. Most

of the tumor cells displayed a rhabdoid appearance with uniform,

eccentric nuclei and eosinophilic cytoplasm. Intracytoplasmic

globules were observed in places (figure 3). Some of the tumor

cells showed a primitive appearance. Perivascular pseudorosettes

as characterized by stout cytoplasmic processes radiating towards

central hyalinized blood vessel were easily found (figure 4). No

fibrillary matrix was seen in the stroma. Stromal hyalinization and

calcifications were focally present. No palisaded necrosis was seen.

Four mitotic figures were identified per 10 high power fields.

The rhabdoid tumor cells displayed a multilineage immunohis-

tochemical profile. They were focal but strongly immunoreactive

for glial marker glial fibrillary acidic protein (GFAP) (figure 5),

diffuse and strongly positive for neural marker S100-protein

(figure 6) and focal but strongly reactive for cytokeratin markersMNF116 and Cam5.2 (figure 7). In addition, diffuse and strong

membranous and cytoplasmic dot-like pattern was appreciated

with epithelial membrane antigen (EMA) (figure 8). The tumor

cells were diffusely positive for vimentin. No neuronal differentia-

tion was demonstrated with synaptophysin and neurofilament.

There was no loss of INI-1 protein (not shown). Dual-color FISH

analysis was performed on paraffin sections with a target probe

generated from BAC clone RP11-71G19 (22q11.23), which covers

the entire SMARCB1 gene (associated with rhabdoid tumors), and

the reference probe from RP11-494O16 (22q13.33). No deletion

was discerned. The proliferation index was approximately 10%.

The tumor cells were negative for HMB-45, actin and desmin.

Ultrastructural studies showed whorls of intermediate filaments

in the cytoplasm of the rhabdoid cells (figure 9). In addition,

microvillous projections were observed on the cell surface

(figure 10). An occasional intercellular junction was identified. No

cilia were seen.

Figure 1. Figure 2.

doi:10.1111/j.1750-3639.2009.00277.x

337Brain Pathology 19 (2009) 337–340

© 2009 The Authors; Journal Compilation © 2009 International Society of Neuropathology

8/7/2019 1008 Case 2


Figure 3.

Figure 4.

Correspondence

338 Brain Pathology 19 (2009) 337–340


8/7/2019 1008 Case 2


Figure 5. Figure 6.

Figure 7. Figure 8.

Figure 9. Figure 10.

Correspondence

339Brain Pathology 19 (2009) 337–340


8/7/2019 1008 Case 2


FINAL DIAGNOSIS

Astroblastoma

DISCUSSION

For a more complete discussion and differential diagnosis and

additional references please visit: http://path.upmc.edu/divisions/neuropath/bpath/cases/case173.html.

According to Bonnin and Rubinstein, astroblastomas are defined

histologically by the presence of astroblastic pseudorosettes and

prominent perivascular hyalinization (2). However, pseudorosettes

may be observed in other tumors (4). We agree that designation of

astroblastoma should be based on a constellation of clinical, radio-

logical and histological findings as illustrated in the current case.

Astroblastomas show an unusual organization of two cell types:

more primitive cells appear nesting within the cytoplasm of the

differentiated (“nurse”) cells (7). Both types of cells are nicely

illustrated in this tumor. To the best of our knowledge, this is the

second published case on astroblastoma with rhabdoid morphology

in the English literature (1).

A long differential diagnosis should be considered once rhab-

doid cells are encountered in a CNS tumor. These tumor cells are

typically observed in atypical teratoid/rhabdoid tumor (AT/RT)

which are rare in adults and show high proliferation (5). The pres-

ervation of INI1 protein expression in the current tumor speaks

strongly against the diagnosis of AT/RT. Another important differ-

ential diagnosis is ependymoma, especially the unusual type giant

cell ependymoma. However, the foot processes in the perivascular

pseudorosette of ependymoma should be long and indistinct rather

than short and broad as seen in this case. Finally, ultrastructural

ependymal differentiation as characterized by cilia, intracytoplas-

mic mircolumina and long zonular adherens are not identified in

our case. Other possible diagnoses include glioma, melanoma,

rhabdomyosarcoma and metastatic carcinoma, and meningioma.Apart from the unusual rhabdoid appearance in the tumor cells,

