Splenic rupture secondary to pegfilgrastim in a healthy allogeneic peripheral blood hematopoietic stem cell donor.

Granulocyte-colony stimulating factor (G-CSF) is widely used to mobilize peripheral blood stem cells (PBSCs) for hematopoietic cell transplantation (HCT). G-CSF is generally well-tolerated but can cause life-threatening complications such as splenic rupture in rare cases. Long-acting pegfilgrastim (Peg-G) is increasingly used for PBSC mobilization, but its risk for splenic rupture is less well characterized. Here, we report a case of splenic rupture secondary to Peg-G administered for PBSC mobilization in a healthy 25-year-old male haploidentical donor. He presented with left upper quadrant abdominal pain shortly after PBSC harvest 5 days following administration of Peg-G. Computed tomography (CT) revealed splenomegaly with rupture, and small bloody peri-splenic and pelvic ascites. He was managed conservatively, but the next evening his symptoms temporarily worsened, prompting a repeat CT scan, which showed no change. Thereafter, the pain did not recur, and the patient was discharged on day 8. One month later, a follow-up CT demonstrated complete resolution. To our knowledge, this is the first case of splenic rupture secondary to Peg-G for PBSC mobilization in a healthy allogeneic donor and highlights the importance of vigilance for this rare complication when G-CSF or Peg-G is used for mobilization.