CLL is a chronic, usually indolent neoplasm of mature lymphocytes, found in older adults. The overall incidence is 3 per 100,000, but in adults 65-69 years old, the incidence is about 12 per 100,000.
The lymphocyte count is elevated, usually ranging from 10K to 150K/uL. CLL should be suspected when the lymphocyte count persistently remains above 5000/uL (normally lymphocytes are less than 4000/uL).
The lymphoid cells in CLL are slightly larger than the normal lymphocyte. They share the features of nuclear condensation and sparse cytoplasm.
Flow cytometry shows expression of CD 19, 20, 5, and 23. Surface immunoglobulin is a weakly expressed IgM or IgD, and light chain restriction is present.
Most patients follow an indolent course, with survival from 5 to more than 10 years. Most will not need treatment at the time of diagnosis. Eventually lymphocyte counts will rise and displace normal marrow cells, resulting in cytopenias. Some patients follow an aggressive course - rapidly rising lymphocyte counts, or transformation to more atypical lymphocytes that are resistant to therapy.
Hypogammaglobulinemia occurs in CLL resulting in infectious complications. Also, autoimmune disorders are common, particularly autoimmune hemolytic anemia, thrombocytopenia, and neutropenia. These consequences can be life threatening.
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