Apparently monomorphic small mature lymphocytes, with very dense chromatin.
Presence of Gumprecht shadows as sign of cell fragility.
Sometimes presence of atypical lymphocytes (if ALY > 15% => CLL).
The 2008 WHO classification indicates that Chronic Lymphocytic Leukemia (CLL) can be evocated when Monoclonal B Lymphocytosis >5 G/L. Matutes score (obtained by flow cytometry) should be 4-5.