Introduction
Transplant-associated thrombotic microangiopathy (TA-TMA) is an under-recognized yet potentially devastating complication of hematopoietic stem cell transplantation (HSCT) characterized by endothelial damage, intravascular activation and platelet sequestration, accumulation of microthrombi occluding microcirculation, and red blood cells fragmentation causing non-immune microangiopathic hemolytic anemia (1). Clinical and laboratory features include the triad of hypertension, thrombocytopenia and elevation of lactate dehydrogenase (LDH); as well as schistocytosis in peripheral blood smear, thrombocytopenia, decreased haptoglobin level, and target organ damage such as renal impairment. It had increasingly been identified in recent years (2-5) in both autologous and allogeneic HSCT settings. Reported incidences of TA-TMA vary widely from 0.5% to 76% due to different diagnostic criteria, demographic characteristics, conditioning regimen, donor source, and co-morbidities (6-22). TA-TMA carries a high mortality of 30% to 90% (7, 12, 17, 20, 21, 23), depending on its severity and presence of co-morbidities. This report summarized the experience of TA-TMA in the Hong Kong Children’s Hospital (HKCH), the only territory-wide paediatric transplant centre in Hong Kong since its establishment in 2019, highlighting challenges in management of TA-TMA in this locality.