Acute kidney injury in a patient with endothelial activation syndrome after hematopoietic stem cell transplantation

Endothelial activation syndrome (EAS) is an increasingly recognized complication of hematopoietic stem cell transplantation (HSCT) and includes transplant-associated thrombotic microangiopathy (TA-TMA), sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), capillary leak syndrome, idiopathic pneumonia syndrome, and engraftment syndrome. Kidney involvement is common and may be an early marker of systemic endothelial dysfunction. We report a 53-year-old man with high-risk TP53-mutated B-cell acute lymphoblastic leukemia who underwent matched sibling donor allogeneic HSCT. Nine months after transplant, he developed persistent thrombocytopenia, microangiopathic hemolytic anemia, proteinuria, and declining kidney function, fulfilling criteria for high-risk TA-TMA. He initially improved with narsoplimab and supportive care, but his course was complicated by extramedullary leukemia relapse, inotuzumab exposure, progressive SOS/VOD with portal hypertension and ascites, and severe acute kidney injury superimposed on chronic kidney disease. Serum creatinine rose from 1.57 to 6.04 mg/dL with persistent proteinuria, requiring intermittent hemodialysis followed by continuous renal replacement therapy because of hemodynamic instability. He subsequently developed invasive pulmonary aspergillosis with septic shock and progressive respiratory failure. Despite intensive multidisciplinary care, multiorgan dysfunction progressed, and he was discharged for home palliative care. This case highlights the kidney as a sentinel organ of endothelial injury after HSCT and supports EAS as a unifying framework for TA-TMA, SOS/VOD, and severe kidney injury, characterized by complement-mediated endothelial dysfunction and microvascular thrombosis.