Bone marrow assessment in B-cell chronic lymphocytic leukaemia: aspirate or biopsy? A comparative study in 258 patients

To evaluate the relative merits and prognostic value of bone marrow aspirate and bone marrow biopsy in the assessment of bone marrow infiltration in B-cell chronic lymphocytic leukaemia (CLL), two observers independently reviewed the percentage of lymphocytes in bone marrow aspirate (lymphocytic infiltration, LI) and the bone marrow histological pattern (BMP) in 258 patients. The inter-observer reproducibility and agreement was higher for BMP than for LI. BMP was an independent prognostic factor for survival in the whole series, whereas LI only had independent predictive value in stage A patients. In the entire series, disease progression was predicted by either BMP and LI, whereas in stage A patients only by BMP. Regarding low-risk CLL (smouldering CLL or A'1 substage), BMP led to a more reproducible identification of these clinical forms than LI. In conclusion, although both BMP and LI are of value to estimate bone marrow infiltration in CLL and to predict the outcome of the disease, BMP is more reliable and reproducible than LI.