Plasmacytic posttransplant lymphoproliferative disorder with hyperviscosity syndrome in a child after liver transplant

BCR signaling is required for posttransplant lymphoproliferative disease in immunodeficient mice receiving human B cells

Posttransplant lymphoproliferative disease (PTLD) is a major therapeutic challenge that has been difficult to study using human cells because of a lack of suitable models for mechanistic characterization. Here, we show that ex vivo-differentiated B cells isolated from a subset of healthy donors can elicit pathologies similar to PTLD when transferred into immunodeficient mice. The primary driver of PTLD-like pathologies were IgM-producing plasmablasts with Epstein-Barr virus (EBV) genomes that expressed genes commonly associated with EBV latency. We show that a small subset of EBV+ peripheral blood-derived B cells expressing self-reactive, nonmutated B cell receptors (BCRs) expand rapidly in culture in the absence of BCR stimulation. Furthermore, we found that in vitro and in vivo expansion of EBV+ plasmablasts required BCR signaling. Last, treatment of immunodeficient mice with the BCR pathway inhibitor, ibrutinib, delays onset of PTLD-like pathologies in vivo. These data have implications for the diagnosis and care of transplant recipients who are at risk of developing PTLD.

The clinical and pathological features of plasma cell myeloma post solid organ transplantation

Plasma cell neoplasms (PCNs), comprising plasma cell myelomas (PCMs) and plasmacytomas, which occur after solid organ transplantation, represent rare subtypes of monomorphic post-transplant lymphoproliferative disorders (M-PTLDs). Data regarding the clinical and pathological features of post-transplant (PT)-PCMs are limited. To gain a better understanding of disease biology, we performed comprehensive immunophenotypic analysis, reviewed cytogenetic analysis results and evaluated clinical outcomes of PT-PCMs diagnosed and treated at our institution. Fifteen PT-PCM (M: F - 4:1) and two PT-MGUS (two males) cases were identified. The median age of PT-PCM patients was 68 years (29-79 years) and PCMs presented at a median of 9.7 years (0.5-24.7 years) after transplantation. The PT-PCMs accounted for 11.6% of all M-PTLDs and the period prevalence was 9/3108 (0.29%), 3/1071 (0.28%), 2/1345 (0.15%) and 1/878 (0.11%) post kidney, heart, liver and lung transplantation. Lytic bone disease was observed in 1/11 (9%) patients. Marrow plasma cell infiltration ranged from 10%-70% (median 20%), with 10/15 (67%) and 5/15 (33%) cases manifesting immature and plasmablastic morphology. The immunophenotype of all cases and cytogenetic abnormalities, identified in 60% of cases, were similar to multiple myeloma (MM) of immunocompetent individuals. All PT-PCMs were EBER negative. Ten of 11 (91%) patients with active MM were treated, all with proteasome inhibitor-based therapy. Treatment response and 5-year overall survival (54.5%) was comparable to MM of immunocompetent individuals. However, the survival of patients with plasmablastic PCMs was inferior to those with immature PCMs. 0ur findings indicate PT-PCMs to be predominantly late onset PTLDs that have similar clinicopathologic characteristics as conventional MM.