Abnormal T-cells and NK cells, continued. All abnormal populations are colored purple. A. This assay can also detect T-lymphoblastic leukemia/lymphoma (T-ALL) but is not designed for deep immunophenotyping of T-ALL. T-ALL shows absence of surface CD3 and bright CD7 expression. The expression of CD10 on CD45 dim T-cells should prompt a thorough assessment for T-ALL. In contrast to AITL, T-ALL does not express CD279/PD-1. B. NK cell lymphomas can also be detected by this assay. This case of an extranodal NK/T-cell lymphoma shows CD2 expression in the absence of surface CD3 and CD5 expression. CD7 is mostly negative, which is an aberrant finding in NK-cells. The NK-cells express neither CD4 nor CD8 and are brightly positive for CD56. Additional testing in this case showed expression of CD94, CD335, and cytoplasmic cytotoxic markers TIA1 and Granzyme B (not shown).