CNS & pituitary tumors

Gliomas, glioneuronal tumors and neuronal tumors

Ependymal tumors

Subependymoma


Editorial Board Member: P.J. Cimino, M.D., Ph.D.
Deputy Editor-in-Chief: Chunyu Cai, M.D., Ph.D.
Eman Abdelzaher, M.D., Ph.D.

Last author update: 6 March 2024
Last staff update: 6 March 2024

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PubMed Search: Subependymoma

Eman Abdelzaher, M.D., Ph.D.
Page views in 2024 to date: 4,156
Cite this page: Abdelzaher E. Subependymoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/cnstumorsubependymoma.html. Accessed July 13th, 2024.
Definition / general
  • Glioma characterized by the clustering of uniform to mildly pleomorphic tumor cell nuclei in an abundant fibrillary matrix prone to microcystic change
  • CNS WHO grade 1
Essential features
  • Slow growing tumors that tend to occur within the ventricles of middle aged and elderly adults (Brain Pathol 2008;18:469)
  • Histologically characterized by clustered nuclei in an abundant fibrillary background
  • Benign biological behavior with excellent prognosis (J Neurosurg 2021;136:736)
Terminology
ICD coding
  • ICD-O: 9383/1 - subependymoma
  • ICD-11: 2A00.0Y & XH8FZ9 - other specified gliomas of brain & subependymoma
Epidemiology
Sites
Pathophysiology
  • Embryological origin of these tumors remains uncertain; possible precursors include subependymal glia, astrocytes of the subependymal plate, ependymal cells and a mixture of astrocytes and ependymal cells (Brain Pathol 2008;18:469, J Neurosurg 2021;136:736, Arch Pathol Lab Med 1999;123:306)
  • Specific mechanisms by which the documented chromosomal or genetic abnormalities contribute to tumorigenesis are currently unknown
Etiology
Clinical features
Diagnosis
  • Neuroimaging: MRI and CT (AJR Am J Roentgenol 1995;165:1245)
  • Biopsy
  • WHO essential diagnostic criteria
    • Circumscribed glioma with clustering of tumor cell nuclei within expansive, focally microcystic fibrillary matrix
    • Lack of conspicuous nuclear atypia
    • Absent or minimal mitotic activity
    • For unresolved lesions: DNA methylation profile aligned with subependymoma
Radiology description
Radiology images

Contributed by Eman Abdelzaher, M.D., Ph.D.
MRI, T2

MRI, T2

MRI, FLAIR

MRI, FLAIR



Images hosted on other servers:
Lateral ventricle

Lateral ventricle

Spinal cord subependymoma, MRI

Spinal cord subependymoma, MRI

Intraparenchymal subependymoma, MRI

Intraparenchymal subependymoma, MRI

Fourth ventricle subependymoma

Fourth ventricle subependymoma

Prognostic factors
Case reports
Treatment
Clinical images

Images hosted on other servers:
Smooth contoured lobulated mass

Smooth contoured lobulated mass

Spinal cord subependymoma

Spinal cord
subependymoma

Intraparenchymal subependymoma

Intraparenchymal
subependymoma

Gross description
Gross images

Contributed by Eman Abdelzaher, M.D., Ph.D.
Circumscribed, lobulated mass

Circumscribed, lobulated mass

Frozen section description
  • Lobular pattern
  • Clusters of monomorphic nuclei with absent or mild pleomorphism; nuclei appear hyperchromatic and pointy with no prominent nucleoli or mitotic figures (Indian J Neurosurg 2019;8:64, OUHSC: Case 501-2 [Accessed 29 January 2024])
  • Dense, fine, fibrillary background
  • Microcystic formations impart a spongy appearance on low magnification; some bluish mucoid material is identified in some microcysts
Frozen section images

Images hosted on other servers:
Monomorphic nuclei in fibrillary pattern

Monomorphic nuclei in fibrillary pattern

Spongy appearance

Spongy appearance,
clustering of nuclei,
hyperchromatic /
pointy nuclei

Microscopic (histologic) description
Microscopic (histologic) images

Contributed by Eman Abdelzaher, M.D., Ph.D., David Taylor, M.D. and Nazila Azordegan, M.D.
Nuclear clustering and microcystic change Nuclear clustering and microcystic change

