Transplant-associated thrombotic microangiopathy (TA-TMA) is an under-recognized yet potentially devastating complication of hematopoietic stem cell transplantation which had increased awareness in recent years. This report summarizes territory-wide experience of paediatric TA-TMA in the Hong Kong Children’s Hospital from 1 April 2019 to 31 March 2021. Total six patients were identified among 73 transplants performed. Median duration of onset was 2.5 months post-HSCT. Three patients died while all 3 survivors suffered from stage 2 to 5 chronic kidney disease despite administration of eculizumab. To conclude, recognition and diagnosis of TA-TMA is challenging. Clinical utility of complement blockage with eculizumab is limited.

Severe hypercholesterolemia mediated by graft-versus-host disease of liver in patients underwent allogeneic hematopoietic stem cell transplantation is a recognized yet overlooked phenomenon. Reports in literature is limited in both adult and pediatric population and none had been reported in Chinese children to date. As lipoprotein X hypercholesterolemia is due to regurgitation of cholesterol and bile salts into systemic circulation rather than overproduction by hepatocytes, usage of statins to downregulate cholesterol synthesis is not effective. Here we report 2 local cases to increase awareness of transplant physicians and endocrinologists of this association and avoid unnecessary and ineffective usage of statins.

A 4-year old female with acute myeloid leukemia complicated with right calcaneal osteomyelitis due to Mycobacterium abscessus with subcutaneous abscesses extending to popliteal and groin regions after 2 courses of induction chemotherapy according to NOPHO-AML 2012 protocol. She required multiple operations and prolonged anti-mycobacterial therapy. High index of suspicion for mycobacterial infection is required for immunocompromised patients with prolonged fever or unusual presentation. Mycobacterial osteomyelitis is rare, difficult to diagnose and treat, and may necessitate prolonged interruption of anti-leukemic therapy. Multidisciplinary collaboration in patient management is crucial. Long term toxicity of antimicrobials with uncertain efficacy should not be overlooked.