Fludarabine, as well as 2-chlorodeoxyadenosine, can induce eosinophilia during treatment of lymphoid malignancies.

We treated 25 patients suffering from low-grade lymphoid malignancies with nucleoside analogues. In 11 patients undergoing treatment with fludarabine, two patients with follicular lymphoma developed a marked absolute peripheral blood eosinophilia devoid of clinical symptoms which resolved without medical intervention. Of 15 patients treated with 2-chlorodeoxyadenosine, one patient with B-cell chronic lymphocytic leukaemia (CLL) experienced repeated episodes of eosinophilia that required steroid treatment. Eosinophilia in these three patients was not coupled to tumour lysis, and we found no correlation between the occurrence of eosinophilia and clinical response to treatment. Thus, for the first time, we can report eosinophilia as a side-effect of fludarabine treatment, and these are also the first published cases of this complication occurring in patients treated with nucleoside analogues for follicular lymphoma and CLL.