en Pediatric Hematology & Oncology Pediatric Hematology & Oncology گزارش مورد Case report <div style="text-align: justify;"><span style="line-height:2;"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><strong>Background: </strong>Acute promyelocytic leukemia (APL) is characterized by a life-threatening coagulopathy, traditionally associated with hemorrhagic complications. However, thrombotic events, including arterial infarction, are increasingly recognized as significant contributors to morbidity during induction therapy.<br> <strong>Case Presentation:</strong> We report a 16-year-old male diagnosed with APL who developed extensive splenic infarction two weeks after initiation of all-trans retinoic acid (ATRA). He presented with persistent fever and left upper quadrant pain. Abdominal imaging revealed a large subcapsular splenic infarct without evidence of macrovascular thrombosis. Despite improving blood counts and resolution of initial cytopenias, systemic inflammation and coagulopathy persisted. ATRA was temporarily discontinued due to suspicion of differentiation syndrome, which may have delayed disease control. With resumption of ATRA and addition of arsenic trioxide (ATO), along with supportive care, the patient achieved complete hematologic remission with undetectable minimal residual disease (MRD) at day 50.<br> <strong>Conclusion:</strong> Thrombotic complications such as splenic infarction can occur in APL even during early treatment, emphasizing the dynamic and dual nature of hemostatic dysregulation. Clinicians should maintain a high index of suspicion for non-infectious causes of fever and abdominal pain in APL patients. Early recognition and uninterrupted targeted therapy are critical to resolving the underlying prothrombotic state and improving outcomes.</span></span></span></div> Acute promyelocytic leukemia, Coagulopathy, Thrombosis , Splenic infarction, Disseminated intravascular coagulation, All-trans retinoic acid 10 13 http://ijbc.ir/browse.php?a_code=A-10-1239-3&slc_lang=en&sid=1 pourya mashategan 100319475328460012845 100319475328460012845 No Department of Pediatrics, School of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran. hassan Abolghasemi HassanAbol@Yahoo.com 100319475328460012846 100319475328460012846 Yes Department of Pediatrics, School of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.