Primary leptomeningea presentation of tumors with diffusion restriction. Report of two cases

Abstract

Primary leptomeningeal tumors in pediatrics are uncommon entities. They mostly consist of diffuse glioneuronal tumors, although a few cases of embryonal tumors have also been reported. The complexity in diagnosing this presentation is due to atypical clinical manifestations and difficulties in the differential diagnosis. Diffusion-weighted imaging (DWI) is an imaging modality that is extremely sensitive in detecting water movement in the extracellular space . In neuro-oncology, its utility lies in differentiating between tumors with low cellular density and those with high cellular density, particularly those composed of “small, round, and blue” cells. In this study, we present two cases of disseminated primary leptomeningeal tumors of embryonal origin without a primary brain mass, showing restriction on DWI (hypercellularity). The cases, studied at Garrahan Hospital in the last 3 years, along with a literature review, indicate that the most common imaging finding is diffuse intracranial and intra-spinal leptomeningeal nodular thickening and enhancement. However, no reports were found on the utility of DWI in diagnosing these entities. The article analyzes neuroimaging approaches and diagnostic confirmation to provide opportunities for effective treatment of these diseases in clinical practice.