Abstract
BackgroundSchwannomas are neoplasms that typically arise from the myelin sheath of peripheral nerves and rarely originate within the brain parenchyma. Some case reports present schwannomas arising from the brainstem, but regrowth of the tumor and the efficacy of postoperative irradiation have not been examined. In addition, the genetic background of schwannomas arising from the brainstem has not been investigated.Case presentationA 21-year-old male presented with diplopia, dysphagia, and left-sided hemiparesis, dysesthesia, and ataxia. Intracranial imaging showed a heterogeneous mass with a cystic lesion in the pontomedullary junction. Since the tumor caused obstructive hydrocephalus, the patient underwent subtotal tumor resection. A histopathologic evaluation aided a diagnosis of brainstem intraparenchymal schwannoma. Gradual postoperative mass regrowth was recognized. Three-dimensional conformal radiotherapy was performed on the residual mass and surgical cavity. No tumor regrowth was observed 4 years after surgery. To investigate the genetic background of the tumor, target sequences for 36 genes, including NF2, SMARCB1, and LZTR1, and microsatellite analysis for loss of 22q did not show any somatic variants or 22q loss.ConclusionsWe suggest that brainstem schwannomas might differ from conventional schwannomas in their genetic background.
Highlights
Schwannomas are neoplasms that typically arise from the myelin sheath of peripheral nerves and rarely originate within the brain parenchyma
We suggest that brainstem schwannomas might differ from conventional schwannomas in their genetic background
Immunohistochemical staining for S100 protein was diffusely and intensely positive (Fig. 3d), whereas glial fibrillary protein (GFAP) and epithelial membrane anti‐ gen (EMA) were negative in the tumor cells
Summary
Schwannomas are neoplasms that typically arise from the myelin sheath of peripheral nerves and rarely originate within the brain parenchyma. Schwannomas arise from the myelin sheath of peripheral nerves and account for 8–10% of all intracranial tumors [1]. A neurologi‐ cal examination revealed bilateral abducent palsy with partial impairment of adduction in the right eye when the patient looked to the left (one and a half syndrome), dysphagia, and left-sided hemiparesis, dysesthesia, and ataxia. His family history, including schwannomas and meningiomas, was unremarkable. The fourth ventricle partially collapsed due to the mass effect, and signs of intracranial hypertension caused by obstructive hydrocephalus gradually emerged; urgent tumor resection was planned
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