Chronic myeloid leukaemia and hairy cell leukaemia coexisting in a single patient: difficulties at diagnosis and rational of the therapeutic strategy

Chronic myeloid leukemia (CML) and hairy cell leukemia (HCL) are two distinct haematological disorders. Only one single case of coexistence of the two pathologies at diagnoses has been previously reported. We present a second case of coexistence at diagnosis, indicating the diagnostic procedures involving morphological, immunophenotyping, and molecular testing. We decided to use Interferon as common first-line therapy and Imatinib and Rituximab (anti-CD20 monoclonal antibody), to improve the first-line therapy result, obtaining a complete molecular remission for CML and clinical remission with molecular minimal residual disease for HCL. After a critical analysis of the results, we speculate on the different clonal origin of the two pathologies.