Subependymoma

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Sujit Routray, M.D. [2]

Synonyms and keywords: Subependymomas

Overview

Subependymoma is a type of the brain tumor; specifically, it is a rare form of ependymal tumor.[1] Subependymoma is a benign (WHO grade I) tumor, which is slow growing and non-invasive.[2]

Pathophysiology

Gross Pathology

  • Subependymoma is most commonly seen in the fourth ventricle, but can arise anywhere where there is ependyma. The distribution in the ventricular system is as follows:[3]
  • On gross pathology, subependymoma is characterized by a small, well circumscribed mass attached to the ventricular wall by a narrow pedicle.

Microscopic Pathology

  • On microscopic histopathological analysis, subpendymoma is characterized by microcystic spaces and bland appearing cells without appreciable nuclear atypia or mitoses. The nuclei tend to form clusters.

Immunohistochemistry

  • Subependymoma is demonstrated by positivity to tumor marker such as GFAP.[4]

Differentiating Protoplasmic Astrocytoma from other Diseases

Epidemiology and Demographics

Age

  • Subependymoma is a rare disease that tends to affect middle-aged adults and the elderly population (typically 5th to 6th decades).[6]

Gender

  • Males are more commonly affected with subependymoma than females. The male to female ratio is approximately 2.3 to 1.[6]

Natural History, Complications and Prognosis

Natural History

Complications

  • Common complication of subependymoma include:[7]

History and Symptoms

History

  • When evaluating a patient for subependymoma, you should take a detailed history of the presenting symptom (onset, duration, and progression), other associated symptoms, and a thorough family and past medical history review.

Symptoms

  • Typically patients of subependymoma are asymptomatic and small lesions are discovered incidentally.
  • Symptoms of subependymoma include:[8]

CT

  • Head CT scan is helpful in the diagnosis of protoplasmic astrocytoma. On CT scan, protoplasmic astrocytoma is characterized by:[9]
  • Hypodense mass
  • Positive mass effect
  • No enhancement
  • Cystic or fluid attenuation, due to the aforementioned prominent mucinous microcystic component

MRI

  • Brain MRI is helpful in the diagnosis of subependymnoma. On MRI, subependymoma is characterized by:
MRI component Findings

T1

  • Iso - hypointense compared to white matter
  • Homogeneous but may be heterogeneous in larger lesions

T2

  • Hyperintense compared to adjacent white and grey matter
  • Heterogeneity may be seen in larger lesions, with susceptibility related signal drop out due to calcifications
  • No adjacent parenchymal edema (as no brain invasion is present)

Fluid-attenuated inversion recovery (FLAIR)

  • Large areas of T2 hyperintensity suppress on FLAIR
  • These are not macrocystic, but rather represent the areas with abundant microcystic change)

T1 with contrast

  • Little or no enhancement

Other Imaging Findings

Magnetic Resonance Spectroscopy

Magnetic Resonance Perfusion

  • MR perfusion may be helpful in the diagnosis of protoplasmic astrocytoma, which demonstrates no elevation of relative cerebral blood volume (rCBV).[9]

Electroencephalogram

  • Electroencephalogram (EEG) is performed in cases of protoplasmic astrocytoma to record the continuous electrical activity of the brain and locate the seizure activity.[10]

Biopsy

  • Biopsy of the protoplasmic astrocytoma tumor, taken through a needle during a simple surgical procedure, helps to confirm the diagnosis.[11]

Treatment

  • The treatment of protoplasmic astrocytoma depends on the clinical presentation, tumor size, and location.[11]
  • Surgery: The predominant therapy for protoplasmic astrocytoma is surgical resection.[11]
  • Radiotherapy: Radiotherapy may be used in protoplasmic astrocytoma post-operatively or at the time of recurrence or progression.[12]
  • Chemotherapy: Chemotherapy may have a role in recurrent and de-differentiated tumors.[12]


 
 
 
 
 
 
 
 
 
 
 
 
Treatment of protoplasmic astrocytoma
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Surgery
 
 
 
Radiotherapy
 
 
 
Chemotherapy
 
 
 
 
 
 
 
 
 
 
 
 
 

References

  1. Subependymoma. Wikipedia 2016. https://en.wikipedia.org/wiki/Subependymoma. Accessed on January 12, 2016
  2. Subependymoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/subependymoma. Accessed on January 12, 2016
  3. Radiographic features of subependymoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/subependymoma. Accessed on January 12, 2016
  4. Pathology of subependymoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/subependymoma. Accessed on January 12, 2016
  5. Intraventricular neoplasms and lesions. Dr Henry Knipe and Dr Vinod G Maller et al. Radiopaedia 2016. http://radiopaedia.org/articles/intraventricular-neoplasms-and-lesions. Accessed on January 12, 2016
  6. 6.0 6.1 Epidemiology of subependymoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/subependymoma. Accessed on January 12, 2016
  7. 7.0 7.1 Clinical presentation of subependymoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/subependymoma. Accessed on January 12, 2016
  8. KE, Changshu. "Subependymoma: a case report and the review of literatures". doi:10.3969/j.issn.1672-6731.2011.01.021.
  9. 9.0 9.1 9.2 Radiological features of protoplasmic astrocytoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/protoplasmic-astrocytoma. Accessed on January 8, 2016
  10. Radiographic features of fibrillary astrocytoma. Dr Henry Knipe and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/fibrillary-astrocytoma. Accessed on January 4, 2016
  11. 11.0 11.1 11.2 Treatment and prognosis of protoplasmic astrocytoma. Dr Bruno Di Muzio and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/protoplasmic-astrocytoma. Accessed on January 8, 2016
  12. 12.0 12.1 Treatment and prognosis of low grade infiltrative astrocytoma. Dr Ahmed Abd Rabou and A.Prof Frank Gaillard et al. Radiopaedia 2016. http://radiopaedia.org/articles/low-grade-infiltrative-astrocytoma. Accessed on January 8, 2016

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