Vol.2, No.7, 390-394 (2013) Case Reports in Clinical Medicine
http://dx.doi.org/10.4236/crcm.2013.27104
Metaplastic meningioma with pure and extensive
cartilaginous transformation: A diagnostic dilemma *
Oumar Coulibaly1#, Justin Onen1, Amal Harmouch2, Boutarbouh Majhouba1, Adil Melhaoui1,
Y asser Arkha1, Loubna Rifi1, Said Derraz1, Sanaa Sefiani2, Abdessamad El Ouahabi1,
Abdeslam El Khamlichi1
1Department of Neurosurgery, Hôpital des Spécialités, CHU Ibn Sina, Rabat-Salé, Morocco;
#Corresponding Author:
2Department of Pathology, Hôpital des Spécialités, CHU Ibn Sina, Rabat-Salé, Morocco
Received 17 July 2013; revised 20 August 2013; accepted 5 September 2013
Copyright © 2013 Oumar Coulibaly et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Meningiomas are the most common extra-axial
central nervous system tumours and often dis-
covered in the middle to late adult life and es-
pecially in women. About 85% - 90% of men-
ingiomas are benign, 5% - 10% are intermedi-
ate-grade, and 3% - 5% are malignant. Metaplas-
tic meningioma is a rare subty pe of WHO Grade I
meningioma histologically characterized by the
presence of mesenchymal components. The pre-
sence of pure and extensive cartilaginous dif-
ferentia tion in meningio mas is extremel y rare and
remains a diagnostic dilemma. We report, per-
haps the first case of this entity in a 52-year-old
woman and discuss the pathogenesis, the im-
aging features and the h isto pathologicals data.
Keywords: Meningioma; Metaplastic Mening io ma;
Pure Cartilaginous Differentiation;
Diagnostic Dilemma
1. INTRODUCTION
Meningiomas are the most extra-axial central nervous
system tumours and often discovered in the middle to
late adult life, especially in women, and account approxi-
mately 15% - 30% of all intracranial tumors [1]. They
are classified into three groups according to the World
Health Organisation (WHO) grading system based upon
morphologic criteria with characteristic pathologic and
imaging features: benign meningiomas in 85% - 90%
(WHO Grade I), atypical meningiomas in 5% - 10%
(WHO Grade II) and malignant meningiomas in 3% - 5%
(WHO Grade III) [2]. Considering this grading, most of
symptomatic patients, in whom the diagnosis of men-
ingiomas is suggestive, undergo a surgical resection to
relieve neurological symptoms and often allow us to
guide therapeutic implications after histologic data. But
sometimes, the diagnosis remains difficult despite all
these efforts. Metaplastic meningioma is a rare subtype
of WHO Grade I meningioma histologically character-
ized by the presence of mesenchymal components, in-
cluding osseous, cartilaginous, lipomatous, myxoid or
xanthomatous and cartilaginous tissue [3]. But, the pres-
ence of pure and extensive cartilaginous differentiation in
this entity of meningiomas is very uncommon. We discuss
herein the diagnostic dilemma in this kind of meningioma.
2. CASE REPORT
A 52-year-old woman, followed for diabetes type II on
nutritional regime, had been admitted in our department
for a 10-year history of isolated headaches for which she
opted for self medication by analgesics. Due to persis-
tence of the headaches and despite analgesic therapy, she
sought medical help in our department to ascertain the
probable underlying cause. On admission, neurological
examination was strictly normal (no deficit and no pa-
pilledema on ophthalmological exam). A differed brain
CT scan was done and revealed a left parietal spontane-
ously hyperdense and heterogeneous lesion with no sig-
nificant modification following contrast injection and
suggestive of dural and bone infiltrations (Figure 1).
Cerebral MRI to refine the radiologic diagnosis comple-
mented these data. Axial, sagittal and coronal contrast
enhanced T1W MRI showed the same heterogeneous
lesion not much modified by Gadolinium injection with
probable dural and bone thickening and without brain
edema or midline shift (Figure 2). Our initial diagnosis
*Disclosure: The authors have no personal financial or institutional
interest in any of the drugs, materials, or devices described in this
article.

