Diffuse Leptomeningeal Glioneuronal Tumor of Childhood

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.

Glioneuronal Tumors: Insights into a Rare Tumor Entity

“…DLGNT was added to the WHO classification in 2016 and publications have increased since (1,2,(45)(46)(47)(48)(49)(50)55). In DLGNT, MRI is generally consistent with diffuse leptomeningeal enhancement predominantly and multiple cystic-solid lesions along the neural axis (49,59,87) but may present more atypically as well (45,88). GGs appear cystic-solid or solid with long T1 and T2 signals with associated calcification (89).…”

Imaging of brain tumors in children: the basics—a narrative review

“…On MRI, this tumor often presents as diffuse intracranial and intraspinal lesions with nodular/thick leptomeningeal appearance and avid enhancement extending over the basal cisterns and brain and spinal surfaces. Presence of microcysts/nonenhancing small cyst-like lesions and dilation of perivascular spaces are commonly observed (3,(74)(75)(76). Less frequently, non typical features, such as isolated spinal cord or brain lesions without clear leptomeningeal involvement, can be found (76).…”

“…Presence of microcysts/nonenhancing small cyst-like lesions and dilation of perivascular spaces are commonly observed (3,(74)(75)(76). Less frequently, non typical features, such as isolated spinal cord or brain lesions without clear leptomeningeal involvement, can be found (76). The main differential diagnosis includes inflammatoryinfection entities, particularly those that often show signs of meningitis with diffuse leptomeningeal enhancement, cisternal involvement, and hydrocephalus such as tuberculosis (77).…”

The Pediatric Spine

“…More common in children than in adults, diffuse leptomeningeal glioneuronal tumor (WHO 2016) 45 represents a leptomeningeal disease even in the absence of direct involvement of the spinal cord (or other parenchymal involvement). It may appear "multinodular" and "vacuolated" with variable prognosis (slow growth but with dissemination).…”

“…44 In this context, it is possible to observe T2-hyperintense nodules (or cystic nodule) with diffuse enhancement of the leptomeninges. 45 Differential diagnosis includes carcinomatosis and infection.…”