Diffuse astrocytoma, MYB- or MYBL-altered

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Diffuse astrocytoma, MYB- or MYBL-altered
Diagnosis in short

Diffuse astrocytoma, MYB- or MYBL-altered H&E stain.
LM DDx Angiocentric glioma
IHC GFAP +ve
Gross soft, unencapsulated
Site brain - usu. temporal

Prevalence common - esp. in children
Prognosis good (WHO Grade I)

Diffuse astrocytoma, MYB- or MYBL-altered is a low-grade, often pediatric-onset astrocytoma. It is very rare.

General

  • CNS WHO grade 1.
  • Entity introduced in 2021. [1]
  • Rare epilepsy-associated tumor.
  • Median time to surgery often exceeds more than 10 years.
  • No sex predilection.

Imaging

  • T1 hypointense.
  • Non-enhancing.
  • Occasionally large cysts.

Gross

  • Soft, unencapsulated.
  • Grey to white.

Microscopic

Features:

  • Diffusely growing.
  • Minimal incereased cell density.
  • Monomorphic, bland glial cells.
  • Entrapped neurons.
  • Usu. no mitotic activity

Notes:

  • Focally angiocentric pattern may be present.

DDx

  • Normal white matter
  • Angiocentric glioma


Images


Stains

Features:

  • GFAP +ve.
  • Olig2 -ve.
  • MAP2 -ve.
  • CD34 -ve.
  • ATRX retained.

Molecular

  • Structural variant of MYB or MYBL1 (most common fusion partners: MAML2, MMP16 , PCDGHA1).[2]
  • IDH1/2 wildtype.
  • H3F3A wildtype.

Prognosis

  • Excellent (most cases are stable after surgery).

See also

References

  1. "The 2021 WHO Classification of Tumors of the Central Nervous System: An update on pediatric low-grade gliomas and glioneuronal tumors". Brain Pathol: e13060. February 2022. doi:10.1111/bpa.13060. PMID 35218102.
  2. "Genetic alterations in uncommon low-grade neuroepithelial tumors: BRAF, FGFR1, and MYB mutations occur at high frequency and align with morphology". Acta Neuropathol 131 (6): 833–45. June 2016. doi:10.1007/s00401-016-1539-z. PMC 4866893. PMID 26810070. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4866893/.