Ectopic orbital meningioma: a retrospective case series

Abstract

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

Methods: 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.

Results: 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.

Conclusions: 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.

Keywords: Ectopic orbital meningioma; Ophthalmic manifestations; Pathological diagnosis; Radiographic features.

Fig. 1

a and b MRI of case 1. a coronal T1WI showing the superonasal mass (arrow). b Axial T2WI showing an ill-defined and heterogeneous mass and adjacent medial rectus (arrow). c MRI of case 2. Axial T1 showing an ill-defined and heterogeneous superonasal mass and adjacent medial rectus (arrow). d Axial CT of case 3. A well-defined intraconal mass adjacent to the anterior optic nerve (arrow). e and f MRI of case 4. e Coronal T1 W1 showing the superonasal mass and no adjacent medial rectus (arrow). f Axial T1 W1 showing the ill-defined and heterogeneous superonasal mass (arrow). g and h: CT of case 5. g Axial CT showing a well-defined intraconal lesion with a calcified mass (arrow). h Optic nerve was compressed and dislocated but integrated into the structure (arrow)

Fig. 2

a Epithelial-type meningioma with low malignancy. Tumours indicated an infiltrative growth pattern with invasion of surrounding adipose tissue (arrow), HE× 40. b Image of psammomatous meningioma, HE× 200. c-g immunohistochemistry revealed positive staining for EMA, Ki-67, Vimentin, S-100 and calponin respectively, IHC × 200. h PBS was used to replace the primary antibody as the negative control, IHC × 200