Ependymoma is a WHO Grade II-III neuroglial tumor originating from ependymal cells lining the ventricles and spinal canal. Intracranial ependymomas most commonly arise in the fourth ventricle and constitute a significant proportion of posterior fossa tumors in children. The tumor characteristically demonstrates a 'plastic' growth pattern, extending through the foramina of Luschka and Magendie into the cerebellopontine angle cisterns and around the foramen magnum. Heterogeneous enhancement, calcification, cystic components, and hydrocephalus are hallmark findings. Supratentorial ependymomas are more common in adults and may present as parenchymal masses.
Age Range
2-40
Peak Age
5
Gender
Male predominant
Prevalence
Uncommon
Ependymomas arise from ependymal cells lining the ventricular surfaces and central canal. These cells form a single layer of ciliated columnar epithelium with microvilli, playing a role in CSF production and circulation. Tumor cells form characteristic perivascular pseudorosettes and true ependymal rosettes, representing their histopathological hallmark. The extension of fourth ventricle tumors through the foramina of Luschka and Magendie reflects the tumor's soft tissue consistency and 'plastic' growth pattern — the tumor passively spreads through existing anatomic openings rather than invading surrounding structures. The heterogeneous enhancement pattern on imaging reflects variable vascularity within the tumor and areas of microcystic/macrocystic degeneration. Calcifications are dystrophic in nature, representing mineral deposition in necrotic areas within the chronic, slow-growing tumor tissue, detected as hyperdense foci on CT. The heterogeneous signal on T2-weighted images reflects the mixture of solid tumor tissue (intermediate signal), cystic areas (hyperintense), calcification (hypointense), and hemorrhagic products. Mild diffusion restriction on DWI reflects the tumor's moderate cellularity, providing an important differential clue against medulloblastoma's markedly restricted diffusion.
A mass in the fourth ventricle extending in a 'plastic' manner through the foramina of Luschka into the cerebellopontine angle and/or through the foramen of Magendie toward the foramen magnum — the most characteristic and nearly pathognomonic finding of ependymoma. This growth pattern reflects the tumor's soft consistency and tendency to spread through existing anatomic openings rather than invading surrounding tissue.
Iso- to slightly hyperdense mass in the fourth ventricle; punctate or coarse calcifications are present in 40-80% of cases. The tumor may expand the fourth ventricle causing obstructive hydrocephalus. Cystic or necrotic areas appear as hypodense components.
Report Sentence
A heterogeneously dense mass lesion containing calcifications is noted within the fourth ventricle, with findings of obstructive hydrocephalus.
On T2-weighted images, heterogeneous signal intensity mass in the fourth ventricle; solid components are hyperintense relative to brain parenchyma, cystic areas are markedly hyperintense, while calcification and hemorrhagic foci appear hypointense. The tumor extends through the foramina of Luschka into the cerebellopontine angle demonstrating the characteristic 'plastic' growth pattern. Peritumoral edema is typically minimal.
Report Sentence
A mass lesion with heterogeneous signal intensity on T2-weighted images is present in the fourth ventricle, extending through the foramina of Luschka into the cerebellopontine angle.
On T1-weighted images, an iso- to hypointense mass relative to brain parenchyma in the fourth ventricle. Cystic components show low signal isointense to CSF. Hemorrhagic areas may appear T1 hyperintense in the subacute phase (methemoglobin effect). Calcified areas typically show low signal on T1.
Report Sentence
A mass lesion demonstrating iso- to hypointense signal relative to brain parenchyma on T1-weighted images is observed in the fourth ventricle.
Heterogeneous enhancement pattern on post-gadolinium T1-weighted images; solid components show variable enhancement while cystic and necrotic areas do not enhance. The enhancement pattern is typically irregular and patchy. Components extending through the foramina may also enhance, and contrast-enhanced sequences are critical for assessing the true extent of the tumor.
Report Sentence
Following contrast administration, a heterogeneous enhancement pattern is observed in the fourth ventricle mass, with variable enhancement in solid components and absence of enhancement in cystic areas.
On DWI, ependymoma shows mild to moderate diffusion restriction; ADC values are higher than medulloblastoma (typically >0.9 × 10⁻³ mm²/s). This finding is critically important in differentiating from medulloblastoma. Cystic components do not show diffusion restriction. Hemorrhagic or calcified areas may produce susceptibility artifacts.
Report Sentence
The mass demonstrates mild to moderate diffusion restriction on DWI with ADC values higher than those expected for medulloblastoma.
On FLAIR sequences, solid components of the fourth ventricle mass appear hyperintense relative to brain parenchyma. CSF suppression allows better delineation of tumor margins and periventricular ependymal spread. Cystic components may not be completely suppressed (incomplete CSF suppression due to proteinaceous content). Peritumoral edema is detected as hyperintense FLAIR signal but is typically minimal in ependymomas.
