Orbital malignant meningioma: a unique presentation of a rare entity.

An elderly female with progressive proptosis was found to have an aggressive retrobulbar solid orbital mass. The mass was distinct from the optic nerve sheath and intracranial meninges, and produced concave erosion of the sphenoid wing. Operative findings demonstrated an orbital mass adherent to the dura of the superior orbital fissure. The mass did not demonstrate meningeal violation, infiltrate the superior orbital fissure, or display intracranial spread. The dura remained intact after gross total resection. Histopathology revealed a malignant meningioma with papillary and focal rhabdoid morphology and bony invasion (WHO grade III). The patient received 2500cGy of stereotactic radiotherapy in addition to gross total resection. Postoperatively, the signs and symptoms of orbital mass effect resolved (proptosis, relative afferent papillary defect, and periorbital edema) and the vision improved. There was no orbital recurrence or intracranial extension. The follow-up time was limited to eight months secondary to the patient succumbing to metastatic lung adenocarcinoma, which was demonstrated to be a separate process from the orbital meningioma. We propose the etiology of this tumor to be most consistent with an orbital malignant primary extradural meningioma - the first case reported in the literature.