Concomitant Occurrence of Blastic Plasmacytoid Dendritic Cell Neoplasm and Acute Myeloid Leukaemia after Lenalidomide Treatment for del(5q) Myelodysplastic Syndrome

Background: Myelodysplastic syndromes with chromosome 5 long arm deletion (5q-MDS) may benefit from lenalidomide treatment. However, unresponsive patients have a high risk for clonal evolution and progression to acute myeloid leukemia. Case: We describe a 5q-patient treated with lenalidomide, who concomitantly developed acute myeloid leukemia and blastic plasmacytoid dendritic cell neoplasm, a rare and highly aggressive lymphoma. Conclusions: Evolution of 5q-syndrome to acute myeloid leukemia and blastic plasmacytoid dendritic cell neoplasm may have occurred through various mechanisms, including persistence of neoplastic lenalidomide-resistant stem cells and selection of a more aggressive clone via lenalidomide augmentation of the ARPC1B gene, or because of lenalidomide stimulation on dendritic cells. Further studies are needed to clarify lenalidomide oncogenic potential.