WHO CNS 2016 TUMORS

MODERATORS: PROF.P. SARAT CHANDRA DR.RAMESH DODAMANI

PRESENTED BY: DR. JASKARAN SINGH

WHO GRADE CRITERIA

I Special circumscribed tumors

II Cytological atypia alone

III anaplasia and mitotic activity

IV Endothelial proliferation and necrosis

CATEGORIES

CATEGORIES

WHO CNS 2016 TUMORS

WHO CNS 2016 TUMORS

ATRX loss

DIFFUSE GLIOMAS

OLIGODEDROGLIOMA• Diagnosis of oligodendroglioma and anaplastic oligodendroglioma

requires demonstration of an IDH mutation and 1p/19q co-deletion

• Oligodendroglioma is now essentially defined by a particular genetic phenotype

DIFFUSE ASTROCYTOMA• 3 categories:

– IDH-mutant: Majority of grade II and III diffuse astrocytomas– IDH-wildtype– NOS : If IDH testing is not available or cannot be fully performed

• WHO grading remains the same, even though IDH-mutant cases have a more favorable prognosis

OLIGOASTROCYTOMA??• The use of term oligoastrocytoma is discouraged.

• Designated as NOS categories—should only be rendered in absence of diagnostic molecular testing or in the very rare instance of a dual genotype oligoastrocytoma.

Not tested Cannot be classified

NOS

GLIOBLASTOMA• 3 categories:

– Glioblastoma, IDH-wildtype ~90% of cases Most often corresponds to primary GBM– Glioblastoma, IDH-mutant ~10% of cases Most often corresponds to secondary GBM– Glioblastoma, NOS Reserved for tumors for which a full IDH evaluation cannot be performed

• Epithelioid GBM: new variant– Joins giant cell GBM and gliosarcoma– Predilection for children and young adults– BRAF V600E mutation– Lacks typical IDH-wildtype GBM molecular features (EGFR and LOH 10)– Associated low-grade precursor (?PXA)

• GBM with primitve neuronal component added as a pattern– Previously GBM with PNET-like component– Diffuse glioma (any grade) with well-demarcated nodules of primitve cells with neuronal differentiation (HW rosettes, synpa +, GFAP -)– MYC and MYCN amplification– CSF dissemination– ~25% origin from lower-grade glioma (IDHm)

• Variants deleted: – Protoplasmic astrocytoma – Fibrillary astrocytoma• Entities deleted: – Gliomatosis cerebri • Now a growth pattern of any diffuse glioma

2016: Diffuse Midline Glioma, H3 K27M mutant• New entity: earlier DIPG• Histology > Pediatric GBM = Adult GBM• Molecular > Pediatric GBM ≠ Adult GBM

This behaves as a Grade 4 tumor (GBM)

PEDIATRIC ASTROCYTOMAS• PXA or pilocytic-like methylation profiles (20%)

– Subset had BRAF V600E mutations– Good prognosis

• H3 K27M mutation (34%)– Midline location (including many diffuse intrinsic pontine gliomas)– Very poor prognosis

• IDH mutation (5%)– Good prognosis

OTHER ASTROCYTOMAS• Anaplastic PXA, WHO grade III – New entry – ≥ 5 mitoses / 10hpf; ± necrosis

• Pilomyxoid astrocytoma – grading redacted

EPENDYMOMAS • Present grading – questionable clinical utility• Addition: Ependymoma, RELA fusion–positive• Accounts for majority of supratentorial tumors in children.• RELA fusion: poor prognosis

MEDULLOBLASTOMAS• Generate an integrated

diagnosis that includes both the molecular group and histological phenotype.

• Classic

• Nodular

• Anaplastic

Other embryonal tumors• PNET deleted• Basis - amplification of the

C19MC region on chromosome 19 (19q13.42)• ETMR (embryonal tumors with

multilayered rosettes)• AT/RT- defined by alterations of

either INI1 or, very rarely, BRG1

Nerve sheath tumors• Melanotic schwannoma –

distinct entity

• Hybrid nerve sheath tumors

MPNST: 2 types

• Epithelioid MPNST • MPNST with perineurial

differentiation.

MENINGIOMA• Brain invasion as

criteria for atypical (Gr II) meningioma.

• Brain invasion• Mitotic count of 4 or more

• Spontaneous necrosis• Sheeting (loss of whorling or fascicular

architecture)• Prominent nucleoli• High cellularity• Small cells (tumor clusters with high

nuclear:cytoplasmic ratio).

Meningioma Grading: An Analysis of Histologic Parameters.Perry, Arie; Stafford, Scott; Scheithauer, Bernd; Suman, Vera; Lohse, ChristineAmerican Journal of Surgical Pathology. 21(12):1455-1465, December 1997.

(A) Brain invasion characterized by fingerlike or knobby protrusions into underlying cerebellar cortex. (B) No leptomeningeal layer is seen at the tumor-CNS interface.

SFT/HEMANGIOPERICYTOMA• STAT 6 nuclear expression: IHC

• Grade I: highly collagenous, relatively low cellularity, spindle cell lesion previously diagnosed as solitary fibrous tumor.• Grade II: more cellular, less collagenous tumor with plump cells and

“staghorn” vasculature that was previously diagnosed in the CNS as hemangiopericytoma.• grade III: anaplastic hemangiopericytoma in the past, diagnosed on the

basis of 5 or more mitoses per 10 high-power fields.

THANK YOU