Supratentorial ependymoma
General description
Supratentorial ependymomas are molecularly defined by either ZFTA (C11orf95)–RELA fusions or YAP1 fusions. ZFTA-rearranged tumors predominate in older children and adults, carry a less favorable prognosis, and display characteristic imaging of intraparenchymal, extra-ventricular masses with frequent calcification and heterogeneous enhancement. YAP1-fused ependymomas occur almost exclusively in infants and young children—predominantly females under 3 years of age—and exhibit a more indolent course with similar imaging but often larger multi-lobar involvement.
Supratentorial ependymomas account for approximately one-third of intracranial ependymomas and present across a wide age range with two peaks: early childhood and adulthood. The majority of ZFTA-fusion–positive tumors occur in school-age children and adults, whereas YAP1-fusion tumors predominantly affect infants (median age 8.2 months) and young children under three, with a striking female predominance (13 of 15 patients in one series).
References
- Andreiuolo, Felipe, et al. "Childhood supratentorial ependymomas with YAP1‐MAMLD1 fusion: an entity with characteristic clinical, radiological, cytogenetic and histopathological features." Brain Pathology 29.2 (2019): 205-216.
- Perrod, Victoire, et al. "Supra-tentorial ependymomas with ZFTA fusion, YAP1 fusion, and astroblastomas, MN1-altered: characteristic imaging features." Clinical Neuroradiology 34.4 (2024): 939-950.
Supratentorial mass
Intra-axial, extra-ventricular masses—often centered in the frontal or parietal lobes—are characteristic in these cases, with YAP1-fused tumors tending to span three or more lobes more frequently than ZFTA-fused tumors.
The tumor margins are generally well-circumscribed but tend to be lobulated in contour. Ill-defined borders are rare and should prompt consideration of alternative diagnoses such as astroblastoma or high-grade glioma.
On noncontrast CT, the solid components of the tumor typically appear iso- to hyperattenuating, while MRI reveals these regions as iso- to hypointense on T1-weighted sequences and hyperintense on T2-weighted images. Restricted diffusion is noted in nearly 89% of tumors, a reflection of high cellularity and demonstrated by low apparent diffusion coefficient values on diffusion-weighted imaging.
Postcontrast imaging with either CT or gadolinium-enhanced MRI demonstrates robust and heterogeneous enhancement in over 90% of tumors, indicative of rich vascularity and disruption of the blood–brain barrier.
Cystic or necrotic areas are present in approximately 91% of cases, appearing on MRI as nonenhancing regions with fluid-like signal intensity, occasionally showing fluid–fluid levels in the presence of intratumoral hemorrhage.
Calcification is a common finding as well, present in 83% of cases on CT, often in a punctate or coarse distribution, and can serve as a valuable diagnostic clue, particularly in pediatric supratentorial masses.
Peritumoral vasogenic edema is frequently extensive, identified in 86% of cases as hyperintense signal in the adjacent white matter on T2-weighted and FLAIR images.