Utility of Microhemorrhage as a Diagnostic Tool in Distinguishing Vestibular Schwannomas from other Cerebellopontine Angle (CPA) Tumors.

Although a majority of tumors in the Cerebellopontine Angle (CPA) are vestibular schwannomas (VS), other masses can also be seen in the region and differentiation of various CPA tumors, particularly meningiomas can be difficult on imaging alone. Treatment options may vary based on specific pathology of the CPA tumor. In this study, the presence of microhemorrhage (MH) and other imaging features such as size of lesion, cystic features and pattern of IAC extension, were evaluated as a tool in distinguishing VS from other CPA masses. A review of CPA masses in the last 11 years at our institution was performed. All the pathology proven tumors with at least 1 pre-operative MRI were considered for analysis. A T2* GRE or SWI sequence was used to assess presence of MH within the lesion. Pattern of IAC extension ('centric' versus 'eccentric') of tumor was also evaluated. A total of 147 patients were reviewed out of which 102 patients (with T2* GRE or SWI) were included for analysis of MH. 57 patients (56%) had VS as the final histopathological diagnosis and 45 patients (44%) had other types of tumor. A sensitivity of 82% and a specificity of 98% was noted for the presence of MH favoring the diagnosis of VS from other tumors (p < 0.001). All meningiomas with IAC extension (25/31) showed an 'eccentric' pattern of extension into the canal. Visualization of MH and pattern of IAC extension is useful in the differentiation of schwannomas from other CPA masses, particularly meningiomas. © Association of Otolaryngologists of India 2021.