PCR analysis of IgH-gene rearrangements in small lymphoid infiltrates microdissected from sections of paraffin-embedded bone marrow biopsy specimens.

The differentiation of benign lymphoid infiltrates from nodular infiltrates of B-cell lymphoma is difficult in bone marrow (BM) biopsy specimens taken from patients with non-Hodgkin's lymphoma (NHL). We investigated whether the determination of clonality by polymerase chain reaction (PCR) analysis of the immunoglobulin heavy chain (IgH) genes could be of help for the distinction of benign and malignant lymphoid infiltrates. BM biopsy specimens of 28 patients were studied, comparing PCR of entire bone marrow sections with microdissected nodular lymphoid infiltrates. Patients were divided into 4 groups according to morphologic criteria: group 1 (n = 12), positive for B-NHL infiltration; group 2 (n = 5), suspicious for infiltration by known B-NHL; group 3 (n = 5), morphologically benign infiltrates in patients with B-NHL; group 4 (n = 6), benign lymphoid infiltrates in patients without history of B-NHL. PCR products were analyzed using polyacrylamide gels and a fragment length analysis system (Genescan). PCR of whole sections showed clonal amplification products in all cases of group 1 and 1 case of group 2. PCR analysis from microdissected nodular infiltrates showed the presence of a clonal B-cell population in 5 additional cases of groups 2 and 4. In 3 of these cases, clonal rearrangements of corresponding size were obtained from the primary lymphoma biopsy specimens. None of the cases of group 3 showed evidence of a clonal population with either technique. The results indicate that microdissection of small nodular lymphoid infiltrates from paraffin-BM sections increases the sensitivity of IgH gene rearrangement analysis. To avoid detection of biologically irrelevant clonal populations, comparison of PCR products obtained from the BM and the primary lymphoma biopsy is advisable.