The examination of histological and cytological preparations of bone marrow is an important part of the diagnosis and staging of lymphoid malignancy. Although bone marrow aspirates are easy to obtain and can demonstrate the presence of abnormal lymphoid cell populations, they provide little information on the micro-anatomical relations that contribute to the diagnosis of non-Hodgkin's lymphoma. In addition, the cell populations sampled might not be wholly representative of the bone marrow, because lymphoma cell aggregates might be strongly adherent to stromal cells and reactive populations. These limitations necessitate the examination of bone marrow trephine (BMT) biopsies. Although histological examination of BMT biopsies might confirm the presence of non-Hodgkin's lymphoma, distinguishing morphologically between the various subcategories of low grade non-Hodgkin's lymphoma can be problematical. In particular, the distinction between mantle cell, lymphocytic, and follicle centre lymphomas can be difficult, especially if the peripheral blood is not involved or there are no accessible lymph nodes for examination. New molecular genetic techniques have been established as diagnostic tools for haematological malignancies. The highly sensitive polymerase chain reaction (PCR) can be used to detect clonal B cell populations,1,2 clonal T cell populations,3–5 and chromosomal translocations including t(14;18),6 t(11;14),7 and t(9;22).8 The ability to detect clonal B and T cell populations and translocations is useful for the diagnosis, classification, prognosis, and monitoring of minimal residual disease in non-Hodgkin's lymphoma. Paraffin wax embedded bone marrow trephine (PBMT) biopsies provide a potentially important source of archival DNA for the retrospective molecular analysis of bone marrow. A recent study compared PCR detection of immunoglobulin gene rearrangements with morphological analysis and found the level of detection of immunoglobulin gene rearrangements in bone marrow aspirates to be much lower than expected.9 This was thought to be the result of dilution of the bone marrow cells with peripheral blood, sampling errors, or both. Therefore, the authors suggested that PBMT biopsies might provide a better source of DNA than bone marrow aspirates for the detection of immunoglobulin gene rearrangements. Successful extraction of high molecular weight DNA from frozen bone marrow trephines has been described.10,11 However, most BMT biopsies taken for diagnosis are fixed, decalcified, and embedded in paraffin wax. The only previously published method of DNA extraction from PBMT biopsies is complex and time consuming.12 Only six of the 10 DNA samples extracted by these authors could be amplified to generate a PCR product of 294 base pairs (bp). The inability to amplify a relatively short PCR product from the remaining four DNA samples suggested that the extracted DNA was degraded, or that the samples contained PCR inhibitors. The aim of our study was to establish a simpler method of extraction, suitable for routine use in a diagnostic molecular genetics laboratory. Ideally, this should yield DNA of a consistent quality that can be amplified to produce longer PCR products, including the 600 bp t(11;14) MTCA PCR product.
