Chronic Lymphocytic Leukaemia
A clonal accumulation of mature but functionally incompetent B lymphocytes that pile up slowly in blood, marrow and nodes rather than dividing rapidly, so most patients are asymptomatic for years and the disease is found incidentally on a routine blood count.
Definition
Chronic lymphocytic leukaemia is a clonal mature B-cell neoplasm involving blood, marrow, lymph nodes and spleen. The cells are functionally abnormal, so lymphocytosis can coexist with impaired immunity.
First principles
CLL is an accumulation disease, not a proliferation disease, and that shapes everything about it
Unlike acute leukaemia, the malignant cells in CLL are mature-appearing small B lymphocytes that fail to undergo apoptosis rather than cells dividing rapidly. They simply accumulate over months to years in the blood, marrow, lymph nodes and spleen, which is why onset is insidious and why many patients are diagnosed incidentally on a full blood count taken for an unrelated reason, rather than through acute illness.
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