Diffuse Leptomeningeal Glioneuronal Tumour: Molecular Diagnosis, Evolution and Treatment

Diffuse leptomeningeal glioneuronal tumour (DLGNT) is rare a glioneuronal neoplasm of the central nervous system, which occurs mainly in children and adolescents characterized by the presence of MAPK pathway alteration and 1p deletion. Clinical, radiological and molecular data from 20 patients diagnosed with DLGNT from May 2001 to May 2023 were collected. Clinical presentation was polymorphous, with intracranial hypertension and back pain as most common symptoms. Patients underwent multiple lines of treatment (median of 4, range 1-8) in addition to surgery with a median follow up of 94 months (range 7–241). Radiotherapy and carboplatin-based chemotherapy were the 2 treatments with the higher number of partial response (PR) and stable disease (SD) of 7/10 and 2/10 for radiotherapy and 7/12 and 5/12 for carboplatin-based chemotherapy. All patients treated with trametinib progressed before 2 years, while 2-years PFS was of 52% (95% CI 20-77%), for carboplatin-based chemotherapy, 40% (95% CI 10-70%) for radiotherapy, 29% (95% CI 9-53%) for Temozolomide and 13% (95% CI 1-42%) for Vinblastine/Vinorelbine. Neurological sequelae concerned 70% of patients with at least on neurological impairment at last follow-up. In total, 7 patients died including 5 from disease progression. The 5-years and 10-years OS were of 88% (95% CI 59-97%) and 78% (95% CI 45-93%) respectively. Our work reports the outcome and treatment response of a retrospective cohort of DLGNT. Close monitoring appears to be the key to early treatment initiation and limiting patient disability. Further prospective studies in multi-institutional cohorts are needed to better define a standardized treatment approach.