Cerebellopontine angle metastasis of a neuroendocrine tumor mimicking vestibular schwannoma: A case report
- Department of Neurosurgery, Graduate School of Medicine, Suita, Osaka, Japan,
- Department of Gastroenterology and Hepatology, Graduate School of Medicine, Suita, Osaka, Japan,
- Department of Pathology, Osaka University, Graduate School of Medicine, Suita, Osaka, Japan.
Noriyuki Kijima, Department of Neurosurgery, Osaka University, Graduate School of Medicine, Suita, Osaka, Japan.
DOI:10.25259/SNI_117_2022Copyright: © 2022 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, transform, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Shuhei Yamada1, Noriyuki Kijima1, Manabu Kinoshita1, Shinichiro Shinzaki2, Kazuaki Sato3, Kansuke Kido3, Ryuichi Hirayama1, Naoki Kagawa1, Tetsuo Takehara2, Eiichi Morii3, Haruhiko Kishima1. Cerebellopontine angle metastasis of a neuroendocrine tumor mimicking vestibular schwannoma: A case report. 23-Jun-2022;13:264
How to cite this URL: Shuhei Yamada1, Noriyuki Kijima1, Manabu Kinoshita1, Shinichiro Shinzaki2, Kazuaki Sato3, Kansuke Kido3, Ryuichi Hirayama1, Naoki Kagawa1, Tetsuo Takehara2, Eiichi Morii3, Haruhiko Kishima1. Cerebellopontine angle metastasis of a neuroendocrine tumor mimicking vestibular schwannoma: A case report. 23-Jun-2022;13:264. Available from: https://surgicalneurologyint.com/surgicalint-articles/11671/
Background: Neuroendocrine tumors (NETs) are uncommon neoplasms arising from neuroendocrine cells and are rarely associated with intracranial metastases.
Case Description: We discuss the case of a 74-year-old woman with a right CPA tumor. She had a history of retroperitoneal NET, but was diagnosed with vestibular schwannoma due to a right-sided hearing loss and a right CPA tumor along the VII and VIII nerves. After a 3-year follow-up, she presented with repetitive vomiting, a 1-month history of gait instability, and a 3-month history of general fatigue. Brain imaging revealed tumor growth and edematous changes in the right cerebellum. She underwent retrosigmoid craniotomy and partial resection. Histopathological examination revealed metastatic NET. She underwent stereotactic radiosurgery for residual lesion and, at 11 months of follow-up, the lesion was confirmed to have shrunk on magnetic resonance imaging (MRI).
Conclusion: This is the first case to report the natural course of cerebellopontine metastasis of a NET. The differential diagnosis of CPA tumors is diverse, and, in our case, we suspected a vestibular schwannoma because of the typical symptoms and imaging features. However, the tumor grew relatively faster than expected and showed intratumoral hemorrhage during the 3-year follow-up. Therefore, in patients with a history of a NET, a careful follow-up is advisable even for lesions highly suspected to be another benign tumor on MRI. Careful follow-up imaging and appropriate treatment strategies were useful to manage the brain metastasis. Although NETs metastasizing to the CPA are extremely rare, this possibility should be considered when patients with NETs have intracranial lesions.
Keywords: Brain metastasis, Case report, Cerebellopontine angle tumor, Neuroendocrine tumor, Neuroendocrine tumors, Vestibular schwannoma
Neuroendocrine tumors (NETs) are uncommon neoplasms arising from neuroendocrine cells. The overall incidence is an estimated 1–4 patients/100,000 population/year.[
A 74-year-old woman presented to our department for the follow-up of a brain metastasis from a NET. At 65 years of age, she had abdominal pain and gross hematuria, was diagnosed with a primary retroperitoneal NET, and underwent laparotomy at another hospital. She had a left obturator lymph node metastasis at the time of diagnosis and had lung metastasis at 69 years of age. She had been administered octreotide at 70 years, carboplatin and etoposide at 72, and streptozotocin at 73, but all these drugs were discontinued due to disease progression. At 74, she was diagnosed with brain metastases and underwent tumor resection in the left parietal and right frontal lobes at another hospital.
When she presented to our department, a right CPA tumor was observed, and she had a right-sided hearing loss. Since it was located along the VII and VIII nerves and the right internal auditory canal appeared dilated on imaging, it was diagnosed as vestibular schwannoma [
Contrast-enhanced magnetic resonance imaging (CE-MRI) findings of the cerebellopontine angle lesion. (a) Images taken on the first consultation showed a suspicious lesion of about 12 mm in size, resembling a vestibular schwannoma, at the right cerebellopontine angle. (b) CE-MRI images 2 years after the first consultation (13 months before admission) showed no change in the tumor size. (c) CE-MRI images taken 7 months before admission showed an intratumoral cyst and tumor growth to 20 mm. (d) CE-MRI taken 1 month before admission showed intratumoral hemorrhage, edematous changes in the right cerebellum, and tumor growth to 27 mm.
Computed tomography (CT) scan and MRI revealed tumor growth, edematous changes in the right cerebellum, and hydrocephalus [
Imaging findings on the day of admission. Computed tomography scan (a), contrast-enhanced magnetic resonance imaging (CE-MRI) (b), and fluid-attenuated inversion recovery (c) images on the day of admission showing the tumor (arrow), hemorrhage (arrowhead), and extensive edematous changes in the right cerebellum. CE-MRI (d) showed the enlargement of lateral ventricles.
Histological findings indicating metastatic neuroendocrine tumors. Hematoxylin and eosin staining showed monotonous tumor cells with round nuclei and eosinophilic cytoplasm arranged in nested or trabecular pattern (a). Immunohistochemically, tumor cells were positive for cytokeratin (b), synaptophysin (c), and CD56 (d), although they were negative for chromogranin A (e). Ki-67 labeling index was 5.7% (f).
NETs are a rare, heterogeneous group of neoplasms arising from neuroendocrine cells.[
The differential diagnosis of CPA tumors is diverse; the most common being vestibular schwannoma (70–90%), followed by meningioma (5–15%), epidermoid cyst (6%), and lipoma (1%).[
There is no standard treatment for intracranial metastases of NETs due to their rarity. Treatments include surgery, stereotactic radiosurgery (SRS), whole-brain radiation therapy (WBRT), and systemic chemotherapy, either alone or in combination.[
Brain metastases from NETs are highly vascular and the complication rates (13% mortality and 7% morbidity) of resection are reported to be higher than those of other tumors.[
Although WBRT after resection of carcinoid brain metastases has been reported to prolong the survival time,[
The 5-year survival rate for NETs and those with distant metastases excluding the brain are reported to be 60–67%[
We encountered a case of a primary retroperitoneal NET that metastasized to the CPA, initially resembling a vestibular schwannoma on imaging. Careful follow-up imaging and appropriate treatment strategies were useful to manage the metastasis. Although NETs metastasizing to the CPA are extremely rare, this possibility should be considered when patients with NETs have intracranial lesions.
The authors certify that they have obtained all appropriate patient consent.
There are no conflicts of interest.
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