Occult bone marrow involvement in patients with diffuse large B‐cell lymphoma: results of a pilot study

Aims: It is known that advanced stage disease in diffuse large B‐cell lymphoma (DLBCL) confers a poor prognosis, and staging investigations are routinely performed at diagnosis, including a bone marrow (BM) biopsy. However, examination of the BM is usually limited to routine light microscopy, with the role of ancillary investigations remaining unestablished. The aim of this pilot study was to estimate the incidence of occult marrow involvement using flow cytometry, immunohistochemistry and immunoglobulin heavy chain (IgH) gene rearrangements, and to determine the impact on survival.Methods: Clinical and pathological data were obtained on 36 patients diagnosed with DLBCL. Immunohistochemistry using CD3, CD45RO, CD20 and CD79a, and polymerase chain reaction (PCR) to look for IgH gene rearrangements were performed on formalin fixed BM trephines.Results: Nine patients had morphologically apparent BM involvement. Occult marrow involvement was found in seven of 36 (19.4%) patients using the additional diagnosti...