O. Coulibaly et al. / Case Reports in Clinical Medicine 2 (2013) 390-394 391

(a) (b) (c)
Figure 1. CT scan views showed a left parietal spontaneous hyperdense and heterogeneous lesion (a) with no significant much
modification following contrast injection (b) and suggesting of dura and bone infiltrations (c).
(a) (b) (c)
Figure 2. Axial (a), sagittal (b) and coronal (c) contrast enhanced T1W MRI showed a left parietal heterogeneous lesion not
much modified by Gadolinium injection with probable dural and bone thickening and without brain edema or parenchyma shift.
basing on the radiological appearances was parietal con-
vexity meningioma or intracranial tuberculoma. She un-
derwent a left craniotomy centred on the lesion that per-
mitted an “en bloc” resection of this tumour together
with the overlying dura (Simpson’s Grade I). Per opera-
tively, the lesion was yellowish, firm and totally hard,
with a very good plain of cleavage, and a very loose
dural attachment, leaving a cavity that was in conformity
to the shape of the lesion and measuring 4.5 cm × 2.5 cm ×
1.5 cm (Figure 3). Extemporaneous histopathological
examination was in favour of a cartilaginous tumor.
These histological data were accepted with difficulty by
our team and we recommended extensive studies in order
to properly confirm the diagnosis. Finally, the diagnosis
of metaplastic meningioma with extensive cartilaginous
transformation was made after HES staining (Figure 4).
Postoperative CT and MRI scans revealed no residual
tumour (Figure 5). She was discharged from hospital
without neurological signs 08 days after surgery and is
symptom-free 24 months following surgery.
3. DISCUSSION
Tumors derived from “meningeal cells” were described
in the older medical literature on several names, depend-
ing on their source and published as psammoma, dural
sarcoma, dural endothelioma, fibrosarcoma, angioendo-
thelioma, endotheliosis of the meninges, meningeal fi-
broblastoma, meningoblastoma, mestothelioma of the
meninges, and others [4,5]. But in 1922, Harvey Cushing
(1869-1939) had been the first to propose the term of
“meningioma” to describe these tumors and to end of to
a series of appointments without end [4]. These men-
ingiomas are the most common primary extra-axial in-
tracranial tumors and represent one-third of all such tu-
mors [6]. They exhibited a wide spectrum of microscopic
appearance and capacity for mimicking the histological
features of other neoplasms [7]. They are almost pre-
dominantly benign, slow growing lesions and constitute
15% - 30% of all intracranial tumors [8]. They occur two
or three times more commonly in women between 40
and 70 years old. Regarding their capability to express
both mesenchymal and epithelial characteristics, the
1993 WHO classification of the tumors of the meninges
recognized some histologic variants of meningiomas
from which a metaplastic meningioma was listed [9].
The current WHO histopathological classification deter-

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 
(a) (b) (c)
Figure 3. Operative view showing dimpling at the dural surface (a), parenchymal remodelling conforming to the tumour shape
(b), removed tumour specimen (c).


 
(a) (b) (c)
Figure 4. (a) HES X 100, chondroid pure tissue sheltering (surrounding) arachnoid proliferation (see arrows); (b) HES X 400,
arachnoid cells with pseudo inclusions wound in clusters; (c) HES X 100, regular and pure chondroid tissue.
 
(a) (b) (c)
Figure 5. Postoperative CT scan showing no residual tumour (a); bone-flap on bone window (b); Postoperative MRI view
showing no residual tumour (c).
mines 15 separate histopathological variants of men-
ingiomas that correspond to 3 grades of malignancy:
typical or benign meningiomas (Grade I), atypical men-
ingiomas (Grade II) or malignant meningiomas (Grades
III and IV) [10,11]. This subtype of meningiomas called
“metaplastic meningioma” and rated as WHO Grade I
meningioma, refer to a group of tumors marked his-
tologically by the presence of focal mesenchymal dif-
ferentiations or components, including osseous, cartilag-
inous, lipomatous, myxoid or xanthomatous tissue [3,11].
These morphological and histological changes in men-
ingiomas pose therapeutic challenges to pathologists,
neurosurgeons and oncologists; this is why it was useful
to have a prompt diagnosis before therapy in this group
in order to keep their aggressiveness. Becker C. et al. in
1999 describe a case of metaplastic meningioma from
which it was noted large areas of a typical meningothe-
lial meningioma with numerous cartilaginous islands and

