Lesions Mimicking Small Vestibular Schwannomas

Area of Science:

• Neurosurgery
• Skull Base Surgery
• Neuroradiology

Background:

• Vestibular schwannomas (VSs) are the most common tumors of the cerebellopontine angle (CPA).
• Preoperative diagnosis of CPA tumors typically relies on clinical presentation and radiological imaging.
• Histopathological examination is definitive but usually performed post-surgically.

Purpose of the Study:

• To review histopathological findings in patients surgically treated for suspected VS.
• To evaluate the accuracy of preoperative imaging in differentiating VS from other CPA lesions.
• To identify challenges in diagnosing rare CPA tumors.

Main Methods:

• Retrospective review of 207 consecutive VS surgeries via the middle cranial fossa approach (2005-2015).
• Analysis of definitive histopathology from 198 surgical specimens.
• Review of preoperative magnetic resonance imaging (MRI) and computed tomography (CT) scans.

Main Results:

• Histopathology revealed 5 non-VS tumors: 3 meningiomas and 2 lipochoristomas.
• All 5 cases presented with typical VS symptoms and were suspected as VS on preoperative MRI.
• Retrospective imaging analysis did not alter the initial VS diagnosis; increased adherence noted intraoperatively in 2 cases.

Conclusions:

• Cerebellopontine angle (CPA) lesions other than vestibular schwannomas (VSs) are infrequent but must be considered.
• Preoperative imaging can be challenging for differentiating rare CPA tumors, especially small ones.
• Diagnostic accuracy relies on a combination of clinical, radiological, and definitive histopathological evaluation.