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Journal of Clinical Pathology and Laboratory Medicine | Volume 3
July 05-06, 2019 | Paris, France
Pathology and Surgical Pathology
2
nd
International Conference on
An overall view of the new genetic developments that changed the classification of
tumours of central nervous system
Ana Maria C Tsanaclis and F Berthelet
University of Montreal School of Medicine, Canada
T
he last WHO classification of tumours of the nervous
system of 2016 stresses the importance of genetic
alterations that permitted the inclusion of new diagnostic
categories. This is the case of tumours of the diffuse astrocytic
type: Identification of mutations in the genes IDH-1 and IDH-
2, either by immunohistochemistry or by genetic evaluation
of mutations are important tools that have prognostic
implications. A new entity has been added to this group
with mutation of the H3K27M gene – diffuse midline glioma.
The diagnosis of an oligodendroglial tumour needs the
presence of co-deletions of the chromosomes 1p and 19q
and mutation of the IDH-1 gene. Deletions or translocations
resulting in BRAF fusion proteins are pathognomonic of
pilocytic astrocytomas; Mutation of the FGFR1 are found in
midline pilocytic astrocytomas. Many molecular alterations
have been described in the ependymoma group: Cytogenetic
aberrations, fusion genes involving the RELA or YAP1 genes
are found in supratentorial ependymomas whereas for the
spinal cord group present with genome wide polyploidy.
These characteristics have prognostic implications. MGMT
promoter methylation was described in all choroid plexus
papilloma and mutations of the TP53 gene was found in
almost all choroid plexus carcinoma and those exhibiting
loss of the chromosome 12q are associated to a shorter
survival. MYCN gain and overexpression of genes of the WNT
signaling pathway were described in central neurocytomas.
Medulloblastomas may be genetically or histologically
defined with important prognostic implications. Finally,
inversion on chromosome 12q13 generates the fusion of
the NAB2 et STAT6 genes and induces the nuclear expression
of STAT6 necessary for the diagnosis of the solitary fibrous
tumour/hemangiopericytoma. Since 2016 a number of new
genotype varieties of tumours of the central nervous system
have been added.
e
:
amctsana@hotmail.com