#00060667

A 59-year-old man suspected of acute transplant rejection after a recent heart allograft (<1 month) was treated with intensive immunosuppressive therapy. The clinical examination found renal failure without lymphadenopathy, organomegaly, or osteolytic lesions.The complete blood count, initially normal before allograft, showed anemia, thrombopenia, and a leukocytosis (22 × 10 9/L) with rouleau formation and 67% circulating plasma cells with a round eccentric nucleus, clumped chromatin, and abundant basophilic cytoplasm on the blood film (panel A). Serum and immunofixation electrophoresis revealed 23.1 g/L of serum immunoglobulin A (IgA) monoclonal protein. Laboratory data revealed elevated serum lactate dehydrogenase and β-2 microglobulin levels, moderate renal insufficiency, and a normal calcemia level. Epstein-Barr virus (EBV) load was 4.2 × 10 6 copies per mL. Bone marrow examination counted 46% plasma cells. Immunophenotyping showed surface expression of CD45 intermediate, CD38, CD138, CD19, CD27, CD43, CD81, HLA-DR weak, and a lack of CD34, CD10, CD20, CD28, CD56, and CD117. The detection of monotypic cytoplasmic κ light chain immunoglobulin without surface expression (panel B) and clonal immunoglobulin heavy chain gene rearrangement molecular analysis was consistent with B-cell clonality. The karyotype was normal. Unfortunately, the patient died 6 weeks after diagnosis. We report a very unusual case of an EBV-associated monotypic posttransplant lymphoproliferative disorder exhibiting plasmacytic features in leukemic phase.