Intraparenchymal schwannoma of the medulla oblongata. Case report

Trigeminal Neuropathy Ascribed to a Probable Intrinsic Brainstem Schwannoma of the Pons: A Case Report

Brainstem schwannomas are very rare, only 11 cases have been reported in the literature so far. We report a small intraparenchymal brainstem schwannoma of the pons, in a 37-year-old female patient who presented with a four-day history of numbness at the mandibular division of the trigeminal nerve on the left side of her face. Trigeminal neuralgia was diagnosed, and magnetic resonance imaging (MRI) showed a small intraparenchymal lesion at the level of the nuclei of the left trigeminal nerve present at the junction between the pons and left brachium pontis. A biopsy wasn’t feasible in this small lesion. We discuss the keen radiological features that helped in the presumptive diagnosis of an intrinsic brainstem schwannoma, with both intra- and extra-axial components. Our case had the earliest presentation and the smallest probable brainstem schwannoma reported so far, as well as its unique symptomatology of trigeminal neuralgia related to both the nucleus and the nerve of the fifth cranial nerve (CN V).

Brainstem intraparenchymal schwannoma: A case report and literature review

Background:

Intracranial intraparenchymal schwannomas (IS) are rare tumors that have mainly been described in case reports. Here, we report on a case of a brainstem IS and included a comprehensive literature review.

Case Description:

A 74-year-old man presented with progressive gait disturbances. CT- and MRI-imaging revealed a contrast-enhancing mass accompanied by a cyst in the dorsolateral pons. Hemangioblastoma was suspected and surgery was advised. During surgery, gross total resection of a non-invasive tumor was performed. Postoperative recovery was uneventful. Based on histopathological examination, the intraparenchymal brainstem tumor was diagnosed as schwannoma.

Conclusion:

Our extensive review illustrates that ISs are benign tumors that most often present in relatively young patients. Malignant cases have been described but form an extremely rare entity. Preoperative diagnosis based on radiological features is difficult but should be considered when peritumoral edema, calcifications, and cysts are noted. In benign cases, gross total resection of the lesion is curative. To adequately select this treatment and adjust the surgical strategy accordingly, it is important to include IS in the preoperative differential diagnosis when the abovementioned radiological features are present.

Brainstem intraparenchymal schwannoma with genetic analysis: a case report and literature review

BACKGROUND

Schwannomas 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 PRESENTATION

A 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.

CONCLUSIONS

We suggest that brainstem schwannomas might differ from conventional schwannomas in their genetic background.

Supratentorial convexity schwannoma unrelated to cranial nerves: Case report and review of the literature

Background:

Intracranial schwannoma not related to cranial nerves is rare entity, and difficult to be diagnosed preoperatively. Here, we experienced a case of convexity schwannoma mimicking convexity meningioma, and discuss about the characteristics of such cases based on the past published reports.

Case Description:

A 48-year-old man presented with a sudden onset of seizures. Brain magnetic resonance image (MRI) revealed a small mass lesion in the peripheral aspect of the right parieto-frontal lobe. The mass was isointense on T1-weighted and hyperintense on T2-weighted MRI, with homogenous enhancement after contrast medium administration. After the feeder embolization on the previous day, removal of the tumor was performed. The tumor revealed a well-demarcated, firm, spherical tumor beyond, and beneath the dura and was relatively easy to be separated from the brain. Histologically, the tumor was observed to be in subarachnoid space extending to outer space of dura-mater, intimately attached to the pia mater. The histological diagnosis was schwannoma.

Conclusion:

In our case, MRI findings are similar to convexity meningioma; however, the pathological diagnosis was schwannoma. Cerebral convexity is an extremely rare location for schwannoma. We emphasize that schwannoma, not related to cranial nerves, may arise in the subdural convexity space.

Intracerebral schwannoma: A case report and literature review

Intracranial schwannoma accounts for between 5 and 8% of intracranial tumors, whereas intracerebral schwannoma, a rare disease, accounts for <1% of intracranial schwannomas. In addition to the present case report, a total of 84 cases reported within China and elsewhere were reviewed and summarized, and the age of the tumor onset, the site of disease, imaging results, clinical presentation, pathological classification and prognosis were analyzed. The present case report described a 12-year-old female with an intracerebral schwannoma in the brainstem, who was followed-up for 5 years using magnetic resonance imaging after a surgical resection without recurrence, and clinical symptoms were reported to have completely resolved. The incidence of intracerebral schwannoma was low among cases, and the correct diagnosis was not able to be made preoperatively, and the majority of cases were diagnosed on the basis of postoperative pathology. The majority of cases analyzed were supratentorial, occurring at an age ≤40 according to previous literature. In addition, 33% of patients presented with subtentorial schwannoma, occurring at an age >40. The prognosis was classified as good (patient can live independently) for the majority of patients if surgery was able to completely resect the lesion.

Intrinsic brainstem schwannoma - A rare clinical entity and a histological enigma

Intraparenchymal schwannomas arising in the brainstem are very rare, and only eight cases have been reported in literature till now. We report an intraparenchymal brainstem schwannoma presenting with the classical clinical presentation of an intrinsic brainstem lesion, and discuss its clinicoradiological characteristics and histological origins. We highlight the importance of an intraoperative frozen section diagnosis in such cases. Intraoperative tissue diagnosis significantly may alter the surgical strategy, which should be aimed at near total intracapsular decompression of the schwannoma.

