Molecular analysis of the immunoglobulin V-H gene rearrangement in a primary cutaneous immunoblastic B-cell lymphoma by micromanipulation and single-cell PCR

The immunoglobulin V-H gene rearrangement in a primary cutaneous, large-cell (centroblastic and immunoblastic) B-cell lymphoma was analyzed using a micromanipulation/single-cell polymerase chain reaction technique. In all single B cells obtained from CD20-stained skin sections that gave a polymerase chain reaction product (eight of 27 in biopsy I), the same V(H)DJ(H) rearrangement, consisting of DP-54-DIR1-J(H)3a genes, was detected, with no intraclonal nucleotide diversity. Comparison with the most closely related germline counterpart showed significantly altered complementarity determining gene regions as a result of somatic mutations, suggesting an antigen-driven selection and expansion of this particular B-cell clone. Interestingly, in a biopsy obtained from the patient 9 mo later, during disease progression (deep muscle infiltration), the lymphoma cells again contained the same V(H)DJ(H) gene rearrangement (six of 18 in biopsy II) without any further somatic mutations. Therefore, it is suggested that the cutaneous lymphoma characterized throughout this study descended from postgerminal center B-cells.