Overproduction of cells is not the main problem in chronic leukemia. The problem is that chronic leukemia cells live much longer than normal white blood cells, resulting in accumulation of too many mature granulocytes or lymphocytes. The second factor to consider in classifying leukemia is the type of bone marrow cells that are affected. If granulocytes or monocytes are involved, the leukemia is classified as myelogenous leukemia. If the cancer develops from bone marrow lymphocytes, it is called lymphocytic leukemia.
Malignant lymphomas are also cancers of lymphocytes.
But, unlike lymphocytic leukemias which develop in the bone marrow, lymphomas develop from lymphocytes in lymph nodes or other organs. In addition to these four main types, there are a few other types and subtypes of chronic leukemia. But, HCL is often considered separately from CLL because of several important differences in symptoms and treatment. The cells of HCL also appear different under the microscope. These two subtypes of CLL tend to have a more aggressive course and are less likely than the usual type to respond to treatment.