Diagnostic approach of an IgM monoclonal gammopathy and clinical importance of gene MYD88 L265P mutation

Abstract

A monoclonal IgM peak suggests a MW but other B lymphoproliferatives disorders should be excluded. Even if the L265P mutation is frequent in the LLP/MW, it is not specific. A precise diagnosis requires collating clinical, histological, immunophenotypical and genetical data.

Immunoglobulin M (IgM) multiple myeloma versus Waldenström macroglobulinemia: diagnostic challenges and therapeutic options: two case reports

“…In contrast, many reports underline the importance of MYD88 L256P mutation in patients with WM as the pathognomonic sign [5]. However, according to European Society for Medical Oncology clinical practice guidelines [8], MYD88 mutation alone cannot be considered diagnostic for WM.…”

“…The presence of an MYD88 mutation is usually absent in IgM MM; in contrast, it is pathognomonic in WM [5]. The presence of translocation t (11; 14) detected by fluorescence in situ hybridization (FISH) is shown in IgM MM but is absent in WM [6].…”

MYD88 in the driver’s seat of B-cell lymphomagenesis: from molecular mechanisms to clinical implications

“…2,3,18, The highest prevalence of MYD88(L265P) is found in lymphoplasmacytic lymphoma/WM, with approximately 85% of the patients being affected. 18,[22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] In DLBCL, the prevalence of MYD88(L265P) is highest (range, 44% to 73%) in extranodal DLBCL, in immune-privileged sites, 96 such as primary DLBCL of the central nervous system 18,22,23,[86][87][88]96 and primary testicular lymphoma, 22,23,96,108 primary cutaneous DLBCL, leg type, 22,71,89-91 orbital/vitreoretinal DLBCL, 22,97,98 intravascular large B-cell lymphoma, 95 and primary breast DLBCL. 22,99 The high prevalence of MYD88(L265P) in extranodal site-specific lymphomas, lymphoplasmacytic lymphoma, and WM may provide an indication for the origin of these lymphomas.…”