Molecularly defined diffuse leptomeningeal glioneuronal tumor (DLGNT) comprises two subgroups with distinct clinical and genetic features

Maximilian Y. Deng, Martin Sill, Jason Chiang, Jens Schittenhelm, Martin Ebinger, Martin U. Schuhmann, Camelia Maria Monoranu, Till Milde, Andrea Wittmann, Christian Hartmann, Clemens Sommer, Werner Paulus, Jutta Gärtner, Wolfgang Brück, Thomas Rüdiger, Alfred Leipold, Zane Jaunmuktane, Sebastian Brandner, Felice Giangaspero, Paolo NozzaJaume Mora, Andres Morales la Madrid, Ofelia Cruz Martinez, Jordan R. Hansford, Torsten Pietsch, Anna Tietze, Pablo Hernáiz-Driever, Iris Stoler, David Capper, Andrey Korshunov, David W. Ellison, Andreas von Deimling, Stefan M. Pfister, Felix Sahm, David T.W. Jones

Research output: Contribution to journalArticle

Abstract

Diffuse leptomeningeal glioneuronal tumors (DLGNT) represent rare CNS neoplasms which have been included in the 2016 update of the WHO classification. The wide spectrum of histopathological and radiological features can make this enigmatic tumor entity difficult to diagnose. In recent years, large-scale genomic and epigenomic analyses have afforded insight into key genetic alterations occurring in multiple types of brain tumors and provide unbiased, complementary tools to improve diagnostic accuracy. Through genome-wide DNA methylation screening of > 25,000 tumors, we discovered a molecularly distinct class comprising 30 tumors, mostly diagnosed histologically as DLGNTs. Copy-number profiles derived from the methylation arrays revealed unifying characteristics, including loss of chromosomal arm 1p in all cases. Furthermore, this molecular DLGNT class can be subdivided into two subgroups [DLGNT methylation class (MC)-1 and DLGNT methylation class (MC)-2], with all DLGNT-MC-2 additionally displaying a gain of chromosomal arm 1q. Co-deletion of 1p/19q, commonly seen in IDH-mutant oligodendroglioma, was frequently observed in DLGNT, especially in DLGNT-MC-1 cases. Both subgroups also had recurrent genetic alterations leading to an aberrant MAPK/ERK pathway, with KIAA1549:BRAF fusion being the most frequent event. Other alterations included fusions of NTRK1/2/3 and TRIM33:RAF1, adding up to an MAPK/ERK pathway activation identified in 80% of cases. In the DLGNT-MC-1 group, age at diagnosis was significantly lower (median 5 vs 14 years, p < 0.01) and clinical course less aggressive (5-year OS 100, vs 43% in DLGNT-MC-2). Our study proposes an additional molecular layer to the current histopathological classification of DLGNT, of particular use for cases without typical morphological or radiological characteristics, such as diffuse growth and radiologic leptomeningeal dissemination. Recurrent 1p deletion and MAPK/ERK pathway activation represent diagnostic biomarkers and therapeutic targets, respectively—laying the foundation for future clinical trials with, e.g., MEK inhibitors that may improve the clinical outcome of patients with DLGNT.

Original languageEnglish
Pages (from-to)239-253
Number of pages15
JournalActa Neuropathologica
Volume136
Issue number2
DOIs
Publication statusPublished - Aug 1 2018

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Keywords

  • Brain tumor
  • Diffuse leptomeningeal glioneuronal tumor
  • Methylation
  • Pediatric
  • Prognostic
  • Subgroup

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Clinical Neurology
  • Cellular and Molecular Neuroscience

Cite this

Deng, M. Y., Sill, M., Chiang, J., Schittenhelm, J., Ebinger, M., Schuhmann, M. U., Monoranu, C. M., Milde, T., Wittmann, A., Hartmann, C., Sommer, C., Paulus, W., Gärtner, J., Brück, W., Rüdiger, T., Leipold, A., Jaunmuktane, Z., Brandner, S., Giangaspero, F., ... Jones, D. T. W. (2018). Molecularly defined diffuse leptomeningeal glioneuronal tumor (DLGNT) comprises two subgroups with distinct clinical and genetic features. Acta Neuropathologica, 136(2), 239-253. https://doi.org/10.1007/s00401-018-1865-4