Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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December 19, 2024
Enhancing Subependymoma
- Background:
- Subependymomas are rare, benign (WHO Grade 1), slow growing, noninvasive intraventricular neoplasms.
- Sporadic tumor with a slight male predominance and most common in the middle-aged adult (fifth to sixth decades).
- Clinical Presentation:
- Usually asymptomatic
- Symptoms, when present, are related to increased intracranial pressure, hydrocephalus, and mass effect. Sensory or motor symptoms may arise if lesion occurs in the spine
- Key Diagnostic Features:
- CT: Iso- hypodense to white matter, rarely cysts or hemorrhage may be seen.
- MRI
- T1: isointense, sometimes hypointense
- T1 postcontrast: variable enhancement—usually none/mild. We present a case of a pathology-confirmed subependymoma that demonstrates enhancement. This is less commonly seen.
- T2: hyperintense; larger lesions may demonstrate internal signal heterogeneity due to cystic changes, hemorrhage, or calcifications.
- FLAIR: hyperintense
- Differential Diagnosis:
- Ependymoma: Enhancing heterogeneous circumscribed lesion that may contain blood products. Ependymomas are typically seen in a younger population (35–45 years old) compared with subependymomas. Ependymomas are usually more pliable “tooth-paste like” lesions that squeeze out of the foramina.
- Choroid plexus papilloma: Lobulated well-defined masses iso-hyperdense to brain parenchyma on CT, often with associated hydrocephalus. Homogeneous marked contrast enhancement demonstrates a “frond-like” pattern.
- Central neurocytoma: Typically, a “bubbly” enhancing lesion with calcifications seen in the lateral ventricles, adherent to the septum pellucidum and occurring largely in the pediatric population. MR spectroscopy may show a stronger choline peak compared with subependymoma.
- Hemangioblastoma: Vascular intra-axial tumor that occurs in the posterior fossa and spinal cord but is not usually intraventricular. Hemangioblastoma typically consists of an enhancing mural nodule and cyst.
- Treatment:
- If the patient is asymptomatic, observation and close serial imaging follow-up is usually sufficient.
- Surgical resection is often curative and has a good prognosis. Resection is indicated if the patient is symptomatic or if there is radiographic evidence of enlargement.
- Total resection is more possible in the lateral ventricles. Large debulking can usually be achieved for fourth ventricular subependymomas often with good clinical response.
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