Multiple Bilobed Orbital Schwannomas: A Rare Sight

A 60-year-old lady presented with long-standing progressive, non-axial proptosis of 8-year duration associated with superior sulcus fullness, significant upper and lower eyelid retraction, and an early grade of cataract in the OD (Fig. A and B). Visual acuity had reduced to 20/100 in the OD with choroidal folds on the posterior pole on fundus examination. The other eye showed a mild grade of upper eyelid retraction with an early grade of cataract with the normal posterior segment. CT-scan of the orbit revealed 2 well-defined heterogenous ovoid lesions in the right intraconal space indenting the globe (dotted lines, Fig. C and D). The optic nerve was made out separately in few cuts. She was planned for an excision biopsy of the orbit via the superior lid crease incision. There were 2 separate lesions with an intact capsule. The lesions were removed in toto with the aid of a cryoprobe one after the other. Both the excised lesions were bilobed having different dimensions (*, Fig. E and F). Histopathology showed solid areas within the 2 well-encapsulated solid cystic lesions which were hypercellular with Antoni type A and hypocellular with Antoni type B like areas. The hypercellular areas showed spindle cells with tapering ends and elongated nuclei whereas the hypocellular areas showed numerous foamy macrophages consistent with the diagnosis of Orbital Schwannoma. The proptosis resolved with improvement in the visual acuity to 20/50 at 6 weeks.

Orbital schwannomas are known to be isolated in presentation and most commonly arise from the sensory branch of the ophthalmic division of the trigeminal nerve. Bilobed schwannomas and more so, multiple in the same orbit are a rare occurrence. To the best of our knowledge, there has been no report of multiple orbital intraconal bilobed schwannomas in literature.

FIG.: Multiple bilobed orbital schwannomas.