Immunophenotypic shift of CD4 and CD8 antigen expression in primary cutaneous T‐cell lymphomas: a clinicopathologic study of three cases

Primary cutaneous T‐cell lymphomas ( CTCL ) comprise a heterogeneous group of neoplasms with diverse clinical behavior. Mycosis fungoides ( MF ) is the most common type of CTCL . Immunophenotypical shift during progression of the disease is a rare event and its significance is unknown. We present three primary CTCL cases that showed an immunophenotypical shift and poor prognosis. Conventional hematoxylin/eosin and immunohistochemical‐stained sections were examined in all the cases. Molecular analysis for rearrangement of the T‐cell receptor ( TCR ) gene was performed in two cases. One case was classified as MF , while the other two lacked epidermotropism, and were considered primary cutaneous peripheral T‐cell lymphoma ( PTCL ), NOS . Two cases were CD3 +/ CD4 + and one case was CD3 +/ CD8 + at diagnosis. The first two patients suffered many relapses and eventually, new CTCL lesions with a CD3 +/ CD8 + phenotype were observed. Both cases revealed identical clonal TCR rearrangements on the initial and late lesions, supporting the interpretation of a single clonal proliferation with different phenotypes. The third case progressed with skin recurrences and pulmonary lesions with a predominant CD3 +/ CD4 +/ CD8 − phenotype. All cases manifested poor prognosis and two patients died of lymphoma. Immunophenotypical shift between CD4 and CD8 in CTCL seems to be a rare phenomenon that may be associated with disease progression.