Cutaneous melanoma is an aggressive form of human skin cancer characterized by high metastatic potential and poor prognosis. To better understand the role of microRNAs (miRNAs) in melanoma, the expression of 470 miRNAs was profiled in tissue samples from benign nevi and metastatic melanomas. We identified 31 miRNAs that were differentially expressed (13 upregulated and 18 down-regulated) in metastatic melanomas relative to benign nevi. Notably Cutaneous melanoma is a form of skin cancer characterized by aggressive metastatic growth and poor prognosis. 1 The incidence of melanoma continues to increase in many parts of the world.2 The median survival time of patients with metastatic melanoma is 6 months, and the 5-year survival rate is less than 5%.3 Genetic factors and exposure to ultraviolet radiation are risk factors for melanoma pathogenesis.4

Cell block sections had more successful ISH-EBER assays when compared with cytospins. Reasons for failure were loss of material on the slide and background staining. A high concordance rate with surgical specimens emphasizes the usefulness of cytological samples for determining EBV status in patients with exhausted or no histological material available.

We report the cases of 3 patients with fatal, disseminated Mycobacterium chimaera infections following cardiac surgeries. Progressive neurocognitive decline and death were explained by active granulomatous encephalitis, with widespread involvement of other organs. This syndrome is clinically elusive and, thus, may have caused deaths in prior reported series.

neuropathology practice and the access of different centres to these tests, we designed a survey that was sent to all members of the Canadian Association of Neuropathology member list in the fall of 2017. This survey asked a number of questions relating to the approach to glioma diagnosis, immunohistochemical/ molecular test ordering patterns, in-house test availability, and need to send out for testing. In this presentation we will present preliminary results from this survey, with a focus on institutional testing capabilities. This provides a valuable resource that could ultimately need to a national database of immunohistochemical and molecular test availability for each neuropathology centre. LEARNING OBJECTIVESThis presentation will enable the learner to:1. Review the key molecular markers in the diagnosis of adult gliomas and methods of testing for them 2. Discuss the effect that the 2016 WHO CNS tumor update has had on clinical practice in Canada ABSTRACT 14Role of MacroH2A2 in the glioblastoma stem cell epigenome Glioblastoma is the most common primary malignant brain tumour in adults, and remains uniformly lethal. These tumours contain a subpopulation of glioblastoma stem cells (GSCs) that drive tumour recurrence and drug resistance. We find that MacroH2A2 is a histone variant that can stratify glioblastoma patients, with higher levels of this histone variant associated with better patient prognosis. Knockdown of macroH2A2 in GSCs is associated with increased self-renewal and an increased expression of stemness genes by RNA-seq. Our preliminary results suggest that macroH2A2 is a novel biomarker for glioblastoma and that macroH2A2 loss is a marker of GSC stemness and a poor prognostic marker in glioblastoma. This work identifies loss of macroH2A2 as a feature of GSCs and provides a framework for therapeutic modulation of this histone variant. LEARNING OBJECTIVESThis presentation will enable the learner to: 1. Explain the role of epigenetics in glioblastoma pathophysiology ABSTRACT 15 Cerebellar glioblastoma: a clinicopathologic series of 16 cases This presentation will enable the learner to: 1. Identify the clinicopathological features of cerebellar GBMs including major molecular alterations 2. Compare cerebellar and supratentorial GBMs and describe the distinguishing features of each type of tumor SESSION 4: Infectious/Immune mediated Neuropathology and Neuromuscular Neuropathology ABSTRACT 16Mycobacterium chimaera encephalitis following cardiac surgery in three adult immunocompetent patients: first detailed neuropathological report.