Nuclear clustering and microcystic change

Nuclear clustering Nuclear clustering

Nuclear clustering

Nuclear clustering

Nuclear clustering

Nuclear clustering

Nuclear clustering


Microcystic change Microcystic change

Microcystic change

Microcystic change and nuclear pleomorphism

Microcystic change and nuclear pleomorphism

Uniform nuclei

Uniform nuclei

Uniform nuclei Uniform nuclei

Uniform nuclei


Lobulated tumor

Lobulated tumor

Clustered nuclei in fibrillary background Clustered nuclei in fibrillary background

Clustered nuclei in fibrillary background

Dot-like perinuclear EMA Dot-like perinuclear EMA

Dot-like perinuclear EMA

GFAP

GFAP

Virtual slides

Images hosted on other servers:
Subependymoma

Subependymoma

Cytology description
Cytology images

Images hosted on other servers:
Cohesive tissue clumps

Cohesive tissue
clumps, elongated
cytoplasmic
processes

Positive stains
Electron microscopy description
Electron microscopy images

Images hosted on other servers:
Ultrastructural findings in subependymoma

Ultrastructural findings in subependymoma

Molecular / cytogenetics description
  • Distinct DNA methylation profiles of subependymomas at different anatomical locations (supratentorial, posterior fossa and spinal) are documented
  • Chromosomal copy number variations are infrequent in subependymomas at different anatomical locations
    • Recurrent copy number abnormalities are loss of chromosome 19 (most frequently within posterior fossa subependymomas [79%] and less frequent within supratentorial [50%] and spinal [40%] subependymomas) and partial chromosome 6 loss in spinal and posterior fossa subependymomas (Neuro Oncol 2018;20:1616, Cancer Cell 2015;27:728, Brain Pathol 2008;18:469)
  • TRPS1 and PTPN1 gene mutations have been documented (J Neurosurg 2021;136:736)
  • Posterior fossa subependymomas express KIT at high levels (Cancer Cell 2015;27:728)
  • Brainstem subependymomas can have H3 K27M mutations but this does not carry the rapidly lethal prognosis of diffuse midline gliomas (Hum Pathol 2019;84:262)
  • Do not appear to be associated with NF2 mutations that are found in other ependymal neoplasms (J Neurooncol 2007;85:297)
Molecular / cytogenetics images

Images hosted on other servers:
Key molecular and clinical characteristics

Key molecular and clinical characteristics

Methylation profiling

Methylation profiling

Copy number variations

Copy number variations

Videos

Subependymoma

Sample pathology report
  • Lateral ventricular mass lesion, gross total resection:
    • Subependymoma, CNS WHO grade 1
    • Molecular genetics: DNA methylation profile aligned with subependymoma
Differential diagnosis
Board review style question #1

66 year old man presented with a headache. MRI of brain showed a nonenhancing mass lesion projecting into the right lateral ventricle. The mass was surgically excised. The image above shows the characteristic morphology of this lesion. What is the typical microscopic finding seen in this entity?

  1. High mitotic activity
  2. Nuclear clustering
  3. Palisading necrosis
  4. True ependymal rosettes
Board review style answer #1
B. Nuclear clustering. Nuclear clustering is a typical microscopic finding of subependymomas. Answer A is incorrect because mitoses are absent or rare in typical subependymomas. Answer C is incorrect because palisading necrosis is not a feature of subependymomas. Answer D is incorrect because true ependymal rosettes are not seen in pure subependymomas.

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Reference: Subependymoma
Board review style question #2
The recently described loss of chromosome 19 in subependymomas is most frequent at which anatomical location?

  1. Intraparenchymal subependymoma
  2. Posterior fossa subependymomas
  3. Spinal subependymomas
  4. Supratentorial subependymomas
Board review style answer #2
B. Posterior fossa subependymomas. Loss of chromosome 19 is most frequently encountered within posterior fossa subependymomas (79%). Answers C and D are incorrect because loss of chromosome 19 is less frequent within supratentorial (50%) and spinal (40%) subependymomas. Answer A is incorrect because intraparencymal subependymomas are rare and chromosome 19 loss has not been documented in the studied cases (Int J Surg Pathol 2023;31:69).

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Reference: Subependymoma
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