Simultaneous Occurrence of Angioimmunoblastic T-cell Lymphoma and Plasma Cell Leukemia

A 73-yr-old man was evaluated for fever and multiple palpable nodules in his neck and inguinal areas. Biopsy of a cervical lymph node demonstrated polymorphic infiltrates including Tcells with abundant clear cytoplasm (clear cells), follicular dendritic cells, and plasma cells in the background of prominent arborizing high endothelial venules. The involved lymph node had typical histological and immunohistochemical properties characteristic of angioimmunoblastic T-cell lymphoma (AITL), except for the absence of CD10 expression. Lymphoplasmacytic lymphoma was excluded. A staging computed tomographic scan showed generalized lymphadenopathy in his chest, abdomen, and pelvis, as well as hepatosplenomegaly. Laboratory findings demonstrated the presence of leukocytosis (30.5×10/L). A peripheral blood (PB) smear revealed rouleaux formations and numerous circulating plasma cells, with plasmacytoid lymphocytes accounting for 25% of all nucleated cells. Protein electrophoresis and immunofixation studies of serum indicated IgMκ monoclonal gammopathy (IgM level, 53.8 g/L; normal range, 0.4-2.3 g/L). A bone marrow (BM) biopsy revealed 80% hypercellularity with focal clusters of CD3 malignant T-cells and diffuse CD138 clonal plasma cells at proportions of 10% and 30%, respectively (Fig. 1). The CD3 T-cells were mediumsized lymphoid cells with moderate amounts of clear cytoplasm and slightly indented nuclei with coarse and condensed chromatin. In concordance with the monoclonal gammopathy found in the serum, immunohistochemical analysis of mixed plasma cells revealed a pattern restricted to κ light chain reactivity. Rare scattered cells were found positive for Epstein-Barr virus (EBV) by using in situ hybridization. Analysis for the expression of CD20 indicated relatively few mature B-cells. Flow cytometry analysis of circulating lymphocytes revealed a B-cell population expressing CD19, but the cells lost CD20 without surface Ig expression (25.12% of total events). Instead, these cells intensely expressed CD38 with a fraction of the cells also expressing CD138. Almost all CD38 cells exhibited cytoplasmic κ restriction. In addition to the clonal plasma cells, T-cells that co-expressed CD3 and CD4 were also found to be positive for the known T-cell antigens CD2 and CD5 but negative for CD7. Consistent with the immunohistological findings from primary lymph node, T-cells were found to be negative for CD10. T-cells with immunophenotypic variation were considered AITL cells and comprised up to 0.25% of the total gated events. Representative scatter plots of the immunophenotypic findings obtained from the flow cytometry analysis are shown in Fig. 2. PCR analysis of the T-cell receptor gamma chain gene (TCRγ) demonstrated a clonal rearrangement that confirms T-cell clonality. Molecular analyses for the TCRγ rearrangement was performed through PCR by using a mixture of consensus V and J