Ependymal tumors classification [Neurosurgery Wiki]

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== Ependymal tumors classification ======


  [[Supratentorial ependymoma]] 

  [[Supratentorial ependymoma ZFTA fusion-positive]] 

  [[Supratentorial ependymoma YAP1 fusion-positive]] 

  [[Posterior fossa ependymoma]]
 
  [[Posterior fossa ependymoma group PFA]] 

  [[Posterior fossa ependymoma group PFB]] 

  [[Spinal ependymoma]] 

  [[Spinal ependymoma MYCN-amplified]] 

  [[Myxopapillary ependymoma]] 

  [[Subependymoma]] 

===== Old classification =====


[[Subependymoma]] 9383/1 WHO grade I

[[Myxopapillary ependymoma]] 9394/1 WHO grade I

[[Ependymoma]]

--[[Papillary ependymoma]] 9393/3 (WHO grade II)

--[[Clear cell ependymoma]] 9391/3 (WHO grade II)

--[[Tanycytic ependymoma]] 9391/3

[[Ependymoma RELA fusion positive]] 9396/3

[[Anaplastic ependymoma]] 9392/3 (WHO grade III).
----
According to the WHO classification, ependymal tumors are classified as subependymomas, myxopapillary ependymomas, classic ependymomas, anaplastic ependymomas, and RELA-fusion-positive ependymomas (RELA-EPN). Among classic ependymomas, the WHO defines rare histological variants, i.e., the clear cell, papillary, and tanycytic ependymoma. In parallel, global DNA methylation patterns distinguish nine molecular groups, some of which tightly overlap with histopathological subgroups. However, the match of the aforementioned histological variants to DNA methylation classes remains unclear. 

Neumann et al. analyzed histomorphology, clinical parameters, and global [[DNA methylation]] of tumors with the initial histological diagnoses of tanycytic (n = 12), clear cell (n = 14), or papillary ependymoma (n = 19). Forty percent of these tumors did not match to the epigenetic profile of [[ependymoma]]s, using a previously published DNA methylation-based classifier for brain tumors. Instead, they were classified as low-grade glioma (n = 3), plexus tumor (n = 2), CNS high-grade neuroepithelial tumor with MN1 alteration (n = 2), papillary tumor of the pineal region (n = 2), neurocytoma (n = 1), or did not match to any known brain tumor methylation class (n = 8). Overall, the integrated diagnosis had to be changed in 35.6% of cases as compared to the initial diagnosis. Among the tumors molecularly classified as ependymoma (27/45 cases), tanycytic ependymomas were mostly located in the spine (5/7 cases) and matched to spinal or myxopapillary ependymoma. 6/8 clear cell ependymomas were found supratentorial and fell into the methylation class of RELA-EPN. Papillary ependymomas with a positive ependymoma match (12/19 cases) showed either a "papillary" (n = 5), a "trabecular" (n = 1), or a "pseudo-papillary" (n = 6) growth pattern. The papillary growth pattern was strongly associated with the methylation class B of posterior fossa ependymoma (PFB, 5/5 cases) and tumors displayed DNA methylation sites that were significantly different when compared to PFB ependymomas without papillary growth. Tumors with pseudo-papillary histology matched to the methylation class of myxopapillary ependymoma (4/6 cases), whereas the trabecular case was anatomically and molecularly a spinal ependymoma. Our results show that the diagnosis of histological ependymoma variants is challenging and epigenetic profiles may improve diagnostic accuracy of these cases. Whereas clear cell and papillary ependymomas display correlations between localization, histology, and methylation, tanycytic ependymoma does not represent a molecularly distinct subgroup
((Neumann JE, Spohn M, Obrecht D, Mynarek M, Thomas C, Hasselblatt M, Dorostkar 
MM, Wefers AK, Frank S, Monoranu CM, Koch A, Witt H, Kool M, Pajtler KW,
Rutkowski S, Glatzel M, Schüller U. Molecular characterization of
histopathological ependymoma variants. Acta Neuropathol. 2019 Nov 2. doi:
10.1007/s00401-019-02090-0. [Epub ahead of print] PubMed PMID: 31679042.
)).