Lymphoplasmacytic lymphoma and Waldenström macroglobulinaemia: clinicopathological features and differential diagnosis.

Lymphoplasmacytic lymphoma (LPL) represents a distinct type of mature B-cell lymphoma with a substantial subset of cases being associated with Waldenström macroglobulinaemia (WM), defined as primarily bone marrow involvement and the presence of an IgM monoclonal paraprotein. MYD88 L265P mutation, although not specific, is present in the vast majority (>90%) of LPL cases and sheds light on the potential pathogenesis of this disease. This review offers an overview of current knowledge on the pathogenesis, clinical presentations, histological features and immunophenotype of LPL and WM. In addition, the differential diagnosis of LPL and WM from other mature B cell neoplasms is highlighted with a focus on distinction from marginal zone lymphoma and plasma cell neoplasms.