Pediatric Pulmonary Hypertension Associated With Treatment of Myeloproliferative Disorders and Malignant Tumors.

Pulmonary hypertension (PH) is a severe complication observed in pediatric patients after hematopoietic cell transplantation or chemotherapy. A review of records at Hokkaido University Hospital (2014-2024) identified four cases of PH, each with different etiologies, including pulmonary arterial hypertension, pulmonary veno-occlusive disease, and microthromboembolism. Contributing factors included splenic atrophy, corticosteroid-responsive inflammation, and potential drug-induced vascular remodeling. Although transient PH usually resolves, late-onset PH emphasizes the need for long-term echocardiographic monitoring. These findings underscore the importance of individualized management, avoiding pulmonary vasodilators without proper evaluation, and addressing underlying conditions such as thrombotic microangiopathy or interstitial lung disease.