Abstract
Diffuse leptomeningeal glioneuronal tumor is a newly defined entity under the neuronal and mixed neuronal-glial tumors category in the 2016 World Health Organization classification of brain tumors. In this series, we report clinical, radiologic, and histologic findings in 7 cases of diffuse leptomeningeal glioneuronal tumor. Our cases and literature review indicate that the most characteristic imaging finding is diffuse intracranial and intraspinal nodular leptomeningeal thickening and enhancement. This is often associated with small cyst-like, nonenhancing lesions. It should be noted that tumors sometimes bear nontypical features, for example, presenting as a solitary spinal cord mass without leptomeningeal involvement or with a dominant intracranial mass. In children with characteristic imaging findings and without clinical features of infection, the radiologist has an opportunity to promptly raise the possibility of diffuse leptomeningeal glioneuronal tumor, and thereby, affect streamlined diagnostic evaluation.
Highlights
All patients underwent in the radiology literature to date. This is important because brain and spinal cord imaging at either 1.5 or 3T with the follow- many tumors previously classified otherwise are known to postgadolinium T1-weighted, and diffusion-weighted
Given the recent changes in classification by the World Health Organization (WHO), as well as the rarity of this neoplasm, many radiologists may not yet be aware of Diffuse leptomeningeal glioneuronal tumor (DL-GNT). This condition may be unexpected by referring clinicians caring for patients with a newly discovered leptomeningeal disease process
In recognizing the various imaging patterns illustrated in this series, the radiologist may be the first member of the clinical team to suspect this rare diagnosis
Summary
Institutional review board approval was waived and not required for this retrospective case series. On MR imaging, diffuse nodular intracranial leptomeningeal thickening was present in 5 of 7 (72%) cases (On-line Table 1, Fig 1A, -B). Multiple intracranial lesions that did not enhance or suppress on FLAIR (“cystic-appearing”) were noted in 2 of. 7 (29%) cases (On-line Table 1, Fig 2A). A dominant intracranial parenchymal mass lesion was noted in 1 of 7 (15%) cases (On-line Table 1, Fig. 3A-C). The patterns of spinal involvement included: diffuse, dorsalpredominant nodular leptomeningeal thickening 1 patient with cysticappearing spinal cord lesions and another patient with a large intramedullary mass were the ones without associated nodular leptomeningeal spinal disease. All the cases underwent biopsy and histopathologic analysis. These cyst-like lesions are very suggestive of DL-GNT
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