Extra-axial Desmoplastic Medulloblastoma in Adult Cerebellopontine Angle: Case Report and Noninvasive Molecular Subgrouping Utilizing Magnetic Resonance Imaging-Based Radiomics Nomogram.

Cerebellopontine angle (CPA) is an atypical site for adult medulloblastoma (MB) with only 12 cases reported in pure extra-axial location. None was predicted on preoperative imaging while the most common misdiagnosis was petrous meningioma. We add the 13th case to this list, attempting to reiterate the radiological features for preoperative prediction of this rare pathology on conventional magnetic resonance imaging (MRI). Molecular subtyping also is not yet reported for adult extra-axial CPA MB. We propose the routine use of MRI-based nomograms, in atypical CPA extra-axial masses, for noninvasive prediction of molecular subgroup, especially in resource-limited setups that lack the facility of genetic profiling.