<prompt> MYD88 L265P mutation is seen inWaldenstrom macroglobulinemiaMultiple myelomaBurkitts lymphomaB cell disorders  <response>: Ans. A. Waldenstrom macroglobulinemiaExplanationMYD88L 265P is expressed in 90 to 95 of WM cases when more sensitive allele-specific PCR has been employed.Waldenstroms macroglobulinemia WM:It is a IgM-secreting lymphoplasmacytic lymphoma LPL.Clinical manifestations:Cytopenia resulting from bone marrow infiltration by lymphoplasmacytic cells,Paraprotein-related cryoglobulinemia,The cold agglutinin syndrome,Demyelinating neuropathySymptomatic hyperviscosity.Oncogenic basis: not been defined.Familial clustering of Waldenstroms macroglobulinemia and other B-cell disorders suggests that genetic factors play a role in certain patients.IgM monoclonal gammopathy of unknown significance MGUS is characterized by the presence of a monoclonal IgM protein and the absence of bone marrow disease involvement on histologic examination. IgM MGUS can progress to Waldenstroms macroglobulinemia or other B-cell lymphoproliferative disordersMYD88 L265P is a commonly recurring mutation in patients with Waldenstroms macroglobulinemia that can be useful in differentiating Waldenstroms macroglobulinemia and non-IgM LPL from B-cell disorders that have some of the same features. 