Calcifications in diffuse leptomeningeal glioneuronal tumors: a case series

Diffuse leptomeningeal glioneuronal tumor (DLGNT) is a new rare entity, typically seen in the pediatric population. Classical neuroimaging features at clinical onset include marked subarachnoid/leptomeningeal enhancement and tiny pseudo-cystic lesions along the subpial surface of the neuroaxis, frequently associated with communicating hydrocephalus. However, data on the long-term appearance of this tumor on computed tomography (CT) and magnetic resonance imaging (MRI) are still lacking. We describe a peculiar pattern of progressive leptomeningeal calcifications in three young patients with DLGNT. The calcifications, mainly located in the basal cisterns, sylvian fissures and posterior surface of the thalami, were present at clinical onset in the older subject and appeared about 2 years after clinical onset in the other two. Patients underwent different schemes of chemotherapy, variably associated with craniospinal irradiation and/or bevacizumab. In all cases, calcifications were present before starting craniospinal irradiation and/ or treatment with bevacizumab. This novel peculiar pattern of progressive leptomeningeal calcifications expands the imaging phenotype of DLGNT and should be carefully sought, especially in later phases of the disease. Taking into consideration the onset, evolution, and absence of direct relationship with treatments, we hypothesize that calcifications in DLGNTs might be the effect of natural changes in the tumor and its environment.