cne21th

Subependymoma

Definition
A slowly growing, benign neoplasm, typically attached to a ventricular wall, composed of glial tumour cell clusters
embedded in an abundant fibrillary matrix with frequent microcystic change.

Grading :
WHO grade I.

Localization:
Most frequent: fourth ventricle (50-60% of cases), then the lateral ventricles (30-40%), less third ventricle and septum pellucidum.
Spinal cord, cervical and cervico-thoracic intramedullary or, rarely, extramedullary mass lesions.

Histopathology:
Characterized by clusters of isomorphic nuclei embedded in a dense fibrillary matrix of glial cell processes with frequent occurrence of small cysts.
Mitoses are rare or absent.
In solid tumours, occasional pleomorphic nuclei may be encountered.
Calcifications and haemorrhage can occur.
Cell processes are oriented around vessels, thus forming ependymal pseudorosettes.

Immunoprofile:
GFAP (+), Ki-67 < 1%

Prognostic and predictive factors:
Neoplasms with a mixed ependymoma and subependymoma morphology appear to follow a clinical course corresponding to the ependymoma component (WHO grades II-III).