Medulloblastomas in cerebellopontine angle: Epidemiology, clinical manifestations, imaging features, molecular analysis and surgical outcome.

Cerebellopontine angle (CPA) medulloblastoma is rare and short of system description. We attempted to clarify its epidemiology, clinical manifestations, imaging features, pathological and molecular types, and surgical outcomes. 8 patients from 7 to 52 years old were enrolled in this retrospective study, with mean age 21.6 ± 16.4 years. The most frequent symptoms were raised intracranial pressure (100%), followed by cerebellar signs (50%), decreased hearing (50%), facial paralysis (50%), abducent paralysis (50%), and facial paresthesia (37.5%). MRI demonstrated a solid CPA lesion with heterogeneously weak or significant enhancement after gadolinium administration, accompanied with peritumoral oedema (75%), cystic change (62.5%) and dural tail sign (50%), while CT showed petrous bone and internal auditory canal intact. All cases received tumor excision, with 6 (75%) cases undergoing gross total resection, and the remaining (25%) getting partial excision. Pathological examination confirmed 5 (62.5%) classic, 2 (25%) desmoplastic, and 1 (12.5%) anaplastic. Further molecular analysis identified 5 (62.5%) WNT and 3 (37.5%) SHH. Immediately after the primary surgery, 7 (87.5%) cases gained improvement of the symptoms and signs and 1 (12.5%) kept the preoperative status stable. Follow up was available ranged from 5 to 34 months, during that period 5 cases kept symptom free and 3 cases recurred/progressed. In conclusion, CPA medulloblastoma is rare and lacking of special clinical manifestations and radiological features, and should be considered in the differential diagnosis of CPA lesions. In this series the most frequent pathological and molecular type is classic and WNT. Microsurgery excision is effective to prevent progressive decline of neurological status.