Chronic Lymphocytic Leukaemia

In a nutshell

CLL is an accumulation, not a proliferation, of mature but functionally incompetent B cells, so the disease is slow and often asymptomatic for years. Functional immune failure and, later, marrow crowding explain the infections and cytopenias that eventually develop.

Classic presentation

An older adult found incidentally to have a raised lymphocyte count on a routine blood test, sometimes with painless lymphadenopathy.

Key points

• 1CLL cells look mature but function poorly, so infections occur despite a high total lymphocyte count.