CD45RA+immunophenotype in mycosis fungoides: clinical, histological and immunophenotypical features in 22 patients

Background: Mycosis fungoides (MF) is a cutaneous T-cell lymphoma (CTCL) us ually characterized by a T-helper memory phenotype (CD3+, CD4+, CD8-, CD45R 0+). Aberrant phenotypes are more commonly seen in the tumor stages. CD45RA expression has so far been documented in only a few cases of CD8+ or TCR g amma delta+ CTCL and in some pagetoid reticulosis cases. Methods: Two hundred and fifteen MF patients were immunophenotyped in our l aboratory between January 1992 and June 2000 and 22 cases of CD45RA+ MF (8. 7%) were identified by immunohistochemical analysis. Results: The majority of these CD45RA+ patients (20/22) showed a patch-plaq ue stage disease and an indolent clinical course, as expected in early-stag e ME The remaining 2 patients presented with stage IIB and IVA MF, and were characterized by an aggressive clinical course, with systemic spread. The immunohistochemical analysis revealed that CD45RA+ neoplastic cells belonge d to the memory compartment, displaying a CD62L-, CD11a+, CD29+ phenotype. Most patients showed aberrant phenotypes, with a loss of T-cell lineage mar kers and expression of cytotoxic molecules or gamma-delta chain of the T-ce ll receptor. Conclusions: Our data show that CD45RA+ MF is a rare variant of CTCL and sh ares with the classic MF cases both the clinical features and disease cours e, even if it is characterized by a higher incidence of immunopathological abnormalities.