Acute Promyelocytic Leukemia With Long and Short Isoforms of PML::RARA Fusion Transcripts Complicated by Abdominal Distension and Acute Edematous Pancreatitis During Induction Treatment: A Case Report.

The introduction of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has transformed the outcome of acute promyelocytic leukemia (APL) from a uniformly fatal disease to one of the most curable human malignancies in recent decades. However, early mortality caused by coagulopathy, infection, multi-organ failure, and differentiation syndrome (DS) during disease onset and induction treatment remains a major issue in APL, especially in elderly patients who may suffer from higher treatment-related mortality due to a higher vulnerability to treatment toxicities. Herein, we present a case of an elderly patient with APL with rare mixed long (L-) and short (S-) isoforms of PML::RARA fusion transcripts who had multiple complications at disease onset. In addition, the initiation of treatment with ATRA in combination with ATO led to the rapid onset of severe DS. In particular, this patient experienced a rare clinical feature of DS, acute edematous pancreatitis (AEP). Furthermore, due to the patient's refractory abdominal distension related to the dose of ATRA, ATO, and Realgar-Indigo Naturalis Formula (RIF), we have to repeatedly adjust the doses of these drugs that the patient can maximally tolerate. Nevertheless, the patient achieved complete remission (CR) even after receiving a substandard dose of these drugs. However, the patient relapsed, acquired the FLT3-ITD mutation nine months later, and experienced abdominal distension again while receiving the standard doses of ATRA and RIF. Therefore, these drugs were adjusted to the maximum tolerated dose based on the experience with the initial induction treatment, and the patient achieved CR after four weeks of reinduction treatment. We report that this case may provide some clinical information for the diagnosis and treatment of similar patients with APL.