Elsevier

World Neurosurgery

Volume 100, April 2017, Pages 713.e1-713.e3
World Neurosurgery

Case Report
Radiologic Dilemma in an Extra-Axial Petroclival Lesion: Low Grade versus High Grade

https://doi.org/10.1016/j.wneu.2017.01.043Get rights and content

Background

Radiologic differentiation between a low-grade and high-grade lesion is crucial when deciding extent of resection and prognostication. Occasionally, imaging features can be confusing between the 2 lesions. We report a case that presented such a radiologic dilemma. The lesion appeared benign and extra-axial on routine magnetic resonance imaging sequences. However, subtle clinical and imaging clues pointed to a high-grade lesion.

Case Description

A 27-year-old woman presented with multiple cranial nerve palsies, gait ataxia, and features of increased intracranial pressure. Computed tomography and magnetic resonance imaging showed a petroclival extra-axial contrast-enhancing lesion with areas of chunky calcification. Although choline peak on spectroscopy raised suspicion of a high-grade lesion, the primary differential diagnosis included meningioma and schwannoma considering its characteristic imaging appearance. Postoperative histopathology showed the lesion to be giant cell glioblastoma.

Conclusions

Apart from reporting a rare variant of glioblastoma in an unusual location, this case highlights atypical imaging in a glioblastoma. Brainstem edema may be a subtle indicator of the infiltrative nature of a tumor. Magnetic resonance spectroscopy may be a useful adjunct in such circumstances.

Introduction

Reliable preoperative identification of the nature of a lesion has implications for management. It helps the surgeon in deciding on the aggressiveness of excision depending on the tumor extent and location and the patient's performance status. Occasionally, there is significant overlap between the radiologic features of low-grade and high-grade tumors. We report a case in which a petroclival lesion that was seemingly extra-axial with calcification was shown to be a rare variant of glioblastoma.

Section snippets

Case Report

Informed consent was obtained from the patient for this case report. A 27-year-old woman presented with a 4-month history of left facial paresis, numbness, and difficulty in walking. She developed headache and episodes of vomiting 3 weeks previously. Examination revealed papilledema as well as partial cranial nerve III, IV, V (motor and sensory), VII, IX, and X and bilateral cerebellar involvement. Computed tomography demonstrated a possible extra-axial lesion in the left petroclival location

Discussion

The occurrence of posterior fossa glioblastoma multiforme (GBM) in adults is unusual.1 Cerebellar GBM (1% of all GBM) and exophytic brainstem GBM have been rarely reported.1, 2 Giant cell variant arising from cerebellum is even rarer.1 The clinical presentation and radiology of GCGBM are similar to conventional GBM. The median age at diagnosis is younger than patients with conventional GBM (51 years vs. 62 years), and the median survival reported was 1 year, possibly a bit better than

Conclusions

An atypical radiologic appearance confounding a high-grade lesion needs to be borne in mind. Magnetic resonance spectroscopy and relevant additional sequences may clue to aid precise diagnosis in patients with ambiguous imaging. This case also extends the spectrum of location of GCGBM to rarer sites.

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There are more references available in the full text version of this article.

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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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