BACKGROUND: A hybrid nerve sheath tumor is a biphasic, benign neoplasm of peripheral nerve sheaths, consisting of combinations of neurofibroma, schwannoma, or perineurioma. These tumors were recognized only recently, in 2013
they commonly occur sporadically but rarely with syndromic associations, such as neurofibromatosis syndrome, Carney complex, and schwannomatosis. With an occurrence of 1 in every 33,000 individuals, neurofibromatosis type 2 is a rare autosomal dominant condition characterized by bilateral vestibular schwannomas. Herein we report a serendipitous occurrence of a hybrid nerve sheath tumor with neurofibromatosis type 2 syndrome, with an emphasis on its diagnostic mimics. CASE REPORT: A 35-year-old Indian male patient presented to the clinic with balance dysfunction, left-sided hearing loss, and spastic weakness in all four limbs during the past 6 months. Neurological examination revealed increased motor tone in all four limbs, bilateral 4/5 limb strength, a right grip strength of 80%, and a left grip strength of 90%. Romberg's sign, Babinski sign (extensor), and Hoffman's sign were positive. No cerebellar signs were elicited. A cranial nerve examination revealed bilateral hearing impairment, with hearing of the left being greater than that of the right. Magnetic resonance imaging revealed, an ependymoma at C1-2, a hyperintensive T2 lesion (likely a meningioma), a neurofibroma at C2, and bilateral vestibular schwannomas at the cerebellopontine angle. The patient underwent tumor excision surgery under somatosensory evoked potential/motor evoked potential monitoring. The tumor at the C2 level showed a nodular arrangement with typical schwannian nodules (SOX-10 strongly positive and epithelial membrane antigen negative)
these nodules were encased by a hypocellular neurofibroma component (CD34 CONCLUSION: Neurofibromatosis type 2 syndrome is a rare condition, associated with mutations in both alleles of the NF2 (Merlin) gene, and is associated with meningiomas and ependymomas, as seen in this patient. Its occurrence alongside a spinal hybrid nerve sheath tumor is rare and can often lead to an erroneous diagnosis of other nerve sheath tumors or, rarely, a malignant nerve sheath tumor. This case highlights this rare confluence and its mimickers.