Chronic lymphocytic leukaemia: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up.

The diagnosis of CLL requires the presence of ‡5000 B lymphocytes/ll in the peripheral blood for the duration of at least 3 months. The clonality of the circulating B lymphocytes needs to be confirmed by flow cytometry. The leukaemia cells found in the blood smear are characteristically small, mature lymphocytes with a narrow border of cytoplasm and a dense nucleus lacking discernable nucleoli and having partially aggregated chromatin.