O. Coulibaly et al. / Case Reports in Clinical Medicine 2 (2013) 390-394 393
some chondroid regions [12]. Metaplastic meningioma
with pure and extensive cartilaginous transformation is
very uncommon. In our knowledge and basing on the
literature research, any case like ours had been published
before.
The mechanism of cartilaginous transformation in
these meningiomas is still unclear and debated. However,
some hypotheses about the pathogenesis of these meta-
plasias should be discussed. Willis R.A. in 1967 [13]
argued that meningocytes are mesenchymal in origin,
multipotent mesenchymal cells have the ability to dif-
ferentiate into fibrous, mucoid, adipose, synovial, men-
ingeal, cartilaginous, osseous, hematopoietic, vascular,
or reticuloendothelial tissues and may inappropriately
respond to an unknown stimulus (precursor) to produce a
metaplastic meningioma. Awadesh, et al. in 2011 [14]
said that metaplasia is a reversible change in which one
adult cell type is replaced by another adult cell type. This
may represent an adaptive substitution of cells. This im-
plies that arachnoidal cap cells, from which meningio-
mas arise, may undergo gradual transformation into other
cell types such as fat, bone, cartilage and myxoid tissue.
But this variant differentiation has no prognostic signifi-
cance [15]. Despite all these explanations, we are not
able to confirm why these metaplastic changes occur in
some meningiomas and why not in others. Jing Xiang
Hung et al. in 2011 also said, to date it is not known how
they occur too [16]. The clinical features found in our
patient are similar to other clinical course of meningioma
in this location, but the radiological finding could not
precise the diagnosis prior the operation. This is why, the
authors thought to others differentials diagnosis before
surgery. Our patient was successfully operated with
gross total removal. These data are supported by Ulivieri
S. et al. (2008) who argued, the imaging data and a sur-
gical strategy had to be always valued and used [17].
Histologically in our case, there was essentially a pure
and regular cartilaginous tumor proliferation with very
focally small clusters of meningeal cells rounded nucleus
containing intranuclear inclusions and clear cytoplasm
scanty. Becker et al. (1999) [12] also described a typical
meningothelial meningioma from which numerous carti-
laginous islands and some chondroid regions, obviously
of intermediate (meningothelial/cartilaginous) differen-
tiation could be seen. However, Jing X. H. et al. [16]
described a case of an intracerebral metaplastic men-
ingioma with prominent ossification and extensive calci-
fication. Meningiomas with a pattern corresponding to at
least rare two histological variants (secretory and lipo-
matous components or chordoma-like and chondroma-
like structures) have been sporadically reported [18,19].
In our knowledge, our case is the unique published me-
taplastic meningioma to be a purely and extensive carti-
laginous differentiation. These extensive cartilaginous
metaplasias are very unusual but have similar prognosis
behaviour as the other subtypes in Group I. Unfortu-
nately, true that “tumors from meningeal cells” called
meningiomas now had been outlined since the sixteenth
century; but they continue to be a challenging environ-
ment in the neurosurgeon’s daily activities especially
with these constant changes and very low risk of recur-
rence or aggressive growth. Such research is still pending
to unravel this mystery.
4. CONCLUSION
Metaplastic transformation in meningiomas may fol-
low a long-standing tumour (meningioma) development,
which denotes a change from arachnoid to mesenchymal
components. How much time these metaplastic changes
take? After this transformation, it is not clearly known
the state of events that follow. As was the case with our
patient, it is possible that the lesion remained stable
thereafter. These lesions pose a diagnostic dilemma on
standard brain imaging techniques. Till presently, there is
no clear-cut therapeutic protocol, but proponents for sur-
gical strategy abound. Therefore, we do feel that future
research is required to unravel the mystery that surrounds
this particular type of metaplasia and whether it does
harbour the possibility of evolution. For the moment,
radical resection remains the rule.
5. ACKNOWLEDGEMENTS
We would like to thank Mrs. Barry Najah for her supports for this
manuscript.
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