Anaplastic pilocytic astrocytoma

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Anaplastic pilocytic astrocytoma
Diagnosis in short

Anaplastic pilocytic astrocytoma. H&E stain.
LM DDx astrocytoma, oligodendroglioma, glioblastoma
Stains PAS-D +ve (eosinophilic granular bodies)
IHC GFAP +ve
Gross usually cerebellar
Site brain - usu. cerebellum
Prevalence very rare - esp. in children
Prognosis poor (analog to WHO Grade III)

Anaplastic pilocytic astrocytoma, abbreviated APA, is a rare high-grade astrocytoma. It can develop from a pilocytic astrocytoma.

General

  • High-grade astrocytoma - behaviour corresponds to WHO Grade III.
  • Some authors prefer the designation pilocytic astrocytoma with anaplastic features.
  • Less than 2% of all pilocytic astrocytomas.[1]
  • De novo cases in the setting of neurofibromatosis 1 reported.
  • Many tumors have history of previous radiation.

Microscopic

Features:[2]

  • At least 4 mitoses/10 high power fields - see HPFitis.
  • Hypercellularity.
  • Necrosis +/-.
  • Pilocytic like (biphasic) - most common.
    1. Eosinophilic granular bodies +/-.
  • Small cell (32%)
  • Epithelioid cells (15%)
  • Fibrillary areas resembling diffuse astrocytoma.

DDx of APA (brief):


Images

  • APA, FFPE specimen, HE (WC).

  • Vacular proliferations and necrosis in APA mimicking GBM (WC).

IHC

Features:[3]

  • GFAP +ve (fibres).
  • p53: +ve.
  • KI-67: high 25%.
  • ATRX loss may be present.[4]
  • IDH1 (R132H) -ve.
  • H3F3A (K27M) -ve.

Molecular

  • Molecular data is still limited.
  • KIAA1549-BRAF fusion transcripts and NF1 cases reported[5]


Prognosis

  • Poor, but better than conventional glioblastoma.[6]
  • Prognostic unfavourable paramters include: Necrosis, Mitoses and previous radiation.

See also

References

  1. ↑ Rodriguez, FJ.; Scheithauer, BW.; Burger, PC.; Jenkins, S.; Giannini, C. (Feb 2010). "Anaplasia in pilocytic astrocytoma predicts aggressive behavior.". Am J Surg Pathol 34 (2): 147-60. doi:10.1097/PAS.0b013e3181c75238. PMID 20061938.
  2. ↑ Rodriguez, FJ.; Scheithauer, BW.; Burger, PC.; Jenkins, S.; Giannini, C. (Feb 2010). "Anaplasia in pilocytic astrocytoma predicts aggressive behavior.". Am J Surg Pathol 34 (2): 147-60. doi:10.1097/PAS.0b013e3181c75238. PMID 20061938.
  3. ↑ Rodriguez, FJ.; Scheithauer, BW.; Burger, PC.; Jenkins, S.; Giannini, C. (Feb 2010). "Anaplasia in pilocytic astrocytoma predicts aggressive behavior.". Am J Surg Pathol 34 (2): 147-60. doi:10.1097/PAS.0b013e3181c75238. PMID 20061938.
  4. ↑ Ebrahimi, A.; Skardelly, M.; Bonzheim, I.; Ott, I.; Mühleisen, H.; Eckert, F.; Tabatabai, G.; Schittenhelm, J. (Jun 2016). "ATRX immunostaining predicts IDH and H3F3A status in gliomas.". Acta Neuropathol Commun 4 (1): 60. doi:10.1186/s40478-016-0331-6. PMID 27311324.
  5. ↑ Jones, DT.; Hutter, B.; Jäger, N.; Korshunov, A.; Kool, M.; Warnatz, HJ.; Zichner, T.; Lambert, SR. et al. (Aug 2013). "Recurrent somatic alterations of FGFR1 and NTRK2 in pilocytic astrocytoma.". Nat Genet 45 (8): 927-32. doi:10.1038/ng.2682. PMID 23817572.
  6. ↑ Rodriguez, FJ.; Scheithauer, BW.; Burger, PC.; Jenkins, S.; Giannini, C. (Feb 2010). "Anaplasia in pilocytic astrocytoma predicts aggressive behavior.". Am J Surg Pathol 34 (2): 147-60. doi:10.1097/PAS.0b013e3181c75238. PMID 20061938.
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