Atraumatic subdural hematoma following filgrastim mobilization in a peripheral blood stem cell donor

Filgrastim is widely used for hematopoietic stem cell mobilization and is generally safe in healthy donors. Rare cases of vasculitis and subarachnoid hemorrhage have been reported, but subdural hematoma (SDH) has not, to our knowledge, been described as a nontraumatic event in this setting.

A 29-year-old man received filgrastim 10 mcg/kg once daily for 5 days prior to peripheral blood stem cell collection via apheresis. Several hours after apheresis, he developed a sudden headache that progressively worsened and repeatedly woke him from sleep. He presented to the emergency department, where head CT demonstrated an acute left convexity SDH with mass effect. CT angiography and intraoperative inspection showed no aneurysm, arteriovenous malformation, or venous sinus thrombosis. Platelet count and coagulation studies were within normal limits, and there was no history of trauma or anticoagulant use. He subsequently deteriorated clinically, requiring intubation and emergent craniectomy.

This case highlights a rare but serious intracranial hemorrhagic event temporally associated with filgrastim administration in a healthy stem cell donor. The absence of alternative etiologies warrants reporting this temporal association.