Coexistence of acute promyelocytic leukemia and Dubin–Johnson syndrome (DJS) has not been previously reported in the literature. The patient was diagnosed with DJS while being investigated for a very high bilirubin level, and the same novel mutation was also detected in her sibling.

A 49-year-old woman was diagnosed with acute promyelocytic leukemia (APL) following examinations performed upon detection of pancytopenia. Thereafter, DJS with a new mutation was diagnosed in the patient who developed differentiation syndrome during follow-up and hyperbilurubinemia after intensive antibiotic and chemotherapy. DSJ normally has a good prognosis and does not require special treatment, but our patient’s jaundice had increased to toxic levels after starting therapy.

We examined the development of unexplained direct hyperbilirubinemia without any increase in liver function tests after chemotherapy and all-trans retinoic acid (ATRA) treatment, along with intensive antibiotic therapy in a patient with newly diagnosed APL. Genetic analysis revealed a homozygous genomic variant NM_000392.5 (ABCC2): c.890dupA (p.Lys298GlufsTer36). According to the American College of Medical Genetics and Genomics (ACMG) criteria, this new variant was categorized as pathogenic. This genomic variant was considered responsible for the current clinical situation and the patient was diagnosed with DSJ. Since the association of APL and DJS has not been previously presented in the literature, we present our case in order to point out that rare diagnoses should be considered in isolated direct hyperbilirubinemia patients who receive intensive treatment. A new mutation was also detected when diagnosing DJS.