Bone Marrow Specific Scatter Pattern on Multiple Myeloma and the M:E Ratio and Cellularity Analysed by the CELL-DYN 4000® Methodology

INTRODUCTION: Optical microscopy is the reference method for the morphological evaluation of bone marrow aspirates; however, in spite of permitting a good qualitative evaluation, the relative quantification of the different type of cells is time consuming and not precise. Regardless the efforts to develop automatic methodologies, no precise and reliable methods are available. CELL-DYN 4000® haematological analyzer uses the MAPSS® technology, based on optical light dispersion, fluorescence and impedance, with great accuracy in differential cellular blood counts.

STUDY PURPOSE:

1. to establish the correlation between the optical microscopy and the automatically CELL-DYN 4000® bone marrow examination concerning the cellularity and the myeloid/erythroid ratio.

2. to study the bone marrow scatter pattern on haematological diseases.

MATERIAL AND METHODS: 84 bone marrow samples (in K₃EDTA) collected for diagnostic purposes among patients attending the Haematology clinic of Centro Hospitalar de Coimbra. Bone marrow films were stained by May-Grünwald-Giemsa’s, analysed by two different Haematologists and the diagnosis were confirmed by flow cytometry studies. Bone marrow automatic analysis were performed by CELL-DYN 4000® using CBC(N), Extended Count(W) and Resistant(R) methodologies.

Statistical analysis: Pearson’s correlation for agreement between automatic methodologies for erythroid lineage and lymphoid series counts; Pearson’s correlation for M:E ratio; Cohen’s Kappa Test for the cellularity; Fisher’s Exact Test to determine whether a specific graphical pattern was associated with a particular haematological disease.

RESULTS: Comparing bone marrow studies by manual and automatic methods we verified:

1. a good correlation (r=0,769, p<0,0001) with R methodology for erythroid lineage and lymphoid series, despite the interference of erythroblasts in the lymphoid series;

2. an excellent agreement (k>0,808) in the cellularity assessment and an excellent correlation (r=0,955; p<0,0001) with the R methodology in M:E ratio.

We also found a very good association (c²=24; p<0,0001) of a specific scatter pattern and Multiple Myeloma (n=10) which is different from Plasmocytic Leukaemia (n=2) and Monoclonal Gammopathy of Undetermined Significance (MGUS) (n=2).

CONCLUSIONS: The present study shows that the bone marrow M:E ratio, as well as the cellularity evaluation by CELL-DYN® 4000 R methodology are reliable. It also shows the association between a specific graphic pattern and Multiple Myeloma. Morphological analysis is the gold standard for bone marrow examination and it will be, probably, never discharged, however, these data confirm the possibilities of having a good global evaluation of bone marrow samples by automatic methods.