PATH-56. SUPRATENTORIAL NEUROEPITHELIAL TUMORS WITH NOVEL PLAGL1 FUSIONS: 2 CASE REPORTS

Abstract

Abstract Neuroepithelial tumors with pleomorphic adenoma gene-like (PLAGL1) fusions represent a distinct subgroup of neoplasms that have been recently identified. These fusions are quite rare and most commonly associated with fusions in the EWSR1 or FOXO1 genes. Limited reports in literature have indicated a median age of diagnosis of 6.2 years and poor progression-free survival at 35 months. Here we present two cases of patients with neuroepithelial tumors with PLAGL1 fusions. Case 1 was a 49 year old male who underwent resection of a left frontal lobe mass at 2 year old that was reported as a low grade ependymoma. He did not receive radiation or chemotherapy and subsequently developed seizures in childhood. At age 47, he presented with worsening seizures and MRI brain revealed a 4.5 cm mass in the left frontal lobe with serpiginous enhancement. He underwent surgical resection and molecular profiling demonstrated PLAGL1-FOXO1 fusion. Case 2 was an 18 year old female presenting with generalized tonic-clonic seizures. MRI brain demonstrated a 1.4 x 1.2 cm cortical and subcortical lesion in the right parietal lobe. Following surgical resection, pathology reported a low grade neuroepithelial neoplasm with ependymal-like features. Molecular profiling showed PLAGL1-EWSR1 fusion. As PLAGL1 fusions are not yet characterized in the WHO classification system, these cases aid in tumor characterization and highlight the importance of molecular and methylation analysis for accurate tumor classification. Case 2 presents a notable variation from reported age of presentation of 6.2 years with diagnosis at 18 years of age, indicating these tumors may also present in young adulthood. Additionally, Case 1 demonstrated 45 years progression-free survival compared to previously reported median of 35 months, suggesting outcomes may be heterogeneous with potential for prolonged survival. Further research is needed to better elucidate the imaging, clinical course, and prognosis for tumors with this novel fusion.