Differentiation Between Ependymoma, Schwannoma, and Meningioma
Ependymoma, schwannoma, and meningioma are distinct CNS tumors with characteristic clinical, radiological, and histopathological features that guide their diagnosis and management.
Origin and Location
Ependymoma
- Origin: Neuroectodermal origin, arising from ependymal cells lining the ventricular system 1
- Location: Primarily intraventricular or paraventricular; commonly found in the fourth ventricle in children and spinal cord in adults 1
- Distribution: Account for 1.8% of all primary CNS tumors and 6.8% of all gliomas 1
Schwannoma
- Origin: Arise from Schwann cells of cranial or spinal nerves 2
- Location: Most commonly vestibular schwannomas (VS) from the eighth cranial nerve; represent 6-8% of all intracranial tumors and 80-94% of cerebellopontine angle tumors 2
- Association: Strongly associated with neurofibromatosis type 2 (NF2), particularly bilateral vestibular schwannomas 1
Meningioma
- Origin: Arise from arachnoid cap cells of the meninges 1
- Location: Attached to the dura mater; can occur anywhere along the dural surface 1
- Prevalence: Most common primary CNS tumor from age 35 years through old age; more common in women 1
Clinical Presentation
Ependymoma
- Symptoms depend on location and size
- Intracranial: Increased intracranial pressure, headache, vomiting
- Spinal: Back pain, sensory/motor deficits related to spinal cord compression 1
Schwannoma
- Vestibular schwannomas: Hearing loss (95%), tinnitus (63%), disequilibrium (61%), headache (32%) 2
- Symptoms primarily due to compression of surrounding structures (cranial nerves, vessels, brainstem) 2
Meningioma
- Often asymptomatic and discovered incidentally
- Symptoms depend on location: seizures, focal neurological deficits, headache
- Generally slow-growing 1
Radiological Features
Ependymoma
- Intraventricular or paraventricular location
- Variable enhancement pattern
- May show "drop metastases" in the spinal canal 1
Schwannoma
- Well-circumscribed, enhancing masses in cerebellopontine angle or along nerve roots
- MRI is the gold standard for diagnosis 2
- Often shows cystic components and heterogeneous enhancement 1
Meningioma
- Extra-axial, dural-based masses with homogeneous enhancement
- Often show a "dural tail" sign
- May demonstrate calcification and hyperostosis of adjacent bone 1
Histopathology
Ependymoma
- WHO grades I-III (myxopapillary ependymoma is grade I)
- Characteristic perivascular pseudorosettes and true ependymal rosettes
- Nine molecular subgroups identified across different anatomical compartments 1
- Tanycytic ependymoma variant can be mistaken for schwannoma 3
Schwannoma
- WHO grade I tumors
- Biphasic pattern with Antoni A (compact) and Antoni B (loose) areas
- Verocay bodies (palisading nuclei)
- Strong S-100 protein immunoreactivity 2
Meningioma
- WHO grades I-III, most are grade I
- Whorled pattern of meningothelial cells
- Psammoma bodies (calcified concretions)
- Often show positive staining for epithelial membrane antigen (EMA) 1
Molecular Characteristics
Ependymoma
- Distinct DNA methylation profiles and genetic alterations across nine molecular subgroups 1
- Molecular classification more precise than histology alone in predicting biological behavior 1
Schwannoma
- NF2 gene mutations with loss of schwannomin/Merlin protein 4
- Abnormal interaction between hyaluronan and CD44 receptor contributes to tumorigenesis 5
Meningioma
- NF2 mutations in approximately 60% of sporadic cases 1
- Multiple meningiomas often associated with NF2 1
- More common in women, suggesting hormonal influence 1
Treatment Approaches
Ependymoma
- Primary treatment: Maximal safe surgical resection 1, 6
- Adjuvant therapy: Radiotherapy recommended for anaplastic (grade III) ependymomas and incompletely resected grade II tumors 1, 6
- Spinal ependymomas: Gross total resection is curative in most cases; radiotherapy reserved for incomplete resection 1
Schwannoma
- Management options: Observation ("watch-and-wait"), surgery, or radiotherapy 2
- Surgical approach: Retrosigmoid suboccipital approach commonly used 2
- Goal: Preservation of neurological function, especially facial nerve function and hearing 2
- Recurrence rate: 0.5-5% after microsurgical removal 2
Meningioma
- Management: Surveillance or surgery depending on growth history and symptoms 1
- Surgical indications: Significant growth, parenchymal edema, or clinical symptoms 1
- Radiosurgery: May be helpful for symptomatic growing tumors in difficult locations like cavernous sinus 1
Prognosis
Ependymoma
- 5-year overall survival: 83.4%
- 10-year overall survival: 79.1% 1
- Prognosis depends on tumor location, extent of resection, and molecular subgroup 1
Schwannoma
- Generally benign with excellent long-term survival
- Functional outcomes (hearing, facial nerve function) are key determinants of quality of life 2
Meningioma
- Excellent prognosis for WHO grade I tumors
- Higher grade tumors have higher recurrence rates and worse outcomes 1
Key Distinguishing Features
- Ependymoma: Intraventricular location, perivascular pseudorosettes, association with ventricular system
- Schwannoma: Association with cranial nerves (especially vestibular), S-100 positivity, Antoni A and B areas
- Meningioma: Dural attachment, whorled pattern, psammoma bodies, female predominance