Metaplastic meningioma with pure and extensive cartilaginous transformation: A diagnostic dilemma

doi:10.4236/crcm.2013.27104

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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: [email protected]

2Department of Pathology, Hôpital des Spécialités, CHU Ibn Sina, Rabat-Salé, Morocco

Received 17 July 2013; revised 20 August 2013; accepted 5 September 2013

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-

O. Coulibaly et al. / Case Reports in Clinical Medicine 2 (2013) 390-394

392



 

(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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