**5. Issues of the combination of CML and chronic lymphocytic leukemia (CLL) in the clonal association**

CML and CLL are different hematological malignancies characterized by their cause of disease, their origin of hematopoietic lineages, laboratory findings and clinical presentations, and different immune phenotypes. CML and CLL require different treatment strategies. In general, there are no many problems or issues in the diagnosis and differential diagnosis on both of CML and CLL.

Recently, there were some rare cases reported in the combination of CML and CLL, which raises a question as to whether the myeloid and lymphoid malignant clones derived from the common malignant stem cells or CML and CLL are two independent simultaneous events.

A group performed a study on three-way translocations by flow cytometric sorting using monoclonal antibody anti-CD19 lacked the BCR-ABL rearrangement. Their results suggested CML and CLL were from two different clones B-cell transformation occurred in a Ph-B-cell subset [57].

Wu et al. reported a novel CML case with three-way translocations involved in chromosomes 9, 22, and 11 cytogenetically and confirmed by fluorescence in-situ

*Milestone Histories and Paradigmatic Genetic Discoveries of Chronic Myeloid Leukemia (CML) DOI: http://dx.doi.org/10.5772/intechopen.90938*

hybridization (FISH). It was found the deletion of chromosome short arm (4p) confirmed by comparative genome hybridization microarray. This patient had more than 10 years indolent chronic lymphoblastic leukemia (CLL) history without progression over several years, and cytogenetic test was normal. Interestingly, both CML and CLL got remission after treatment for CML indicating the possibility of the relevant if clonal revolution [58]. These results might indicate the association of Ph chromosome in the leukemogenesis of CML and CLL.

Armarego et al. reported five CML cases in the combination of CLL history and one case with the deletion of short arm of chromosome 17(17p). All patients were treated for both CLL and CML, and a satisfactory outcome was achieved from the five cases studied separately [59].

The association of CML and CLL raises the issues that the combination of CML and CLL is the two different events or a result from a clonal evolution either from CML or CLL that needs to be classified further.
