Meningiomas are the most common extraaxial central nervous system tumours often discovered in middle to late adult life and especially in women. About 85-90% of meningiomas are benign, 5-10 % are intermediate grade, and 3-5% are malignant. Metaplastic meningioma is a rare subtype of WHO grade I meningioma histologically characterized by the presence of mesenchymal components. The presence of pure and extensive cartilaginous differentiation in meningiomas is extremely rare and remains a diagnostic dilemma. We report a case of this entity in a 52 year old woman and discuss the pathogenesis, the imaging features and the histopathological data. INTRODUCTION Meningiomas are the most common extraaxial central nervous system tumours often discovered in middle to late adult life and especially in women and account approximately for 15-30 % of all intracranial tumours (Uygur Er, Do?a Gürkanlar , Atilla Kazanci et al., 2006; Markus et al., 2006). They are usually benign in about 85-90%, atypical in 5-10 % and malignant in 3-5% with characteristic pathologic and imaging features (Black et al 2007). Most patients in whom the diagnosis is suggestive of meningiomas undergo a surgical resection to relieve neurological symptoms, and the diagnosis sometimes remains difficult despite appropriate histological studies. Metaplastic meningioma is a rare subtype of WHO grade I meningioma histologically characterized by the presence of mesenchymal components, including osseous, lipomatous, myxoid or xanthomatous and cartilaginous tissue. The presence of extensive cartilaginous differentiation in this entity of meningiomas is very uncommon. We discuss herein the diagnostic dilemma in this kind of meningioma. 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 persistence of the headaches ,despite analgesic therapy, she sought medical help in our department to ascertain the probable underlying cause. On admission, neurological examination was normal (no deficit and no papilledema on ophthalmological exam). A brain CT scan was done , which revealed a left parietal spontaneously hyperdense and heterogeneous lesion with no significant modification following contrast injection and suggestive of dural and bone infiltrations(Fig.1). Cerebral MRI to refine the radiologic diagnosis complemented 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 (Fig.2).Our initial diagnosis basing on the radiological appearances was parietal convexity meningioma or intracranial tuberculoma. She underwent a left craniotomy centred on the lesion that permitted an “en bloc” resection of this tumour together with the overlying dura (Simpson’s grade I). Intraoperatively, the lesion was yellowish, firm 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 (Fig.3). Extemporaneous histopathological examination was in favour of a cartilaginous tumour. 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 (Fig.4). Postoperative CT and MRI scans revealed no residual tumour (Fig.5). She was discharged from hospital without neurological signs 08 days after surgery and is symptom-free 12 months following surgery.
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