Posttransplantation lymphoproliferative disorder (PTLD) is an uncommon but often fatal complication of solid organ transplantation that occurs in approximately 3% of patients. To determine the relative importance and relationship of potential risk factors for PTLD before transplantation (i.e., Epstein-Barr virus [EBV] serostatus of the recipient and the cytomegalovirus [CMV] sero-status of the recipient and the potential donor) and the principal risk factor after transplantation (immunosuppression with antilymphocyte antibody), we analyzed the findings for the first 381 consecutive adult nonrenal transplant recipients seen at Mayo Clinic. In the absence of the other risk factors, the incidence rate of PTLD for EBV-seronegative recipients was 24 times higher (95% confidence interval [CI]: 6.2, 89) than that for EBV-seropositive recipients. The additional risk factors of therapy with OKT3 for rejection and CMV seromismatch (i.e., a negative recipient and a positive donor) each further amplified this risk four- to sixfold. Together, all three risk factors acted synergistically to increase the incidence rate of fatal and/or CNS PTLD by a factor of 654 (CI: 368, 1,162) compared with the low incidence rate (.458 cases per 100 person years) when none of these risk factors were present. Pretransplantation determination of recipient EBV and CMV serostatus can identify a subgroup of patients whose risk for severe PTLD may preclude transplantation.

In two patients with classic Hodgkin's disease and non-Hodgkin's B-cell lymphoma, we identified a common B-cell precursor, probably a germinal-center B-cell, for both lymphomas. This finding suggests that the two types of lymphoma underwent both shared and distinct transforming events and provides proof of the B-cell derivation of Reed-Sternberg cells in classic Hodgkin's disease.

Among the four subtypes of Hodgkin disease (HD), lymphocyte-predominant (LP) HD is now generally considered as a separate entity. The B cell nature of the typical Hodgkin and Reed–Sternberg (HRS) cells and their variants (L and H, lymphocytic and histiocytic cells) in LP HD has long been suspected, but the question of whether these cells represent a true tumor clone is unclear. We previously demonstrated clonal Ig gene rearrangements in one case of LP HD. In the present study, five cases of LP HD were analyzed by micromanipulation of single HRS cells from frozen tissue sections and DNA amplification of rearranged Ig heavy chain genes from those cells. Clonal V gene rearrangements harboring somatic mutations were detected in each case. In three cases ongoing somatic mutation was evident. This shows that HRS cells in LP HD are a clonal tumor population derived from germinal center B cells. The pattern of somatic mutation indicates that HRS cells in LP HD are selected for antibody expression. This, and the presence of ongoing mutation discriminates LP from classical HD.