INTERLEUKIN-2-INDUCED SPLENIC ENLARGEMENT

Background. Splenomegaly in patients with cancer raises the suspicion of tumor involvement. Splenic enlargement in the absence of splenic me tastases, however, has been reported in patients treated with interleu kin-2 (IL-2) immunotherapy. This study characterizes the change in spl een size that occurred in 42 patients treated with IL-2 between 1989 a nd 1993 for nonhematologic malignancies.Methods. Computed tomography ( CT) scans before and during immunotherapy were available for review on all 42 patients and after immunotherapy on 16 of these patients. The splenic index was measured for each CT by a single reader blinded to t he time course of IL-2 therapy. Results. Mean splenic index increased 64.1% from 646 cm(3) (standard deviation [SD], 387) pre-IL-2 to 1059 c m(3) (SD, 534) during therapy with IL-2 (P < 0.0001). The splenic inde x remained elevated at 1112 cm(3) (SD, 633) after completion of IL-2 t herapy. Conclusions. Splenomegaly, temporally associated with IL-2 the rapy for nonhematologic malignancies, is likely to represent a sequela of therapy and not tumor progression.