Intraosseous schwannoma in the clivus mimicking chordoma treated with endoscopic endonasal surgery: A case report

Abstract

Background: Intraosseous schwannomas are extremely rare and they have not yet been reported to occur in the clivus. We report a schwannoma in the clivus mimicking chordoma and review intraosseous schwannomas of the skull. Case Description: A 62-year-old man presented with gradually worsening hoarseness with dysphagia and atrophy of the left tongue, trapezius muscle, and sternocleidomastoid muscle. Magnetic resonance imaging showed that the tumor was mainly located in the clivus, and a computed tomography (CT) scan revealed an osteolytic lesion with expansion of the clivus and preservation of the bony cortex. Endoscopic endonasal surgery was performed to diagnose and treat symptoms. The tumor was subtotally removed without any complications. The histopathological findings revealed typical schwannoma, which showed Antoni A and Antoni B patterns positive for S100 protein. Based on the preoperative imaging, intraoperative and histopathological findings, the tumor was considered to be an intraosseous schwannoma in the clivus, and no recurrence was observed after 1 year of postoperative follow-up. Conclusion: Even though the intraosseous schwannoma in the clivus is uncommon, it should be considered as a differential diagnosis if an expansive lesion without destruction of the cortical bone is shown on CT as well as iso-hyperintensity on T2-weighted magnetic resonance imaging.

Intraosseous Schwannoma of the Frontal Bone: A Case Report and Review of the Literature

“…Intraosseous schwannoma is not a commonly considered differential diagnosis, with just two cases considering this possibility pre-operatively. 14,15 Interestingly, these cases are the most recently published, and may reflect increasing awareness of this pathology as more cases emerge. Given its extreme rarity; however, its absence from most differential diagnoses is forgivable.…”

“…2,8 Table 1 provides a summary of the limited literature on intraosseous schwannoma of the skull. Except for petrous apex lesions (in which 78% of cases presented with hearing/auditory disturbance) 7,[9][10][11][12][13][14] and one case of a clival lesion causing cranial nerve IX/X/XI disturbance, 15 symptoms appear nonspecific for lesions elsewhere with the most reported being a painless mass (55%), 3,4,[16][17][18] followed by headache (18%), 1 ocular symptoms (9%), 19 paraesthesia (9%), 1 or asymptomatic (9%). 20 Optimal treatment of intraosseous schwannoma has not been established, though surgical resection appears the mainstay of therapy, being utilised in 89% of existing cases, 1,3,4,7,[9][10][11]13,[15][16][17][18][19][20] and all cases of frontal bone lesions.…”

“…One recent paper describes an endoscopic endonasal approach to a clival schwannoma. 15 The patient in this case was asked to organise whole spine magnetic resonance imaging to assess for spinal lesions suggestive of NF2. This is an important learning point, given approximately 10% of schwannomas are associated with multisystem disorders such as neurofibromatosis, schwannomatosis, multiple meningiomas and Carney complex.…”