An atypical case of intracerebral schwannoma

We report a case of intracerebral cystic schwannoma in the temporal fossa manifested as a gradually worsening headache in a 49-years-old woman. Computed Tomography (CT) and magnetic resonance imaging (MRI) showed a left temporal partly cystic, partly solid mass. The preoperative diagnosis was astrocytoma or glioblastoma multiforme (GBM), but microscopic examination of the mass showed the characteristic pattern with cellular Antony A component. Immunohistochemically, the tumor was positive for S-100 protein. These findings are consistent with a schwannoma. Intracerebral schwannomas not related to cranial nerves are rare and most reported cases involved young patients.

Intraparenchymal schwannoma involving the brainstem in a young woman

Schwannomas are tumors derived from the Schwann cells, which form the myelin sheath of the peripheral nerves. Fewer than 1% of these tumors occur within the brain parenchyma without arising from the cranial nerves. Only 55 cases have been published after the first recorded case. We report a 17-year-old girl with a 3-month history of unspecific dizziness, unsteadiness, and headache. Magnetic resonance imaging showed a heterogeneous cystic lesion involving midbrain, pons, and left cerebellar peduncle. The patient underwent a retromastoid craniotomy with complete resection of the tumor. Pathologic examination was compatible with intraparenchymal schwannoma. Since the first case of intraparenchymal schwannoma involving the brainstem was described in 1980, only seven others have been reported. Diagnosis of intraparenchymal schwannoma is almost never made preoperatively. Immunohistochemical staining is crucial in distinguishing a Schwannoma from a meningioma, glial tumor, or metastatic tumor. Pathologic findings are those typical of acoustic neurinomas. Histogenesis of intraparenchymal schwannoma remains unclear, and several theories have been proposed to explain their origin. The recognition of this curable tumor and its differentiation from brainstem glioma, which generally has a less favorable outcome, is of obvious importance.

Periventricular intraparenchymal schwannoma. Case report

A 60-year-old male presented with a rare case of periventricular schwannoma. Imaging studies revealed a partially calcified, well-enhanced tumor in the periventricular area of the left frontal horn. The preoperative diagnosis was low grade glioma, but postoperative pathological findings revealed that the tumor was schwannoma. Most intraparenchymal schwannomas are benign, so total extirpation is usually curative. However, this uncommon neoplasm is difficult to distinguish from mimics, especially low grade gliomas, with only preoperative radiological findings or intraoperative pathological findings. Based on our experience and analysis of the characteristic radiological and pathological features in previous cases, we suggest that an accurate intraoperative diagnosis is possible. The key element is the combination of correct interpretation of the intraoperative pathology analysis and careful evaluation of the preoperative radiological studies. An appropriate intraoperative judgment is important, because the treatment, including the surgical management, would be totally different for schwannoma and glioma.

Imaging and clinical features of an intra-axial brain stem schwannoma

A 68-year-old man presented with a highly symptomatic brain stem tumor originally thought to be a brain stem glioma. Intraoperative MR imaging guidance was used to resect the tumor, and real-time evoked potentials improved during surgery. Pathology findings unexpectedly indicated that the tumor was an intra-axial brain stem schwannoma, a condition reported, to our knowledge, only 6 times previously in the literature. The patient made an excellent recovery with reversal of his symptoms.

Cystic schwannoma of the falx cerebri

Intracranial parenchymal schwannomas unrelated to a major cranial nerve are uncommon and dural schwannomas are rare. We report a 23-year-old woman without neurofibromatosis admitted with a 3-month history of seizures and left hemiparesis. Radiological investigation revealed a huge cystic tumour in the right cerebral hemisphere, attached to the falx cerebri. The solid part of the tumour showed contrast enhancement. The patient underwent excision of the tumour via a right-sided parietal craniotomy. The histological diagnosis was schwannoma. Recognition of these potentially curable tumours is important and they should be excised if possible.

Aggressive Intramedullary Melanotic Schwannoma: Case Report

OBJECTIVE AND IMPORTANCE:

Intramedullary melanotic schwannomas are very rare lesions; only four cases have been reported previously. We describe a patient with an intramedullary melanotic schwannoma that had a more aggressive course than those reported in the literature, and we review the theories regarding the cause of these lesions.

CLINICAL PRESENTATION:

A 35-year-old man presented with neck stiffness and paraesthesia extending down his right arm upon neck extension. A magnetic resonance imaging scan revealed an intramedullary lesion extending from C4 to C5.

INTERVENTION:

Gross total resection of the mass was performed, and pathological characteristics were consistent with a melanotic schwannoma. Two years after resection the tumor recurred, and the patient was treated with radiation therapy. The tumor progressed 2 years after radiotherapy, and at repeat resection, multiple pigmented foci were present on the surface of the spinal cord and dura consistent with metastatic seeding.

CONCLUSION:

In a patient with intramedullary melanotic schwannoma with an unusually aggressive course, careful follow-up may be essential.