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| *Commonly abbreviated ''AT/RT''. | | *Commonly abbreviated ''AT/RT''. |
| *May be written ''atypical teratoid rhabdoid tumour'', i.e. without the forward slash, or ''atypical teratoid-rhabdoid tumour'' (AT-RT). | | *May be written ''atypical teratoid rhabdoid tumour'', i.e. without the forward slash, or ''atypical teratoid-rhabdoid tumour'' (AT-RT). |
| | | {{Main|Atypical teratoid/rhabdoid tumour}} |
| ===General===
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| *Usually supratentorial, occasionally in posterior fossa, case reports of spinal cord.
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| ===Microscopic===
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| Features:
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| *Cellular.
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| *Small round cells usu. with a prominent nucleolus.
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| *Rhabdoid cells.
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| **Cells with eosinophilic granular cytoplasm + eccentric nucleus.
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| *Mitoses.
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| *+/-[[Necrosis]] (common).
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| DDx:
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| *[[Primitive neuroectodermal tumour]] (PNET).
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| *[[Medulloblastoma]].
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| *[[Diffuse astrocytoma]].
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| *[[Choroid plexus carcinoma]].
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| *[[Embryonal carcinoma]].
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| Images:
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| *[http://commons.wikimedia.org/wiki/File:Rhabdoidtumourcell.jpg Rhabdoid tumour cell (WC)].
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| *[http://commons.wikimedia.org/wiki/File:ATRT-HE-Overview.jpg AT/RT (WC)].
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| *[http://commons.wikimedia.org/wiki/File:ATRT-INI1.jpg AT/RT -ve for INI1 (WC)].
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| *[http://path.upmc.edu/cases/case99/micro.html AR/RT (upmc.edu)].
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| ===IHC===
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| *BAF-47 -ve ([[AKA]] ''INI1'', [[AKA]] ''SMARCB1'' - the HGNC symbol<ref name=omim601607>{{OMIM|601607}}</ref>) - virtually diagnostic.
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| **Endothelial cells +ve control.
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| *S-100 +ve.
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| **Few other brain tumours express it.
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| *Vimentin +ve (perinuclear condensation).
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| Others:
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| *GFAP +ve (focal - in tumour cells).
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| *EMA +ve (patchy cytoplasmic).
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| *Smooth muscle actin +ve.
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| ==Oligodendroglioma== | | ==Oligodendroglioma== |