Combination of morphology, flow cytometry and PCR assay to detect bone marrow infiltration in B-cell non-Hodgkin's lymphomas

Morphology on bone marrow biopsy (BMB) samples has historically been the primary method used to detect bone marrow (BM) infiltration in B-cell non-Hodgkin's lymphoma (NHL), while fl ow cytometry (FC) and PCR assays have been generally used as ancillary methods. In this study we evaluated a combined approach utilizing all three methods to detect BM infiltration in patients with NHL both at diagnosis and after therapy.We analyzed 193 patients with NHL, who received simultaneous BMB, FC and PCR assays. Morphology on histologic specimens was used to assess infiltration pattern and immunohistochemistry, FC to analyze immunophenotype, PCR to identify IgH rearrangement, BCL-1/JH and BCL-2/JH translocation.Morphology, FC and PCR assays agreed in 142 cases (73.5%) with more concordance at initial diagnosis than during postchemotherapy follow-up. PCR was the single best-performing test, while combination of morphology and PCR yielded a higher sensitivity than individual methods and was similar to PCR + FC. We observed little added benefit using a third approach.Given the initial importance of histological information evident by morphology, our data suggest that combination of morphology and PCR should be considered the gold standard for evaluation of BM infiltration at diagnosis, while combination of PCR + FC should be employed during post-treatment follow-up.