Spleen enlargement following recombinant human granulocyte colony-stimulating factor administration for peripheral blood stem cell mobilization

BACKGROUND AND OBJECTIVES: Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is widely used to mobilize peripheral blood stem cells (PBSC) for autologous or allogeneic transplants. Such treatment may cause spleen enlargement; exceptionally, spontaneous spleen rupture has been reported. We investigated changes in spleen size during stem cell mobilization. DESIGN AND METHODS: We evaluated spleen size, comparing palpation with ultrasound (US)-evaluated longitudinal diameter and volume, in 13 healthy donors and 22 patients with a hematological malignancy who were undergoing PBSC mobilization with rhG-CSF-including regimens. RESULTS: Intraobserver and interobserver variability of US-calculated spleen volume was very low; the correlation between the volume calculated by US and that measured by 3-dimensional computed tomography was excellent. During mobilization, spleen enlargement was detected by palpation in 17% of subjects, by US-measured longitudinal diameter in 60%, and by US-calculated volume in 91%. The median increase in spleen volume was 300 mL (range, 54-820; p