Rosette-forming and papillary glioneuronal tumors - A clinicopathological and molecular analysis

Introduction: Rosette-forming glioneuronal tumors (RGNT) and papillary glioneuronal tumors (PGNT) account for < 1% of brain tumors. Genetic data regarding RGNT and PGNT is still evolving. We aimed to perform a detailed clinicopathological analysis on rosette-forming and papillary glioneuronal tumors and to evaluate these for common, known genetic mutations. Materials and methods: Our cohort consisted of 6 cases of these rare glioneuronal tumors diagnosed over a period of 5 years. IDH1, ATRX, p53, and BRAF V600E mutations were evaluated on immunohistochemistry, and cases of RGNT were screened for the mutations in PIK3CA gene at hotspots exon 4, 9, and 20. Results and conclusions: Our findings confirm the presence of PIK3CA gene mutations in RGNT along with two novel mutations in PIK3CA gene, of which one is proposed to be of prognostic significance.