View source for Diffuse astrocytoma, MYB- or MYBL-altered

{{ Infobox diagnosis
| Name       = {{PAGENAME}}
| Image      = Commons 20220404 000.jpg
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| Caption    = Diffuse astrocytoma, MYB- or MYBL-altered [[H&E stain]].
| Synonyms   =
| Micro      =
| Subtypes   =
| LMDDx      = [[Angiocentric glioma]]
| Stains     = 
| IHC        = GFAP +ve
| EM         =
| Molecular  =
| IF         =
| Gross      = soft, unencapsulated
| Grossing   =
| Site       = brain - usu. temporal
| Assdx      =
| Syndromes  =
| Clinicalhx =
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| Symptoms   =
| Prevalence = common - esp. in children
| Bloodwork  =
| Rads       =
| Endoscopy  =
| Prognosis  = good (WHO Grade I)
| Other      =
| ClinDDx    =
| Tx         =
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'''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. <ref>{{cite journal |vauthors=Bale TA, Rosenblum MK |title=The 2021 WHO Classification of Tumors of the Central Nervous System: An update on pediatric low-grade gliomas and glioneuronal tumors |journal=Brain Pathol |volume= |issue= |pages=e13060 |date=February 2022 |pmid=35218102 |doi=10.1111/bpa.13060 |url=}}</ref>
* 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=== 
<gallery>
File:Commons 20220404 000.jpg|H&E
</gallery>


==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).<ref>{{cite journal |vauthors=Qaddoumi I, Orisme W, Wen J, Santiago T, Gupta K, Dalton JD, Tang B, Haupfear K, Punchihewa C, Easton J, Mulder H, Boggs K, Shao Y, Rusch M, Becksfort J, Gupta P, Wang S, Lee RP, Brat D, Peter Collins V, Dahiya S, George D, Konomos W, Kurian KM, McFadden K, Serafini LN, Nickols H, Perry A, Shurtleff S, Gajjar A, Boop FA, Klimo PD, Mardis ER, Wilson RK, Baker SJ, Zhang J, Wu G, Downing JR, Tatevossian RG, Ellison DW |title=Genetic alterations in uncommon low-grade neuroepithelial tumors: BRAF, FGFR1, and MYB mutations occur at high frequency and align with morphology |journal=Acta Neuropathol |volume=131 |issue=6 |pages=833–45 |date=June 2016 |pmid=26810070 |pmc=4866893 |doi=10.1007/s00401-016-1539-z |url=}}</ref>
* IDH1/2 wildtype.
* H3F3A wildtype.

==Prognosis==
* Excellent (most cases are stable after surgery).

==See also==
*[[Neuropathology tumours]].
*[[Astrocytoma]].

==References==
{{Reflist|2}}

[[Category:Diagnosis]]
[[Category:Neuropathology tumours]]