[1401] Pyrosequencing for MYD88 L265P Mutation Discriminates between Lymphoplasmacytic Lymphoma and Marginal Zone Lymphoma

Giovanni Insuasti-Beltran, Stella Wenceslao, Huining Kang, James M Gale, David R Czuchlewski. University of New Mexico, Albuquerque, NM; TriCore Reference Laboratories, Albuquerque, NM

Background: Lymphoplasmacytic lymphoma (LPL) and marginal zone lymphoma (MZL) are well-defined clinicopathological entities. However, differentiation between LPL and MZL can sometimes be difficult due to overlapping clinical, morphological, immunophenotypic, and cytogenetic features. Recent studies using whole genome sequencing have identified a somatic mutation in the myeloid differentiation primary response gene (MYD88) in the majority of LPL. This mutation results in a change at amino acid position 265 from leucine to proline (L265P). We developed a rapid and inexpensive pyrosequencing assay for the MYD88 L265P mutation and assessed its discriminatory power to differentiate LPL from MZL.
Design: We sequenced the MYD88 gene region using pyrosequencing in 46 previously diagnosed cases of LPL and 55 cases of MZL (10 nodal subtype, 14 splenic subtype, and 31 extranodal subtype) from formalin-fixed paraffin-embedded tissue blocks found in our archived files. Sanger sequencing was performed in a subset of cases (n=30) for confirmation of results.
Results: The MYD88 L265P mutation was identified in 33 out of 46 cases of LPL (72%). In contrast, this mutation was present in only 3/55 cases of MZL (5%). This difference was extremely significant (p<0.001), with a clinical sensitivity of 72% and clinical specificity of 95% to discriminate between LPL and MZL (PPV= 92%, NPV=80%). There was 100% concordance between pyrosequencing and traditional Sanger sequencing.
Conclusions: Based on our evaluation of 101 cases, this study confirms that the MYD88 L265P mutation is highly prevalent in LPL and can be used to differentiate LPL from MZL at the molecular level. Our novel pyrosequencing assay for MYD88 L265P is robust and may prove clinically useful.
Category: Hematopathology

Monday, March 4, 2013 8:45 AM

Proffered Papers: Section C, Monday Morning


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