Plasmacytomas are characterized by sheets of plasma cells and are usually immature or pleomorphic. In contrast to LPL, the cytoplasmic immunoglobulin is usually IgG. They are usually CD45 [LCA]− and CD20−.
Key features of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia•
Small lymphoid cells and plasmacytoid lymphoid cells;
•CD5−, CD10− B cells;
•Aberrant coexpression of CD20 and CD43;
•Light-chain restriction; and
•Cytoplasmic and surface immunoglobulin.
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Small B-Cell Lymphomas
Rebecca L. King MD, Paul J. Kurtin MD, in Hematopathology [Third Edition], 2018
Clinical Features
Lymphoplasmacytic lymphoma is an uncommon neoplasm of older adults with a slight male predominance. Usually, LPL affects the bone marrow with less frequent involvement of spleen and lymph nodes. Most commonly, it is associated with mutations in the myeloid differentiation primary response gene 88 [MYD88], IgM paraproteinemia, and manifestations of hyperviscosity [Waldenström macroglobulinemia [WM]]. Although WM is defined as LPL with an IgM paraproteinemia of any level, the two terms LPL and WM are not synonymous, and, rarely, LPL can present with non-IgM paraproteins. Some cases of LPL may arise in association with hepatitis C, although other lymphoproliferative disorders can also arise in this setting. Primary cold agglutinin-associated lymphoproliferative disease was previously thought to be a form of LPL. This is no longer the case because newer molecular markers, such as MYD88, are negative in most cold agglutinin-associated lymphoproliferations, suggesting they are a distinct entity.
Lymphoplasmacytic Lymphoma—Fact Sheet
Clinical Features
▪1.5% of nodal lymphomas
▪Median age 7th decade
▪Male predominance
▪IgM paraproteinemia with or without symptoms of hyperviscosity [Waldenström macroglobulinemia] and bone marrow involvement in most cases
▪Slowly progressive or waxing and waning lymphadenopathy in uncommon subset of patients with primarily lymph node–based disease
Morphology
▪Paracortical infiltrates with open lymph node sinuses
▪Diffuse architectural effacement of lymph node
▪Spectrum of small lymphocytes, plasmacytoid lymphocytes, plasma cells, and immunoblasts in varying proportions in each case
▪Abnormal immunoglobulin production: Dutcher bodies, Russell bodies, amyloid or free immunoglobulin light chain deposits
▪Some cases with epithelioid macrophage clusters that obscure presence of lymphoma
Immunophenotype
▪CD19+, CD20+, sIg+, IgM without IgD, rarely IgG or IgA
Monotypic plasma cells in all [defining feature]
▪CD10 and CD5 negative
▪CD43 variably positive
Genetics
▪MYD88 L265P mutations
Prognosis and Therapy
▪Low-intensity single- or multiple-agent chemotherapy
▪Plasma exchange for transient relief of symptoms of hyperviscosity
▪Survival
–Asymptomatic Waldenström macroglobulinemia patients—similar to age-matched controls
–Symptomatic Waldenström macroglobulinemia patents—median survival, 5 to 7 years
–Lymph node–based disease without Waldenström macroglobulinemia—median survival, 4 years
Differential Diagnosis
▪Reactive lymphoid hyperplasia, particularly autoimmune disease–associated lymphadenitis, IgG4-related sclerosing/autoimmune disorder, and Castleman disease types with abundant plasma cells
▪Chronic lymphocytic leukemia/small lymphocytic lymphoma
▪Mantle cell lymphoma
Follicular lymphoma, particularly those with plasma cell differentiation
▪Nodal marginal zone B-cell lymphoma
▪Splenic marginal zone B-cell lymphoma
▪Extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue
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Monoclonal Gammopathies: Glomerular and Tubular Injuries
M.M. Picken, in Pathobiology of Human Disease, 2014
Waldenström Macroglobulinemia
Waldenström macroglobulinemia is a rare clinicopathologic syndrome associated with an uncontrolled clonal proliferation of terminally differentiated B lymphocytes [lymphoplasmacytic lymphoma], IgM paraprotein, and increased blood viscosity. Renal lesions are related either to lymphoplasmacytic infiltration or to deposition of the paraprotein. Typically, there are amorphous, at times massive, PAS-positive subendothelial or intraluminal deposits that are positive for IgM-κ. Most of the capillary thrombi are electron dense and amorphous [Figure 17]. Waldenström macroglobulinemia can be seen in patients with amyloidosis and types I and II cryoglobulinemia and there is a significant morphological overlap with cryoglobulinemic nephropathy. Waldenström macroglobulinemia is indolent in nature and, while it is incurable, it is treatable. It generally occurs in older patients [median age of 63–70 years]. Although IgM paraprotein is found in 16% of all myeloma patients, only