Figure 4. Abnormal protein accumulation by p53 immunohistochemistry.

Archival tissue blocks containing histologic evidence of anaplasia were available for three of the seven DAWTs determined to be TP53-wt by the absence of TP53 mutation and copy number loss in a single randomly selected frozen tumor sample (the remaining four cases did not have archival tissue within the biopathology center containing clear histologic evidence of anaplasia). (Original magnification 40X for all.)

A) PAJMLZ: The block containing anaplasia shows diffuse abnormal p53 protein accumulation.

B) PALEZT: The block contains anaplastic cells that were stromal that surrounded non-anaplastic blastemal cells. Immunohistochemistry shows nodules of blastemal cells that were largely negative for p53 protein, with anaplastic stromal cells containing marked accumulation of p53 protein.

C) PAJNRH: The block had a microscopic focus of anaplasia, which shows intense abnormal nuclear p53 staining.