BIOM-34. GENOMIC PROFILING IDENTIFIED COPY NUMBER VARIATIONS OF CDK4/6 AS A NOVEL PROGNOSTIC BIOMARKER FOR THALAMIC GLIOMA

BACKGROUND Thalamic glioma is a rare tumor, which is poorly understood in adults. The genetic variation of this tumor is still unknown. In this study, we investigated the mutation landscape of thalamic glioma and compared the clinical outcomes between different mutation situations in thalamic glioma. METHODS Next-generation sequencing targeting 425 cancer-relevant genes was performed with 34 thalamic glioma tissue samples. Gene mutations and copy number variations were investigated for prognostic effect with overall survival data. RESULTS Several diagnostic and prognostic biomarkers appeared in our thalamic glioma cohort, including TP53 (56%), EGFR (41%), TERT (35%), M CL1 (26%), PDGFRA (26%), PTEN (26%), CDK4/6 (24%), POLE (24%), PIK3CA (24%), NF1 (21%), ATR (21%), ATRX (18%), BRAF (15%), and ROS1 (12%). Among all genetic aberrations with a more than 10% occurrence rate, two mutations (TERT and PTEN) were associated with poor overall survival and one copy number variation (CDK4/6) was associated with favorable overall survival (univariate P < 0.1). Among these genes, CDK4/6 copy number variations (hazard ratio [HR], 0.16; 95% confidence interval [CI], 0.035–0.704; P = 0.016) remained significant survival associated in multivariate analyses. Copy number variations of CDK4/6 was seldom reported as a prognostic biomarker for glioma, especially for thalamic glioma in public databases. Besides, several gene mutations (BRIP1, MRE11A, MAP2K1, ROS1, MUTYH, JARID2, CTCF, and EGFR) were found positively associated with CDK4/6 copy number variations. Gene enrichment analysis demonstrated that those genes were related to astrocyte differentiation. CONCLUSIONS In our study, CDK4/6 copy number variation was determined as a favorable overall survival biomarker for thalamic glioma, and CDK4/6 copy number variation associated mutant genes were related to astrocyte differentiation, which could be the potential therapeutic targets for thalamic glioma.

The concept of “Four Walls, Two Poles” in the lesions of the thalamus and ganglion regions: case report and literature review

Background There are few articles about the surgical techniques of thalamic glioma and the lesions in the basal ganglia area. According to three existing cases and the literature review (Twelve articles were summarized which mainly described the surgical techniques), we discuss the surgical characteristics of lesions of the thalamus and basal ganglia area and summarize the relevant surgical skills. Case presentation Of the three cases, two were thalamic gliomas and one was brain abscess in basal ganglia. According to the three-dimensional concept of the “Four Walls, Two Poles”, lesions of the thalamus and basal ganglia were surgically removed, and the operative effect was analysed by relevant surgical techniques. Surgical resection of the lesions of the thalamus and basal ganglia area according to the three-dimensional concept of the “Four Walls, Two Poles” has achieved good surgical results. Relevant surgical techniques, such as the use of retractors, the use of aspirators, the choice of surgical approaches, and the haemostasis strategy, also played an important role in the operation process. Conclusions In the presented three cases the three-dimensional concept of the “Four Walls, Two Poles” allowed for safe surgical resection of lesions of the thalamus and basal ganglia.

Dejérine-Roussy syndrome associated with unilateral thalamic glioma

Context: Déjérine-Roussy Syndrome is a rare entity that occurs after an ischemia located in the ventral posterolateral nucleus, and it is characterized by hemiplegia, superficial hemianesthesia, mild hemiataxia and astereognosis, pain on the paretic side and choreoathetosis movements. This unusual condition can be caused by haemorrhage or neoplasm. Thalamic tumors make up less than 5% of all intracranial tumors. The rare clinical presentation of a thalamic tumor is a diagnostic and therapeutic challenge for neurology and neurosurgery practice and generally requires treatment without biopsy. Case report: A 54-years-old man presented complaining of burning and tingling paraesthesias, decreased sensitivity in left dimidium, associated with decreased visual acuity in the left eye. Physical examination showed complete left hemiparesis provided grade 4-, normoreflexia with athetoid movements of the left arm and hand, painful, thermal hemihipoesthesia and epicritic touch, allodyne in the left hemibody, pressure sensitivity present globally, visual campimetry by confrontation with heteronymous hemianopia without changes in the cranial nerves. Magnetic Resonance Imaging of the Skull Base showed an oval mass, with hyposignal in T1 and hypersignal in T2 and FLAIR, with peripheral contrast uptake in the thalamus and nuclei from the right base. The patient showed good clinical-surgical evolution after surgery with Glasgow Outcome Scale 4 and modified Rankin scale 2. Anatomical Pathology confirmed low-grade glioma. Conclusions: Early diagnosis and immediate therapy can delay a fatal outcome or decrease treatment-related morbidity.