Report Sentence
On FLAIR sequence, solid components of the fourth ventricle mass demonstrate hyperintense signal, with CSF suppression allowing clear delineation of tumor margins.
On SWI (Susceptibility Weighted Imaging), calcification and hemorrhagic products demonstrate prominent hypointense 'blooming' artifacts. Calcifications are detected as punctate or coarse foci, and CT correlation aids in differential diagnosis. Intra-tumoral micro- or macro-hemorrhagic foci are also detected more sensitively with SWI compared to conventional sequences.
Report Sentence
Prominent hypointense blooming foci consistent with calcification and/or hemorrhagic products are observed within the tumor on SWI.
MR Spectroscopy demonstrates elevated choline (Cho) peak (increased cellular membrane turnover), elevated myoinositol (mI) peak (glial marker), and reduced N-acetylaspartate (NAA) peak (neuronal damage/loss). Cho/NAA and Cho/Cr ratios are elevated. Elevated myoinositol is characteristic of glial-origin tumors and may be prominent in ependymoma. Lactate peak may be detected in necrotic areas.
Report Sentence
MR Spectroscopy demonstrates elevated choline peak, reduced NAA peak, and elevated myoinositol peak, findings supportive of a glial-origin neoplastic process.
Criteria
Well-differentiated, slow-growing glial tumor located in the fourth ventricle. Most common type in children.
Distinct Features
Foraminal extension with 'plastic' growth, heterogeneous enhancement, calcification (40-80%), cystic components, mild restriction on DWI. Distinguished from medulloblastoma by lower cellularity and less prominent diffusion restriction.
Criteria
Parenchymal mass in the cerebral hemispheres; may be associated with the lateral ventricle or entirely extraventricular. More common in adults.
Distinct Features
Presents as a large cystic-solid mass. Prominent cystic component and peritumoral edema are more than posterior fossa location. Hemorrhage is more frequent. RELA fusion gene positivity is frequent in this subtype and is a poor prognostic marker.
Criteria
High-grade ependymoma showing high mitotic activity, vascular proliferation, and necrosis. More aggressive course and worse prognosis.
Distinct Features
More prominent heterogeneous enhancement, more necrosis, more prominent diffusion restriction on DWI compared to Grade II, increased rCBV on perfusion. Higher risk of leptomeningeal dissemination.
Criteria
Slow-growing WHO Grade II tumor occurring almost exclusively in the spinal canal (conus medullaris/cauda equina). Intracranial location is extremely rare.
Distinct Features
Well-defined, homogeneously enhancing mass in the spinal canal. May be hyperintense on T1 due to mucoid content. Hemorrhage is common and hemosiderin rim may be seen (cap sign). Calcification is rare.
Distinguishing Feature
Medulloblastoma arises from the roof (vermis) and shows marked diffusion restriction (ADC <0.7), while ependymoma typically has a floor origin and milder restriction (ADC >0.9). Calcification is less common in medulloblastoma and foraminal extension is not expected.
Distinguishing Feature
Pilocytic astrocytoma shows a cyst with mural nodule pattern, while in ependymoma solid component predominates with intratumoral cystic areas. Calcification is rare in pilocytic astrocytoma and foraminal extension is absent.
Distinguishing Feature
Choroid plexus papilloma demonstrates marked homogeneous enhancement and 'cauliflower-like' lobulated morphology, while ependymoma shows heterogeneous enhancement. Choroid plexus papilloma seen in lateral ventricle in children, fourth ventricle in adults.
Distinguishing Feature
Intraventricular metastases are extremely rare, typically parenchymal with known primary malignancy. Ependymoma shows single lesion with foraminal extension.
Distinguishing Feature
Hemangioblastoma shows cystic mass with intensely enhancing mural nodule and flow voids. VHL association is important clue. Different from heterogeneous enhancement of ependymoma.
Urgency
urgentManagement
surgicalBiopsy
Not NeededFollow-up
Postoperatif MR 24-72 saat içinde rezidü değerlendirmesi için, ardından düzenli MR takibi (ilk yıl 3 aylık, sonra 6 aylık). Spinal MR leptomeningeal yayılım değerlendirmesi için. Anaplastik tipte adjuvan radyoterapi.The primary approach in ependymoma treatment is maximal safe surgical resection; gross total resection is the most important prognostic factor. Early postoperative MRI (24-72 hours) is mandatory for residual tumor assessment. Adjuvant focal radiotherapy is administered in anaplastic ependymoma and subtotal resection. Chemotherapy role is limited. CSF cytology and spinal MRI should screen for leptomeningeal dissemination. Five-year survival is 70-80% for Grade II and 40-60% for Grade III.
Maximal safe surgical resection is the primary approach for ependymoma treatment. Total resection is the most important prognostic factor. Adjuvant radiotherapy is applied after subtotal resection. The role of chemotherapy is limited. Spinal MRI staging is required due to CSF pathway spinal dissemination (5-15%).