Supplementary Material for: An acute promyelocytic leukemia resistant to all-trans retinoic acid: a case report of the ZBTB16::RARa variant and review of the literature

Introduction Acute promyelocytic leukemia (APL) is characterized by the PML::RARa gene fusion and treatment consists of all-trans retinoic acid (ATRA). Rarely, genetic APL variants have been described which are insensitive to ATRA treatment and are therefore associated with a worse prognosis. Rapid identification of the APL variant is essential to start the correct treatment. Case presentation Here we present a case of a 66-year old male patient with weight loss and arthralgia. Laboratory results showed an anemia and mild leukocytosis with predominantly monocytes. Bone marrow investigation unexpectedly revealed a t(11;17)(q23;q21). This raised suspicion of an ATRA resistant APL. By demonstrating the ZBTB16::RARa gene fusion, the diagnosis was confirmed. Conclusion This case study emphasizes the importance of integrated diagnostics and provides guidance to recognize the ZBTB16::RARa APL, which is the most prevalent ATRA resistant APL. Furthermore, an overview of other genetic APL variants is presented and how to treat these uncommon diseases in clinical practice.