Mycosis Fungoides : Immunostains
Immunophenotype of Mycosis Fungoides (MF): The lymphocytes of MF are mature helper/memory T-cells that are CD4+, CD3+, and CD8-ve in the vast majority of cases. The lymphocytes express pan-T-cell antigens CD2, CD3, CD5, but may be negative for CD7. Some view this as "loss" of CD7, whereas others prefer to call MF as neoplastic expansion of normally occurring minority population of CD7-ve helper T-cells. There is a minor CD8+ component which is thought to be the anti-tumor response. Plaque and tumor stage lesions may show decreased expression of CD2, CD3, and CD5. CD25 (IL-2 receptor) is positive in 50% of cases. PD1 is frequently positive. Some plaques and tumors of MF may show CD30+ large anaplastic cells. Rare cases have aberrant expression of CD20.