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Background: Malignant change in vestibular schwannoma is rare and intracranial metastatic deposits have not been reported., Clinical Presentation: We report the case of a 64 year old woman with a benign vestibular schwannoma who underwent translabyrinthine excision in 1996 and Gamma Knife ® radiosurgery (Elekta AB, Stockholm, Sweden) (GKRS) in 2006. She presents 10 years after GKRS with progressive neurological deterioration. Histopathologic analysis confirms a malignant peripheral nerve sheath tumour, WHO grade IV with subsequent metastatic spread to the left thalamus confirmed on biopsy., Conclusion: We report a rare case of a vestibular schwannoma metastasizing with histological confirmation. It also reminds us of malignant conversion of a benign vestibular schwannoma following GKRS and subsequent aggressive behaviour, with poor prognosis.

Introduction: A retrospective study over a three-year period at University Hospital of Wales (UHW) of the incidence of atypical cranial grade II meningioma both pre and post 2016 revision of The World Health Organisation (WHO) classification of tumours of the central nervous system. Subjects: All available histology from January 2015 to December 2017 of patients with cranial meningiomas. Method: Institutional online reporting system Welsh Clinical Portal to identify patients and view histology reports. Results: Overall 164 patient histology results were analysed (median age 59, age range 23-82, 74% females). There were 55 patients in 2015: 69.1% grade I, 29.1% grade II and 1.8% grade III. There were 109 patients in 2016/17; 68.8% grade I, 29.4% grade II, 1.8% grade III. Discussion: There is significant variability in the reported incidence of grade II meningioma, likely due to variation in local interpretation of diagnostic criteria. Neuropathologists at our institution have reported brain invasion as grade II prior to 2016. This was due to compelling published evidence that brain invasive meningiomas have recurrence and mortality rates similar to that of grade II meningioma as defined using other criteria. The new 2016 WHO criteria now recognise this specifically. As other institutions adapt to the amended 2016 guidelines we anticipate that there will be a greater consensus in line with our incidence rates of grade II meningioma.

Pineal region lesions are uncommon, and pineal parenchymal tumours (PPT) account for 20-30% of tumours in this area of which pineocytomas (PCs) and pineoblastomas (PBs) are more prevalent. In 2007, the World Health Organisation (WHO) reclassified PPT from two subgroups (PC and PB) into four, including pineal parenchymal tumours of intermediate differentiation (PPTID). PPTID have been further divided into low- and high-grade lesions (WHO II and III), but due to their rarity have proven difficult lesions to diagnose and a paucity of literature means their optimal treatment options are a challenge to define. This article is a review of the literature of PPTID highlighting diagnostic criteria, a discussion on the role of surgery and radiotherapy, including treatment paradigms and reported outcomes for these problematic neoplasms.