NCIt definition : A slowly progressing leukemia characterized by a clonal (malignant) proliferation
of maturing and mature myeloid cells or mature lymphocytes. When the clonal cellular
population is composed of myeloid cells, the process is called chronic myelogenous
leukemia. When the clonal cellular population is composed of lymphocytes, it is classified
as chronic lymphocytic leukemia, hairy cell leukemia, or T-cell large granular lymphocyte
leukemia.;
Alternative definition : NCI-GLOSS: A slowly progressing cancer that starts in blood-forming tissues such as
the bone marrow, and causes large numbers of white blood cells to be produced and
enter the blood stream.;