Microsurgical Resection of Hybrid Nerve Sheath Tumor Involving the Orbit and Lateral Wall of the Cavernous Sinus: 2-Dimensional Operative Video

Abstract

Surgical removal of the tumor involving both the orbital and cavernous sinus remains challenging. Hybrid nerve sheath tumors (HNSTs) are defined as benign peripheral nerve sheath tumors with combined features of more than one type of benign peripheral nerve sheath tumors, including schwannoma, neurofibroma, and perineurinoma.1 They rarely arise from the orbit.1-3 This video shows the microsurgical resection of HNST involving both the orbit and lateral wall of the cavernous sinus. A 43-yr-old woman presented with 1-yr history of a slowly growing painless mass in her left medial eyelid. Neuroimaging examinations demonstrated a multilobulated and well-demarcated mass with a heterogeneous enhancement located in the extraconal region, just above the levator muscle, and extending from the eyelid to the middle fossa through the superior orbital fissure. Based on the neuroimaging features, we diagnosed it as trigeminal schwannoma involving the orbit and lateral wall of the cavernous sinus preoperatively. We performed left frontotemporal craniotomy with superolateral orbitotomy to gain access to the tumor. The tumor was grayish yellow and relatively firm. No intact nerve fibers of the frontal and ophthalmic nerves could be identified, making the diagnosis of the tumor originating from both nerves. Finally, we completely resected the tumor, which was confirmed by postoperative magnetic resonance images. Her postoperative course was uneventful, except for transient diplopia and expected left forehead hypesthesia. The pathology returned to HNST containing schwannoma and neurofibroma with no malignancy. The patient consented to the procedure prior to the surgery. And, the patient consented to the publication of their image.

Diagnosis and Treatment of Peripheral and Cranial Nerve Tumors with Expert Recommendations: An EUropean Network for RAre CANcers (EURACAN) Initiative

“…Typically, HNST consists of a painless mass in subcutaneous tissue or dermis [ 48 ]; when large peripheral nerves or spinal nerves are involved, the tumor may be associated with pain or neurological impairment. The most common site of HNST are the fingers [ 49 ], but some rare cases arise from cranial nerves [ 50 , 51 , 52 ]. Hybrid schwannomas/perineuriomas are sporadic [ 52 ], while hybrid neurofibroma/schwannomas are strongly associated with NF1 and 2, and schwannomatosis [ 53 ].…”

“…The most common site of HNST are the fingers [ 49 ], but some rare cases arise from cranial nerves [ 50 , 51 , 52 ]. Hybrid schwannomas/perineuriomas are sporadic [ 52 ], while hybrid neurofibroma/schwannomas are strongly associated with NF1 and 2, and schwannomatosis [ 53 ]. Hybrid neurofibroma/schwannoma is the most represented morphology (71%) in schwannomatosis [ 53 , 54 ], while hybrid neurofibroma/perineurioma has been reported in association with NF1 [ 55 , 56 ].…”