Clinical responses of patients with diffuse leptomeningeal glioneuronal tumors to chemotherapy.

Introduction: Diffuse leptomeningeal glioneuronal tumors (DLGT) have been recognized in the most recent WHO classification as a distinct entity.

Objective: We describe seven pediatric cases of DLGT and the responses to therapy and outcome.

Methods: We conducted a retrospective review of charts from 1985 to 2013.

Results: DBS is an effective therapeutic modality for intractable TLE, particularly in patients with lateralized EEG A total of seven patients were identified. Median age at diagnosis was 3 years. Three months was the median time from symptom development to diagnosis. Common MRI findings included diffuse leptomeningeal thickening, nodularity, or coating of the subarachnoid or ependymal surfaces. The leptomeningeal lesions often appear cystic and contrast enhancement was variable. Six patients had leptomeningeal involvement of the brain and spine. All patients had a negative CSF cytology. Biopsies demonstrated thickened meninges infiltrated by a monotonous population of oligodendrocyte-like cells. Immunohistochemistry revealed variable features of neuronal and/or glial differentiation. All samples were negative for BRAF V600E mutation by immunohistochemistry. Therapy included one patient treated with craniospinal irradiation followed by vincristine, etoposide, cyclophosphamide, and cisplatin with stable disease for 164 months. Six patients received carboplatin and vincristine with a median duration of response of 20+ months (15-122+). Three patients received temozolomide upfront and progressed at 3, 4, and 27 months. No patients demonstrated complete or partial responses to any chemotherapy regimens. Progression-free survival ranged from 3 to 164+ months; 4/7 patients remained free of progression. All patients are alive.

Conclusions: DLGT are rare tumors that lack imaging responses; however, there was clinical/ symptom improvement in 100% of the patients. A better understanding of the tumor biology is necessary to improve the diagnosis and treatment of this rare disease.