Sézary syndrome and mycosis fungoides: An overview, including the role of immunophenotyping

This review discusses the definition and major categories of cutaneous T‐cell lymphoma, Sézary syndrome and mycosis fungoides, and the role of immunophenotyping in their diagnosis. The following key points are raised: (a) Sézary syndrome and mycosis fungoides cells most often have a characteristic CD3+ CD4+ CD7− and/or CD26− immunophenotype. (b) This immunophenotype is not specific, but can assist in the distinction from non‐neoplastic T cells and other subtypes of mature T‐cell neoplasm. (c) However, small subsets of normal and reactive T‐cells can have an overlapping immunophenotype, and can be distinguished by evaluating for additional changes in antigen expression.