Unusual high-grade features in pediatric diffuse leptomeningeal glioneuronal tumor: comparison with a typical low-grade example

• Published in: Human pathology 2017-12, Vol.70, p.105-112
• Main Authors: Schwetye, Katherine E., Kansagra, Akash P., McEachern, James, Schmidt, Robert E., Gauvain, Karen, Dahiya, Sonika
• Format: Article
• Language: English
• Subjects: Biomarkers, Tumor - analysis; Biomarkers, Tumor - genetics; Child; Chromosome Deletion; Chromosomes, Human, Pair 1; Chromosomes, Human, Pair 19; Classification; Diffuse; Diffusion Magnetic Resonance Imaging; Fatal Outcome; Gene Duplication; Gene Rearrangement; Genetic Predisposition to Disease; Glioneuronal; Humans; Immunohistochemistry; Leptomeningeal; Male; Meningeal Neoplasms - diagnostic imaging; Meningeal Neoplasms - genetics; Meningeal Neoplasms - pathology; Meningeal Neoplasms - therapy; Mitotic Index; Molecular Diagnostic Techniques; Mutation; Neoplasm Grading; Neuroglia - chemistry; Neuroglia - pathology; Neurons - chemistry; Neurons - pathology; Neuropathology; Pediatric; Pediatrics; Phenotype; Proto-Oncogene Proteins B-raf - genetics; Treatment Outcome; Tumor; Tumors
• ISSN: 0046-8177; 1532-8392
• DOI: 10.1016/j.humpath.2017.06.004

Diffuse leptomeningeal glioneuronal tumor, a recent addition to the World Health Organization classification system, typically presents in the pediatric population with signs and symptoms related to elevated intracranial pressure and imaging characteristics that may mimic infectious etiologies. The tumor is usually low grade and tends to harbor BRAF rearrangement/duplication in up to 75% of cases, BRAF V600E mutation in a smaller subset of cases, and loss of chromosomal arm 1p in approximately 50%-60% of cases, with ~20% of those showing loss of both 1p and 19q (codeletion). We report here 2 contrasting cases of diffuse leptomeningeal glioneuronal tumors, one with typical low-grade features and an indolent, although not benign, course, in which the disease is currently successfully managed by chemotherapy, and a second case with unusually high-grade features on initial presentation, including frank anaplasia and elevated mitotic index, in which the disease showed an initial response to chemoradiation but ultimately was fatal. •Report of a pediatric high-grade diffuse leptomeningeal glioneuronal tumor.•Compared with a low-grade diffuse leptomeningeal glioneuronal tumor, including clinical, radiologic, and treatment details.•High-grade tumor lacked BRAF rearrangement, and BRAF V600E and H3.3 K27M variants.