Genetics- and immune-related factors in the pathogenesis of lymphoplasmacytic lymphoma/ Waldenström's macroglobulinemia

Waldenström's Macroglobulinemia: An Exploration into the Pathology and Diagnosis of a Complex B-Cell Malignancy

After 77 years since the initial description, Waldenström macroglobulinemia (WM) remains as a bone marrow neoplastic disorder with lymphoplasmacytic differentiation oversecreting a monoclonal immunoglobulin M (IgM). However, many biological and genetic aspects of this entity have been unraveled and it is now easy to correctly diagnose patients with this illness. The diagnosis requires the presence of a monoclonal IgM component and bone marrow lymphoid infiltration must be demonstrated. In addition, other small B-cell lymphoid neoplasms with plasma cell differentiation must be discarded. Although the clinical picture is highly heterogeneous, the diagnosis is much easier today compared to the past, since now we can demonstrate the presence of somatic mutations, especially the L265P mutation in the MYD88 gene, highly characteristic of WM (>90% of the patients), followed by the WHIM-like mutations in the CXCR4 gene (~35%). The identification of these mutations is very important, because they can modulate the response to new treatments with Bruton's tyrosine kinase (BTK) inhibitors. Thus, the conventional prognostic factors that predict the outcome of these patients (anemia, thrombopenia, high M component, high B2M, and advanced age), must be complemented with the genetic evaluation of the patient, that can help us in the prediction of the risk of transformation from asymptomatic to symptomatic forms (Del6q) and/or from indolent forms of the disease to aggressive lymphomas (CD79b mutations).

How to manage Waldenstrom's macroglobulinemia

Waldenstrom's macroglobulinemia (WM) is very distinct from other indolent lymphoma subtypes: by definition it is accompanied by a monoclonal IgM gammopathy; it presents always with bone marrow infiltration and often with clinical symptoms such as neuropathy or hyperviscosity. These disease characteristics and the frequently advanced age of the WM patient pose a major challenge to the treating clinician even today. Recently, there has been not only substantial progress in our understanding of the biology of WM, but we have also significantly improved our tools to prognostify and to treat patients with this disease. This review summarizes our current knowledge about WM and aims at offering a guideline for the clinical management of patients with this lymphoma subtype, covering questions on how to manage diagnosis, prognostification and treatment based on the most recent data.

Familial aggregation of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia with solid tumors and myeloid malignancies

Lymphoplasmacytic lymphoma (LPL)/Waldenström macroglobulinemia (WM) is a B-cell disorder resulting from the accumulation, predominantly in the bone marrow, of clonally related lymphoplasmacytic cells. LPL/WM is a very rare disease, with an incidence rate of 3-4 cases per million people per year.Currently, the causes of LPL/WM are poorly understood; however, there are emerging data to support a role for immune-related factors in the pathogenesis of LPL/WM. In addition, data show that genetic factors are of importance in the etiology of LPL/WM. In this paper, we will review the current knowledge about familiality of LPL/WM and provide novel data on solid tumors and myeloid malignancies in first-degree relatives of LPL/WM patients.

Waldenström macroglobulinemia: a review of the entity and its differential diagnosis

The definition of Waldenström macroglobulinemia (WM), originally described in 1944, has been refined substantially over time. The current fourth edition of the World Health Organization of lymphoid neoplasms, in large part, adopted criteria proposed for WM at a consensus conference in 2002. WM is defined as lymphoplasmacytic lymphoma involving the bone marrow associated with a serum immunoglobulin (Ig) M paraprotein of any concentration. Morphologically, WM is composed of a variable mixture of lymphocytes, plasmacytoid lymphocytes, and plasma cells. Immunophenotypically, the neoplastic cells express monotypic IgM and light chain: B lymphocytes express pan-B-cell antigens and surface Ig are usually negative for CD5 and CD10; and plasma cells are typically positive for CD138, CD38, CD45, cytoplasmic Ig, and CD19 (in a substantial subset of cases). The putative cell of origin of WM is a postantigen selected memory B-cell that has undergone somatic hypermutation. The most common cytogenetic abnormality in WM is del(6q), usually in the region 6q23-24.3, present in 40% to 50% of cases. IGH gene translocations are rare and recurrent chromosomal translocations or gene aberrations have not been identified in WM. Here, we provide a historical perspective of WM, review clinical and pathologic aspects of the disease as it is currently defined, and discuss some practical issues in the differential diagnosis of WM that pathologists encounter in the signout of cases.

Blood transfusions and the subsequent risk of hematologic malignancies

BACKGROUND

Blood transfusions are associated with viral transmission and immunomodulation, perhaps increasing subsequent risk of hematologic malignancies (HMs). Prior studies of transfusion recipients have lacked details on specific HM subtypes.

STUDY DESIGN AND METHODS

Risk of HM after blood transfusion was evaluated in a US population-based case-control study (77,488 elderly HM cases identified through cancer registries, 154,509 controls). Transfusions were identified using linked Medicare hospitalization claims. Polytomous logistic regression was used to calculate odds ratios (ORs) associating transfusion and HM subtypes by features suggestive of a causal relationship.

RESULTS

A history of transfusion was present in 7.9% of HM cases versus 5.9% of controls. Associations for most HM subtypes suggested reverse causality: ORs were elevated only during the shortest latency periods; ORs for unspecified anemia and gastrointestinal bleeding, which may be related to undiagnosed HM, were stronger than for surgeries, which are unlikely to be related to HM; and/or there was no dose response. In contrast, risk for lymphoplasmacytic lymphoma (1397 cases) was elevated at long latency (OR, 1.56 at 10+ years after transfusion), after transfusions related to surgeries (OR, 1.22-1.47), and in a dose-response relationship with number of transfusion-related hospitalizations (OR, 1.53 with one hospitalization; OR, 1.80 with two or more hospitalizations, p trend < 0.0001). Risk for marginal zone lymphoma (1915 cases) was also elevated at 10+ years after transfusion (OR, 1.80).

CONCLUSION

Consistent with prior studies, blood transfusions did not increase risk of most HM subtypes. Patterns of elevated risk for lymphoplasmacytic and marginal zone lymphomas suggest an etiologic role for transfusion.