Background: Long-term oral dasatinib administration can induce pulmonary arterial hypertension (PAH) in pediatric patients with Philadelphia chromosome-positive (Ph +) acute lymphoblastic leukemia (ALL). We describe the findings in two pediatric cases involving Ph + ALL patients who developed cardiovascular events such as PAH after dasatinib treatment, and present a review of the related literature. Case presentation: Two pediatric patients diagnosed with B-cell ALL ( BCR-ABL P190 fusion gene positive) received conventional chemotherapy and imatinib simultaneously, which was then changed to dasatinib because of a partial response. The two patients developed PAH after 18 months and 6 years of dasatinib therapy. All signs and symptoms improved after immediate discontinuation of dasatinib and symptomatic treatment. Conclusions: Pediatric Ph + ALL patients receiving dasatinib should be carefully monitored for serious cardiopulmonary and vascular events such as PAH. Development of adverse reactions should be followed by immediate and permanent discontinuation of oral dasatinib. Dynamic monitoring by echocardiography is recommended when administering dasatinib for maintenance therapy.

Transplantation-associated thrombotic microangiopathy (TA-TMA) is one of the most serious complications of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and is characterized by microvascular hemolytic anemia and thrombocytopenia. To further our understanding of the clinical characteristics of TA-TMA in pediatric patients, we retrospectively analyzed 20 pediatric patients with TA-TMA from August 1, 2016 to December 31, 2021 in our center. During this period, 209 patients received allo-HSCT in our department, 20 (9.6%) of whom developed TA-TMA. TA-TMA was diagnosed at a median of 94 (7–289) days post-HSCT. Eleven (55%) patients had early TA-TMA within 100 days post-HSCT, while the other 9 (45%) patients had TA-TMA thereafter. The most common symptom of TA-TMA was ecchymosis (55%), while the main signs were refractory hypertension (90%) and multi-cavity effusion (35%). Five (25%) patients had central nervous system symptoms (convulsions and lethargy). Median follow-up time was 8 (1–26) months. All 20 patients had progressive thrombocytopenia, with 16 patients receiving transfusion of platelets that was ineffective. Ruptured red blood cells were visible in only two patients with peripheral blood smears. Cyclosporine A or Tacrolimus (CNI) dose was reduced once TA-TMA was diagnosed. Nineteen cases were treated with low-molecular-weight heparin, 17 patients received plasma exchange, and 12 patients were treated with rituximab. TA-TMA-related mortality percentage in this study was 45% (9/20). Of the 11 patients who were effectively treated initially, 4 died of sepsis and acute respiratory failure. In conclusion, platelet decline and/or ineffective transfusion post-HSCT should be considered an early indicator of TA-TMA in pediatric patients. TA-TMA in pediatric patients may occur without evidence of peripheral blood schistocytes. Aggressive treatment is required once diagnosis is confirmed, but the long-term prognosis is poor.