From viral encounter to leukemic challenge: a case of isolated molecular relapse in a child with acute promyelocytic leukemia after SARS-CoV-2 infection

 Acute promyelocytic leukemia (APL) is a type of aggressive acute myeloid leukemia (AML), characterized by the presence of abnormal promyelocytes in the bone marrow and bloodstream. The abnormal promyelocytes found in APL can lead to severe complications such as bleeding and blood clot formation.

 A 7-year-old boy diagnosed with APL encountered a unique occurrence of isolated molecular relapse following a recent episode of SARS-CoV-2 infection while undergoing routine monitoring for treatment response. The relapse was confirmed by the detection of the PML/RARalpha gene abnormality in both the peripheral blood and bone marrow samples. Notably, during relapse, the boy displayed symptoms indicative of a cerebral ischemic stroke; however, effective management was achieved through the administration of low molecular weight heparin (LMWH) and corticosteroids. Subsequently, the patient underwent an allogenic bone marrow transplantation. Of note, throughout an 18-month period of close monitoring, no complications were reported.

 The detection of the PML-RARA transcript in peripheral blood can serve as a valuable tool for detecting isolated molecular relapse in pediatric APL. In cases where patients are undergoing immunosuppressive chemotherapy, the presence of neurological signs and symptoms may be the sole indicator of APL relapse, and it can be thoroughly investigated through the use of MRI with or without diffusion-weighted imaging (DWI). The administration of LMWH is a safe treatment strategy until D-dimer levels return to normal. It has been observed that COVID-19, as seen with other respiratory viruses, may potentially contribute to the relapse of pediatric APL, highlighting its significance in disease progression.