Ectopic Meningioma : Report of two cases

초록

To report rare cases of ectopic meningioma of which the incidence is about 0.8%~0.9% on the English literatures, to review the literature on the subjects, and to recommend treatment.The patient, a 73-year-old woman, presented with a 10 month history of increasing proptosis and eyelid swelling of the right eye. Neuroradiologic findings were suggestive of an epidural meningioma. . A 63-year-old man, who had past history of head trauma and skull fracture 20 years ago, presented with a 7 years history of a subcutaneous lesion overlying the mid-frontal region of the scalp, which was 6 x 7cm non-tender, fixed, bony hard mass adherent to the pericranium. A CT scan of the head demonstrated the subcutaneous lesion with hyperostosis of the skull and there was no intra-cranial connection. Both patients underwent total excision of the mass, subsequently examined by histopathology.Tumor excision was performed via frontal bone craniotomy and superior orbitotomy. The mass was seemed to be originated from the orbital roof, extended to orbital space and invaded to the dura mater. Also, the mass made the erosion of the frontal bone with hyperostosis. Histopathologic examination of the tumor was consistent with atypical meningioma Conclusion. Ectopic meningiomas are rare tumors that develop from ectopic arachnoid tissue. The ectopic meningioma in Case 1 was suggested that it developed from an occasional arachnoid rest in supra-orbital wall (orbital roof). In Case 2, we suggest that this ectopic meningiomas origingated from meningeal tissue that had been trapped outside the central nervous system after the skull fracture 20 years ago. It was thought to be type 2 cutaneous meningioma of the classification by Lopez DA in 1974.