Rare occurrence of CD30+ circulating cells in patients with cutaneous CD30+ anaplastic large cell lymphoma: a study of nine patients

Summary Background The presence of a significant percentage of circulating atypical lymphocytes in peripheral blood has already been demonstrated in systemic CD30+ anaplastic large cell lymphoma (ALCL), which implies that a leukaemic component may be present in this subset of lymphomas. However, no similar data are available for the cutaneous counterpart of this particular lymphoproliferation. Objectives To assess the presence of atypical cells, CD30+ lymphocytes and of a dominant T‐cell clone in peripheral blood in a series of patients with cutaneous CD30+ ALCL. Materials and methods Nine patients with either primary (four) or secondary (five) cutaneous CD4+ CD30+ ALCL were selected. The percentage of CD30+ CD4+ lymphocytes among peripheral blood mononuclear cells (PBMC) was determined by flow cytometry and the presence of a dominant circulating T‐cell clone was assessed by polymerase chain reaction targeting the T‐cell receptor γ chain. A control group composed of apparently healthy individuals was similarly studied at the same time. Results The mean percentage of CD30+ cells in PBMC was slightly higher in patients than in controls (3·9% vs. 2·7%) but the difference was not statistically significant. Only two patients displayed more than 5% CD30+ cells, both of whom had a minor tumour burden. A dominant circulating T‐cell clone was detected in only three cases, including these two latter patients. Conclusions The occurrence of a significant percentage of CD30+ CD4+ circulating cells is rare in active cutaneous CD30+ ALCL, either primary or secondary. This percentage is not related to the apparent skin tumour burden but a significant figure appeared to be correlated with the detection of a dominant T‐cell clone in peripheral blood. Overall, these data show that, unlike mycosis fungoides, peripheral blood involvement seems infrequent in cutaneous CD30+ ALCL. The hypothesis that a high percentage of CD30+ circulating cells might be related to the presence of a cryptic systemic disease cannot be ruled out.