CD8A and aggressive NK-cell leukemia: In particular, the differential diagnosis with aggressive NK cell leukemia was based on surface sCD3 and CD8 positivity, CD56 negativity, and evidence of TCRα rearrangement in systemic EBV+ T cell LPDs, and also sCD3/CD8 negativity, CD56 positivity and germline TCRα patterns in aggressive NK cell leukemia cases.