CNS tumor

Ependymal tumors

Tanycytic ependymoma

Topic Completed: 1 August 2012

Minor changes: 25 September 2020

Copyright: 2002-2021,, Inc.

PubMed Search: Tanycytic ependymoma [title]

Eman Abdelzaher, M.D., Ph.D.
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Cite this page: Abdelzaher E. Tanycytic ependymoma. website. Accessed November 27th, 2021.
Definition / general
  • Grade II of IV
  • Within brain or spinal cord (often cervical, Acta Neuropathol (Berl) 2001;101:43) parenchyma
  • Tanyctes are common progenitor cells of both ependymal cells and astrocytes; are elongated, unipolar or bipolar, extend from ventricular lumen to surface of nervous system
  • Important to distinguish from diffuse astrocytomas, which usually cannot be totally excised
Case reports
  • Gross total excision and radiologic surveillance for recurrence
Microscopic (histologic) description
  • Fibrillar variant of ependymoma
  • Discrete margin with surrounding tissue
  • Features of ependymoma and astrocytoma
  • Elongated spindle cells with round / oval nuclei with distinctly light and dark regions of chromatin (similar to ependymoma) and marked fibrillarity (similar to astrocytoma)
  • Ependymal rosettes are typically absent and pseudorosettes only vaguely delineated
Microscopic (histologic) images

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


EMA showing dot-like and ring-like positivity

EMA showing dot-like and ring-like positivity

Cytology description
  • Cells with long, bipolar glial processes and oval nuclei
  • May be no pseudorosettes
  • Resembles pilocytic astrocytoma or schwannoma (Diagn Cytopathol 2001;24:289)
Positive stains
Electron microscopy description
  • Recommended if diagnosis is in doubt; characteristic ependymal features including intracytoplasmic intermediate filaments, prominent intercellular junctions, numerous slender surface microvilli, microvilli lined lumina (Ultrastruct Pathol 1997;21:135)
Differential diagnosis
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