A Rare Case of Concurrent Chronic Lymphocytic Leukemia and Therapy-Unrelated Acute Myeloid Leukemia That Evolved From Myelodysplastic Neoplasm

It is unusual for patients to have two or more concurrent hematologic malignancies. Simultaneous chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) are even more rare, and most reported cases are therapy-related. The incidence of cases of concurrent CLL and therapy-unrelated AML is even more rare at <1%. In this case report, we present a very rare case of a patient with concurrent CLL and therapy-unrelated myelodysplastic neoplasm (MDS) that transformed to AML. Peripheral flow cytometry and a bone marrow biopsy showed separate populations of myeloblasts and monoclonal B-lymphocytes. Both populations of cells were subjected to fluorescence in situ hybridization (FISH) testing and next-generation sequencing (NGS) which revealed an abnormal clone with the deletion of the long arm of chromosome seven (7q-) and RUNX1 and NF1 among myeloid cells, suggestive of adverse risk MDS-related AML. These cytogenetic findings were not observed among the lymphoid cells tested. The pathogenesis of concurrent CLL and de novo AML is unknown and requires further investigation. Given the differing cytogenetics among each cell population, the CLL and AML may have developed as separate clonal processes. With a further understanding of the pathogenic mechanism, this may influence the treatment decision-making process.