Ependymal tumors

Question 1

Major divisions of ependymoma / ependymal tumors

Answer 1

By location:
1. Supratentorial
2. Posterior fossa
3. Spinal

Question 2

Supratentorial ependymal neoplasms

Answer 2

By morphology/genetics:
1. Subependymoma (morphology)
2. ZFTA fusion-driven
3. YAP1 fusion-driven

Question 3

Posterior fossa ependymal neoplasms

Answer 3

By morphology/methylation pattern:
1. Subependymoma (morphology)
2. Posterior fossa group A (defined by methylation, loss of H3 K27me3, rarely EZHIP mutations)
3. Posterior fossa group B (defined by methylation, retention of H3 K27me3, chromosomal instability)

Question 4

Spinal ependymal neoplasms

Answer 4

By morphology and gene amplification:
1. Subependymoma (morphology)
2. Spinal ependymoma,MYCN amplified
3. Classic ependymoma (morphology)
4. Myxopapillary ependymoma (morphology)

Question 5

Answer 5

Supratentorial ependymoma

You must EXCLUDE YAP1 or ZFTA fusions in order to make this diagnosis.

Circumscribed supratentorial glioma that focally demonstrates pseudorosettes (perivascular anculeate zones) or true ependymal rosettes and comprises uniform small cells with round nuclei embedded in a fibrillary matrix. Hyalinization of blood vessels and calcification are frequent. A vascular pattern seen in supratentorial ependymomas, but not other ependymal tumours, manifests as a branching network of capillary blood vessels.

IHC: OLIG2 negative, GFAP positive, EMA positive (perinuclear dot-like and along the surface of ependymal rosettes)

Question 6

Answer 6

Posterior fossa ependymoma

Question 7

Answer 7

Myxopapillary ependymoma

One of the subtypes of spinal ependymoma

CNS WHO grade 1