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.