Myxoid glioneuronal tumor
Citation, DOI and article data
Myxoid glioneuronal tumor is a rare and low-grade tumor (WHO grade 1) that usually involve the septum pellucidum, corpus callosum, subcallosal area, periventricular white matter and septal nuclei 1.
The histologic features of this tumor are similar to dysembryoplastic neuroepithelial tumor (DNET) and therefore they were formerly called "DNET of the septum pellucidum" 2.
In 2020 cIMPACT-NOW Working Committee considered it as a distinct entity based on genetic mutations, imaging features and anatomic location, named "Myxoid glioneuronal tumor, PDGFRA p.K385- mutant" 3 and it is included in the 5th Edition (2021) WHO brain tumor classification 5.
It often occurs in children and young adults. It represents about 2% of all brain tumors 3.
Although it has been designated as a WHO grade 1 tumor in the current WHO brain tumor classification, it tends to recur, progress or disseminate in the ventricles. They may cause critical mass and compressive effect with obstructive hydrocephalus 1.
This tumor demonstrates a low-grade proliferation of oligodendrocyte-like tumor cells and a prominent myxoid/mucin-rich stroma. It is present a fine capillary network reminiscent of DNET or oligodendroglioma. It may show neurocytic rosettes 1.
Myxoid glioneuronal tumor is negative to BRAF and FGFR1 mutations or rearrangements, which distinguish DNETs, rosette-forming glioneuronal tumors (RGNTs) and other low-grade neuroepithelial tumor. Ki-67 index ranges from 1% to 4% 1.
This tumor has a well-defined lobulated mass appearance.
- T1: hypointense
- T2: hyperintense
- FLAIR: bright rim sign, like DNETs 4
- T1 C+ (Gd): no enhancement
Treatment and prognosis
Data regarding prognosis are limited given the rarity of this tumor. Surgical resection is often curative, although cases of recurrence, progression and intraventricular dissemination have been described. In these cases a second resection was frequently necessary. Seldom radiotherapy and chemotherapy have been used 1.
General imaging differential considerations include:
- 1. Lucas C, Villanueva-Meyer J, Whipple N et al. Myxoid Glioneuronal Tumor, PDGFRA P.K385-Mutant: Clinical, Radiologic, and Histopathologic Features. Brain Pathol. 2020;30(3):479-94. doi:10.1111/bpa.12797 - Pubmed
- 2. Baisden B, Brat D, Melhem E, Rosenblum M, King A, Burger P. Dysembryoplastic Neuroepithelial Tumor-Like Neoplasm of the Septum Pellucidum: A Lesion Often Misdiagnosed as Glioma: Report of 10 Cases. Am J Surg Pathol. 2001;25(4):494-9. doi:10.1097/00000478-200104000-00009 - Pubmed
- 3. Louis D, Wesseling P, Aldape K et al. CIMPACT-NOW Update 6: New Entity and Diagnostic Principle Recommendations of the CIMPACT-Utrecht Meeting on Future CNS Tumor Classification and Grading. Brain Pathol. 2020;30(4):844-56. doi:10.1111/bpa.12832 - Pubmed
- 4. Narvaez E, Inada B, de Almeida P et al. Myxoid Glioneuronal Tumour – Report of Three Cases of a New Tumour in a Typical Location and Review of Literature. BJR|case Reports. 2021;7(4):20200139. doi:10.1259/bjrcr.20200139
- 5. Louis D, Perry A, Wesseling P et al. The 2021 WHO Classification of Tumors of the Central Nervous System: A Summary. Neuro Oncol. 2021;23(8):1231-51. doi:10.1093/neuonc/noab106 - Pubmed