Pleomorphic xanthoastrocytoma

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Pleomorphic xanthoastrocytoma, abbreviated PXA, is neuropathology tumour classically associated with seizures in children.

Pleomorphic xanthoastrocytoma
Diagnosis in short

Pleomorphic xanthoastrocytoma.
LM marked nuclear atypia, eosinophilic granular bodies - very common, inflammation (chronic), no necrosis
Site brain - typical temporal lobe
Clinical history seizure, children & young adults

General

Features:

  • Rare (less than 1% of all astrocytic tumors).
  • Classically in the temporal lobe in children and young adults.
  • Associated with seizures.
  • Moderately aggressive (WHO Grade II).[1]
  • Anaplastic PXA (grade III) - rare. [2]
  • ICD-O: 9424/3.

Gross

  • Temporal lobe - classic.
  • Usually assoc. with the leptomeninges,[1] i.e. superficial (in up 96%).

  • Typical appearance is one of a superficially situated tumor, here a mural nodule, associated with an underlying cyst (AFIP)

  • Hemorrhagic pleomorphic xanthoastrocytoma (PXA), MRI (WC/RadsWiki)

Microscopic

Features:[3]

  • Fibrillary background.
  • Large cells with marked nuclear atypia.
  • Multinuclear cells possible.
  • Reticulin meshwork.
  • Lipidized cells.
  • Eosinophilic granular bodies - very common.[1]
  • Inflammatory cells (lymophocytic perivascular cuffs).


Grading

  • Grade II: Mitotic activity is low, no necrosis.
  • Grade III anaplastic PXA: more than 5/10 HPF, may have necrosis.

Notes: Anaplastic PXA was introduced in the WHO2016 revision as a distinct entity. In the past, the tumor was called PXA with anaplastic features.

DDx:

Images

  • HE smear of a PXA. (WC/AFIP)

  • HE intraoperative frozen section of PXA. (WC/jensflorian)

  • The tumor is aptly named due to ist pleomorphic cells. HE, high magnification. (WC/marvin101)

  • The pleomorphic cells must not be confused with a higly anaplastic glioma. HE, intermed magnification.(WC/jensflorian)

  • Focal xanthomatous cells as in the name PXA. HE, intermed magnification.(WC/jensflorian)

  • Perivascular lymphocytic cuffs are not uncommon. HE, intermed-low magnification.(WC/jensflorian)

  • Eosinophilc granular bodies in a PXA. HE, intermed magnification.(WC/jensflorian)

  • A delicate meshwork of retiulin fibers in PXA. Gomori, intermed magnification.(WC/jensflorian)

  • GFAP IHC is often heterogenous in PXA. Intermed magnification.(WC/jensflorian)

www:

Stains

Image:

IHC

  • GFAP +ve.
  • S-100 +ve.
  • CD68 +ve.
  • CD34 frequently.
  • MAP2+ve and Synapto+ve pleomorphic cells
  • MIB-1 usually low.

Molecular

  • BRAF V600E mutation in 2/3 of the cases[5]
    • (mostly in temporal, reticulin-fiber rich tumors)[6]

See also

References

  1. ↑ 1.0 1.1 1.2 Fouladi, M.; Jenkins, J.; Burger, P.; Langston, J.; Merchant, T.; Heideman, R.; Thompson, S.; Sanford, A. et al. (Jul 2001). "Pleomorphic xanthoastrocytoma: favorable outcome after complete surgical resection.". Neuro Oncol 3 (3): 184-92. PMID 11465399.
  2. ↑ Louis, DN.; Perry, A.; Reifenberger, G.; von Deimling, A.; Figarella-Branger, D.; Cavenee, WK.; Ohgaki, H.; Wiestler, OD. et al. (Jun 2016). "The 2016 World Health Organization Classification of Tumors of the Central Nervous System: a summary.". Acta Neuropathol 131 (6): 803-20. doi:10.1007/s00401-016-1545-1. PMID 27157931.
  3. ↑ Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson; Aster, Jon (2009). Robbins and Cotran pathologic basis of disease (8th ed.). Elsevier Saunders. pp. 1333. ISBN 978-1416031215.
  4. ↑ 4.0 4.1 Dias-Santagata, D.; Lam, Q.; Vernovsky, K.; Vena, N.; Lennerz, JK.; Borger, DR.; Batchelor, TT.; Ligon, KL. et al. (2011). "BRAF V600E mutations are common in pleomorphic xanthoastrocytoma: diagnostic and therapeutic implications.". PLoS One 6 (3): e17948. doi:10.1371/journal.pone.0017948. PMID 21479234.
  5. ↑ Schindler, G.; Capper, D.; Meyer, J.; Janzarik, W.; Omran, H.; Herold-Mende, C.; Schmieder, K.; Wesseling, P. et al. (Mar 2011). "Analysis of BRAF V600E mutation in 1,320 nervous system tumors reveals high mutation frequencies in pleomorphic xanthoastrocytoma, ganglioglioma and extra-cerebellar pilocytic astrocytoma.". Acta Neuropathol 121 (3): 397-405. doi:10.1007/s00401-011-0802-6. PMID 21274720.
  6. ↑ Koelsche, C.; Sahm, F.; Wöhrer, A.; Jeibmann, A.; Schittenhelm, J.; Kohlhof, P.; Preusser, M.; Romeike, B. et al. (Apr 2014). "BRAF-mutated pleomorphic xanthoastrocytoma is associated with temporal location, reticulin fiber deposition and CD34 expression.". Brain Pathol 24 (3): 221-9. doi:10.1111/bpa.12111. PMID 24345274.
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