all the histopathological features typical for astroblastoma are

present in this case. These features include pseudopapillary

arrangement, astroblastic pseudorosettes, perivascular hyaliniza-

tion and calcifications, absence of fibrillary background and a

pushing tumor border. This diagnosis is also well supported by the

age of presentation, anatomical location and radiological features

of the tumor. Survival for patients with astroblastoma is variable

and depends of multiple factors including completeness of exci-

sion, histological grade and radiosensitivity (2, 3, 6). Astroblas-

toma appears to be radiosensitive but no definite chemotherapy is

available.

ACKNOWLEDGEMENT

We would like to thank Dr. Colin Smith, Senior Lecturer in Pathol-

ogy (Neuropathology) of University of Edinburgh for his expert

opinion in this case.

REFERENCES

1. Bannykh SI, Fan X, Black KL (2007) Malignant astroblastoma with

rhabdoid morphology. J Neurooncol 83:277–278.

2. Bonnin JM, Rubinstein LJ (1989) Astroblastomas: a pathological study

of 23 tumors, with a postoperative follow-up in 13 patients.

Neurosurgery 25:6–13.

3. Brat DJ, Hirose Y, Cohen KJ, Feuerstein BG, Burger PC (2000)

Astroblastoma: Clinicopathologic features and chromosomalabnormalities defined by Comparative Genomic Hybridization. Brain

Pathology 10:342–352.

4. Burger PC, Scheithauer BW (1994) Tumors of the central nervous

system. Atlas of tumor pathology, 3rd series, fascicle 10. Washington,

DC: Armed Forces Institute of Pathology.

5. Ho DM, Hsu CY, Wong TT, Ting LT, Chiang H (2000) Atypical

teratoid/rhabdoid tumor of the central nervous system: a comparative

study with primitive neuroectodermal tumor/medulloblastoma. Acta

Neuropathol 99:482–488.

6. Lau PP, Thomas TM, Lui PC, Khin AT (2006) “Low-grade”

astroblastoma with rapid recurrence: a case report. Pathology

38:78–80.

7. Mierau GW, Tyson RW, McGavran L, Parker NB, Partington MD

(1999) Astroblastoma: Ultrastructural observations on a case of

high-grade type. Ultrastruct Pathol 23:325–332.

Contributed by:

Yuen Shan Fan, FRCPA Philip C.W. Lui*,

FRCPA Fiona K.Y. Tam, MBBS Kwan Ngai Hung†,

FRCS(Ed) Ho Keung Ng*, FRCPath

Suet Yi Leung, FRCPath

Department of Pathology, Queen Mary Hospital,The University

of Hong Kong; * Department of Anatomical and Cellular

Pathology, Prince of Wales Hospital, The Chinese University of

Hong Kong; † Department of Neurosurgery, Queen Mary

Hospital, Hong Kong

ABSTRACT

Rhabdoid tumor cells are typically observed in atypical teratoid/

rhabdoid tumor (AT/RT) but may also be seen in meningioma,

glioma, melanoma, rhabdomyosarcoma and metastatic carcinoma.

We present an astroblastoma with unusual rhabdoid features which

is rarely described in the English literature. Apart from the rhab-

doid tumor cells, all the histopathological features typical for astro-

blastoma are present in this case. These features include pseudo-

papillary arrangement, astroblastic pseudorosettes, perivascular

hyalinization and calcifications, absence of fibrillary background

and a pushing tumor border. The tumor cells display a multilineage

immunohistochemical profile. In addition, diffuse and strong

membranous and cytoplasmic dot-like pattern is appreciated with

epithelial membrane antigen (EMA). The diagnosis of astroblas-toma is also well supported by the age of presentation, anatomical

location and radiological features of the tumor. We believe that on

top of the above-mentioned unusual tumors with rhabdoid cells,

astroblastoma should also be considered in the list of differential

diagnosis.

Correspondence

340 Brain Pathology 19 (2009) 337–340


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1008 Case 2