A primary intraosseous cystic meningioma: Case report

Abstract

Introduction: This is a very rare case of intraosseous cystic meningioma. There have been no reports of similar cases in the last 30 years.

Presentation of case: A 62-year-old man, suffering from a swelling of the lateral wall of the left orbit was admitted to our hospital. MRI and CT scan showed a large intradiploic lesion involving the lateral wall of the orbit and the greater wing of the sphenoid. The lesion was cystic with a mural nodule. We operated the patient and removed completely the mural nodule and the fibrous wall of cyst. Histological examination showed that the mural nodule was a benign meningothelial meningioma.

Discussion: Primary intraosseous meningiomas represent a subtype of primary extradural meningiomas; they comprise about 2% of all meningiomas and are therefore rare entities. Cystic meningiomas are rare, their incidence compared to all other types of meningiomas is of 2-4%. The presence of a meningioma with both characteristics: cystic and intraosseous, like in our case, is an exceptional occurrence.

Conclusion: The surgical management of tumor was easy; its rarity means that the case is interesting.

Keywords: Case report; Cystic; Intradiploic; Intraosseous; Meningioma; Osteolysis.

Fig. 1

A T2-weighted axial MRI: hyperintense signal alteration over a wide area in the diploic region in front of the temporal pole in the context of which is an nodular area heterogeneously hypointense. B. In the same layer, in the diploic region there is presence of an hypointense area in FLAIR sequences. C. T1-weighted MRI axial scan after administering paramagnetic contrast e.v.: slightly non- homogenous increase of signal of the globular formation in the intradiploic area.

Fig. 2

3D CT reconstruction: osteolytic alteration of the orbital wall in the same location as the MRI showed.

Fig. 3

The arrow in the photo shows the membrane of the cyst of the meningioma after removal of a very thing bone layer.

Fig. 4

Vision from the operatory microscope of the surgical field: the horizontal arrow shows the cystic cavity, the vertical one the tumoral nodule.

Fig. 5

A Haematoxylin and Eosin stained sections of the mural nodule (A, B) show a benign meningothelial meningioma (WHO Grade I) comprising cells with oval to round nuclei and small nucleoli, arranged in syncytial and lobular patterns. There are no atypical or malignant features. An area (C) showing the interface between the tumor above and the bone matrix below with the intervening fibrous cyst wall. The tumor is attached to, but does not infiltrate the fibrous wall or the underlying bone.