Determination of immunophenotypic aberrancies provides better assessment of peripheral blood involvement by mycosis fungoides/Sézary syndrome than quantification of CD26- or CD7- CD4+ T-cells.

The MF/SS cell quantification method using immunophenotypic aberrancies, as recommended by the ICCS, allows to distinguish MF/SS cells from background benign T-cells and enables for more accurate staging, especially among patients currently being considered to have B0 and B1 stage diseases.