The majority of patients with LPL present with anemia. Most have an IgM paraprotein. Rarely both IgM and IgG or other paraproteins may be present. About 30% of patients present with hyperviscosity and features of WM. In a proportion of cases, some cells within the infiltrate have intranuclear cytoplasmic pseudo-inclusions (Dutcher bodies). Differentiation of LPL from bone marrow involvement by marginal zone lymphoma (MZL) with plasmacytic differentiation is particularly challenging, and a diagnosis of MZL at another site should be excluded before arriving at a diagnosis of LPL. There are no characteristic/consistent cytogenetic abnormalities among LPL [1, 2].1

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Figure 1. The images from bone marrow aspirate and trephine along with immunohistochemical investigations represent a typical case of lymphoplasmacytic lymphoma (LPL)/Waldenström's macroglobulinaemia (WM). A woman in her 60s presented with hyperviscosity and her routine blood counts showed anaemia with hemoglobin of 8.2 g/dL, red cell count of 2.91 × 1012/L and a hematocrit of 0.254. The remainder of the blood counts was within the normal range, and her erythrocyte sedimentation rate was markedly elevated at 118 mm/hr. She was found to have a paraprotein of 40 g/L of IgM Kappa type. Her bone marrow aspirate (a–c) shows excess of small lymphoid cells with relatively coarse chromatin, some with indented nuclei. The small lymphoid cells are accompanied by plasma cells and cells with morphological features overlapping between plasma cells and lymphoid cells—plasmacytoid lymphocytes. The bone marrow trephine biopsy showed paratrabecular lymphoid infiltrates (d and e) and areas with a dense diffuse infiltrate. In a bone marrow trephine biopsy, a paratrabecular infiltrate of small lymphoid cells raises the possibilities of bone marrow involvement by follicular lymphoma (FL) and of LPL. Evaluation of the infiltrate at higher magnification both in the areas of paratrabecular and diffuse involvement (e and f) showed the characteristic mix of small lymphoid cells (with round or minimally cleaved nuclei and coarse chromatin), plasma cells, and plasmacytoid lymphocytes. The infiltrate was also accompanied by mast cells of normal morphology. The small lymphoid cells and the plasmacytoid lymphocytes were positive for CD20 (g), MUM1 (weak) (h), CD79a, VS38c (i), and IgM (j). The lymphoid cells were negative for CD138, IgD, CD3, CD5, CD10, CD23, cyclin D1, EMA, and CD56. The plasma were positive for CD138, CD79a, MUM1 (1h), VS38c (1i), IgM (j), and EMA. They were negative for CD20, cyclin D1, and CD56. The small lymphoid cells, plasmacytoid lymphocytes, and the plasma cells were kappa light chain restricted. VS38c showed intense diffuse cytoplasmic positivity in the plasma cells, whereas the small lymphoid cells and the plasmacytoid lymphocytes showed granular cytoplasmic positivity. VS38c is an antibody developed to recognize plasma cells, and the antigen is localized to the rough endoplasmic reticulum. The intensity of MUM1 expression was strong in plasma cells and more heterogeneous among lymphoid cells, possibly dependent on the degree of plasmacytoid differentiation.

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  2. References
  • 1
    Owen RG,Treon SP,Al-Katib A, et al. Clinicopathological definition of Waldenstrom's macroglobulinemia: Consensus panel recommendations from the Second International Workshop on Waldenstrom's macroglobulinemia. Semin Oncol 2003; 30: 110115.
  • 2
    Swerdlow SH,Berger F,Pileri SA, Harris NL, Jaffe ES, Stein H. Lymphoplasmacytic lymphoma. In: SwerdlowSH, CampoE, HarrisNL, Jaffe ES, Pileri SA, Stein H, Thiele J, Vardiman JW (ed): WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. Lyon, France: IARC; 2008. pp 194195.