Interestingly, CD56 expression suggests a malignant phenotype: in fact, under physiological conditions it is limited to T lymphocytes with spontaneous non-MHC-restricted cytotoxicity.27, 49 CD57 was seen in 10% and 5% of PTCL/NOS and AITL respectively. Here, NCAM1 is linked to mature T-cell and NK-cell non-Hodgkin lymphoma.