Abstract
Medulloblastoma (MB) is the most common malignant pediatric brain tumor arising in the cerebellum or the 4th ventricle. Cerebellopontine angle (CPA) MBs are extremely rare tumors, with few cases previously described. In this study, we sought to describe the clinical characteristics, molecular features and outcomes of CPA MB. We retrospectively reviewed a total of 968 patients who had a histopathological diagnosis of MB at the Beijing Neurosurgical Institute between 2002 and 2016. The demographic characteristics, clinical manifestations and radiological features were retrospectively analyzed. Molecular subgroup was evaluated by the expression profiling array or immunohistochemistry. Overall survival (OS) and progression-free survival (PFS) were calculated using Kaplan-Meier analysis. In this study, 15 patients (12 adults and 3 children) with a mean age at diagnosis of 25.1 years (range 4–45 years) were included. CPA MBs represented 1.5% of the total cases of MB (15/968). Two molecular subgroups were identified in CPA MBs: 5 WNT-MBs (33%) and 10 SHH-MBs (67%). CPA WNT-MBs had the extracerebellar growth with the involvement of brainstem (P = 0.002), whereas CPA SHH-MBs predominantly located within the cerebellar hemispheres (P = 0.004). The 5-year OS and PFS rates for CPA MB were 80.0% ± 10.3% and 66.7% ± 12.2%, respectively. Pediatric patients with CPA MBs had worse outcomes than adult patients (OS: P = 0.019, PFS: P = 0.078). In conclusion, CPA MB is extremely rare and consists of two subgroups. Adult patients with CPA MB had a good prognosis. Maximum safe surgical resection combined with adjuvant radiotherapy and chemotherapy can be an effective treatment strategy for this rare tumor.
Highlights
Medulloblastoma (MB) is the most common malignant pediatric brain tumor arising in the cerebellum or the 4th ventricle
Of 968 patients diagnosed with primary MB, 15 patients had MBs located in the Cerebellopontine angle (CPA) (Table 1)
Based on the pre- and postoperative MRI results and intraoperative reports, we found that all WNT-MBs were derived from the brainstem (P = 0.004) and grew exclusively outside the cerebellum, whereas SHH-MBs resided in the cerebellar hemispheres (P = 0.002; Fig. 1; Table 2)
Summary
We retrospectively reviewed a cohort of 968 patients with a final pathological diagnosis of MB at the Beijing Neurosurgical Institute between 2002 and 2016 that included 214 adult patients and 754 pediatric patients. Patients with both preoperative MRI data and surgical tissue available for molecular analysis were included. All tumor specimens were sterilely stored (frozen or formalin-fixed paraffin-embedded tissues) at the Beijing Neurosurgical Institute in accordance with the Ethics Review Board of the Beijing Tian Tan Hospital (study reference). All available follow-up data began from initial diagnosis until subsequent tumor progression, patient death, or the end of the last follow-up. PFS was defined as the time from the date of surgical resection until the date of tumor progression confirmed by imaging
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