54-year-old female with no significant past medical or ocular history presents with a nine month history of painless, worsening “foggy cloud” OS. Patient denied any history of trauma.
Exam Findings
Ocular Vitals
VA 20/20 OD, 20/80 PH 20/50 OS
IOP 14 OD, 13 OS
Pupils: 3→2mm OD, 8mm and nonreactive OS. 2+ rAPD OS
Slit lamp exam OU
Notable for relative proptosis and resistance to retropulsion OS
Hertel 13mm OD, 17mm OS
Dilated Fundus Exam OU
Optic nerve with mild temporal pallor OS, otherwise unremarkable
CT Scan
Figure 1: Axial CT remarkable for a large, well defined, ovoid space occupying mass in the left retrobulbar area, extending anteriorly towards the globe and posteriorly towards the apex. Lesion is homogeneous in composition and isodense to adjacent muscle bellies.Figure 2: Coronal CT illustrating the marked compressive effect on surrounding orbital structures.
Differential Diagnosis of Acquired Unilateral Orbital Mass
Vascular
Cavernous hemangioma (most common benign orbital neoplasm)/li>
Lymphoma, Invasive sinus (SCC, AdenoCa) or intracranial process, other metastatic disease (most commonly breast and lung)
Additional Investigations
Patient underwent lateral orbitotomy with bone flap and excision of lesion
Figure 3: H&E tissue stain remarkable for dense cellular areas with compact spindle cells and palisading nuclei surrounding acellular pink areas. Pattern consistent with verocay bodies in an Antoni A pattern.Figure 4: Antoni A and Antoni B patterns with markedly positive S100 staining.
Diagnosis
Orbital Schwannoma
Pathophysiology
Rare, slow growing, encapsulated (by perineurium) tumor arising from the nerve sheath fascicle of either motor or sensory nerves
Very rare, accounting for 1% of all tumors in the orbit
Arises from hyperplasia of myelin producing schwann cellst
Occurs in isolation, or as part of syndromes such as NF-2, Schwannomatosis, and less commonly NF-1
Most originate from branches of CN 3,4,5,6, parasympathetics, or sympathetics
Theoretically cannot occur in CN 1 or 2 because these lack sheaths composed of schwann cells
Treatment
Surgical excision
Prevent compression of optic nerve and surrounding or involved cranial nerves
Incomplete removal can lead to recurrence or intracranial extension
Decompression
If resection not possible (i.e. apical tumors)
Radiation Therapy
Risk of optic neuropathy, secondary malignancy
Prognosis
Typically good prognosis with improved VA
Must monitor for recurrence, malignant transformation
Recurrence has been noted from days to many years after excision
Residual or de novo
Deep orbitotomy: Surgical incisions
Hidden approaches
Upper lid crease incision
Caruncular approach
Conjunctival fornix approach
Conjunctival peritomy approach
Lateral canthotomy
Others:
Upper lid split
Lynch incision
Brow incision
Kronlein incision
Deep orbitotomy: preferred techniques
Subperiosteal approach*
Periosteal release at the lateral canthus
Bone contouring at the orbital rim (near lacrimal fossa)
Bone flaps
Bone flap + bone contouring*
Retractors (e.g lonestar)*
Neurosurgical cottonoids*
Finger palpation*
Suture traction on orbital mases*
Cryotherapy probe*
Medial/lateral combined approach
Combined neurosurgical approach
Navigation systems
Deep orbitotomy tips:
Prepare for the worst: obtain as wide an approach as possible
Study the anatomy then visualize the relationships
No cautery in the deep orbit
Keep fat out of your field as long as possible (subperiosteal approach)
Have an experienced assistant
Visualization requires patience
References
Daras M, Koppel BS, Heise CW, Mazzeo MJ, Poon TP, Duffy KR. Multiple spinal intradural schwannomas in the absence of von Recklinghausen’s disease. Spine (Phila Pa 1976)
Koktekir BE, Kim HJ, Geske M, Bloomer M, Vagefi R, Kersten RC. Orbital schwannomatosis in the absence of neurofibromatosis. J Craniofac Surg. 2014;25(6):2109-11.
Nagashima H, Yamamoto K, Kawamura A, Nagashima T, Nomura K, Yoshida M. Pediatric orbital schwannoma originating from the oculomotor nerve. J Neurosurg Pediatr. 2012;9(2):165-8.
Kim MS, Park K, Kim JH, Kim YD, Lee JI. Gamma knife radiosurgery for orbital tumors. Clin Neurol Neurosurg. 2008;110(10):1003-7
Delfini R, Missori P, Tarantino R, Ciapetta P, Cantore G. Primary benign tumors of the orbital cavity: comparative data in a series of patients with optic nerve glioma, sheath meningioma, or neurinoma. Surg Neurol. 1996;45(2):147-53.
Brucoli M, Giarda M, Arcuri F, Benech A. A benign isolated schwannoma of the orbit. J Craniofac Surg. 2011;22(6):2372-4.
Konrad EA, Thiel HJ. Schwannoma of the Orbit. Ophthalmolgica, Basel; 1988. p. 118-27
Goh AS, Kim YD, Woo KI, Lee JI. Benign orbital apex tumors treated with multisession gamma knife radiosurgery. Ophthalmology. 2013;120(3):635-41.
Kron M, Bohnsack BL, Archer SM, Mchugh JB, Kahana A. Recurrent orbital schwannomas: clinical course and histopathologic correlation. BMC Ophthalmol. 2012;12:44.
Khan SN, Sepahdari AR. Orbital masses: CT and MRI of common vascular lesions, benign tumors, and malignancies. Saudi J Ophthalmol. 2012;26(4):373-83.
Shields JA, Bakewell B, Augsburger JJ, Flanagan JC. Classification and incidence of space-occupying lesions of the orbit. A survey of 645 biopsies. Arch Ophthalmol. 1984;102(11):1606-11.
Kauser H, Rashid O, Anwar W, Khan S. Orbital oculomotor nerve schwannoma extending to the cavernous sinus: a rare cause of proptosis. J Ophthalmic Vis Res. 2014;9(4):514-6.
Kim KS, Jung JW, Yoon KC, Kwon YJ, Hwang JH, Lee SY. Schwannoma of the Orbit. Arch Craniofac Surg. 2015;16(2):67-72.
Yulek F, Demer JL. Isolated schwannoma involving extraocular muscles. J AAPOS. 2016;20(4):343-7.Tezer MS, Ozcan M, Han O, Unal A, Ozlugedik S. Schwannoma originating from the infraorbital nerve: a case report. Auris Nasus Larynx. 2006;33:343–345.
Konrad EA, Thiel HJ. Schwannoma of the orbit. Ophthalmologica. 1984;188:118–127
Ribeiro SFT, Queirós T, Amorim JM, Ferreira AM, Sales-sanz M. An Unusual Differential Diagnosis of Orbital Cavernous Hemangioma: Ancient Schwannoma. Case Rep Ophthalmol. 2017;8(2):294-300.
Contact
Jonathan Kim, MD, Associate Professor of Clinical Ophthalmology, A. Linn Murphree Professor and Director of the Ocular Oncology Service, jonathan.kim@med.usc.edu
Due to ongoing developments with COVID-19, we are only able to see patients with urgent eye problems at this time. If you have any questions or concerns, please call us at 323-442-6335.