Pediatric Oncology Education Materials

Ependymal central neuroepithelial cells during embryogenesis
Malignant degeneration of mature ependymal cells in the ventricular linings of subependymal zones of cellular proliferation.

Mature ependymal cells involved. Perivascular pseudorosettes and true ependymal rosettes are characteristic.

Glial fibrillary acidic protein (GFAP) expression is common.
In general, tumor cells are polygonal with large nuclei, clumped chromatin, small but distinct nucleoli and cytoplasm which extend into processes.

Roughly one third of this tumors are high grade (anaplastic ependymoma):

Summary of Histological Features of Ependymomas:

Location	Arise within or adjacent to the ependymal lining of the ventricular system or central canal of the spinal cord. Infratentorial ependymomas commonest in children. Spinal cord ependymomas usually occur in adults. Supratentorial ependymomas can occur in pediatric as well as adult patients
Macroscopic Appearance	Well-demarcated Soft grey-red tumors May be extensively cystic Calcifications
Microscopic Appearance	Well-delineated Moderately cellular tumor Polygonal cells Nuclei are generally uniform, moderately hyperchromatic and vary from round to oval Nucleoli are small but distinct. Cilia and blepharoblasts. Perivascular pseudorosettes. True ependymal rosettes Anaplastic features (little consensus on definition of reliable histopathological indicators of anaplasia). High cellularity, brisk mitotic activity, vascular proliferation and loss of perivascular rosettes (image 1)
Characteristic diagnostic feature	Perivascular pseudorosettes (image 2) Ependymal rosettes (image 3)

1. Anaplasia X200 - Anaplastic ependymoma with brisk mitotic activity and vascular proliferation.

2. Pseudorosettes X100 - Ependymoma with typical pseudorosettes characterized by nuclear free spaces around blood vessels.

3. Ependymal rosettes X200 - Ependymal rosettes.

Pediatric OncologyEducation Materials