Ectopic orbital meningioma: a retrospective case series

To evaluate the ophthalmic manifestations and radiographic features of ectopic orbital meningioma to improve diagnostic accuracy.

Patient data from patients admitted to our institution during a 217-month period from August 1999 to September 2017 were included. Patient ophthalmic manifestations, radiographic features (CT and MRI), diagnosis, pathology, therapeutic regimens, and prognosis were retrospectively reviewed.

Six patients with ectopic orbital meningioma were identified. The mean age at the first visit was 33.2 years (range, 7–56 years). All six patients displayed manifestations of exophthalmos, upper eyelid oedema, and motility impairment with a mean history of illness of 20.3 months (range 3–72 months). Optical lesions were located in the superonasal extraconal compartment (3/6, 50%), bitemporal extraconal compartment (1/6, 16.7%) and orbital intraconal compartment (2/6, 33%). Radiographic features were ill-defined, heterogeneous, enhancing soft tissue masses with extraocular muscular adhesion (6/6, 100%) and calcification (1/6, 16.7%), not adjacent to the optic nerve and not extending along the dura. Six cases were treated intraoperatively with complete surgical resection, indicating that all lesions were independent of the optic nerve and sphenoid ridge. The histopathologic classification was mostly of meningothelial cells (5/6, 83%). Immunohistochemistry revealed EMA and vimentin to have positive expression in all six cases, while two cases were calponin-positive and strongly expressed in the olfactory bulb. Postoperatively, lesions caused no visual impairment, and there were no cases of recurrence.

Ectopic orbital meningiomas are rare tumours that are not easily diagnosed without postoperative histopathology. This report highlights some of the distinguishing features of isolated orbital lesions, especially around the location of frontoethmoidal suture. Accompanying upper eyelid oedema and eye mobility restriction were observed to be dissimilar to other orbital tumours. In these cases, a diagnosis of ectopic orbital meningioma should be considered.