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

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 gamma 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.