Giovanni Insuasti-Beltran, James M Gale, Carla S Wilson, Kathryn Foucar, David R Czuchlewski1. 1. From the Department of Hematopathology/Molecular Genetics Pathology, University of Arkansas for Medical Sciences, Little Rock (Dr Insuasti-Beltran); TriCore Reference Laboratories, Albuquerque, New Mexico (Dr Gale); and the Department of Pathology, University of New Mexico, Albuquerque (Drs Wilson, Foucar, and Czuchlewski).
Abstract
CONTEXT: Lymphoplasmacytic lymphoma (LPL), marginal zone lymphoma (MZL), and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) are well-defined clinicopathologic entities. However, distinguishing LPL from MZL and from atypical cases of CLL can sometimes be difficult because of overlapping features. Recent studies have identified a recurrent L265P mutation in the MYD88 gene in most cases of LPL. Although this represents a promising diagnostic marker for LPL, the mutation is also reported in rare cases of MZL and CLL (as well as other types of B-cell lymphoma). Detection rates for this mutation have varied depending on the analytic methodology. OBJECTIVE: To assess the diagnostic utility of MYD88 L265P mutation in diagnosing low-grade B-cell lymphomas. DESIGN: We developed a novel pyrosequencing assay for the MYD88 L265P mutation and assessed its diagnostic utility in 317 cases of low-grade B-cell lymphoma (45 LPL [14%], 53 MZL [17%], and 219 CLL [69%]). We incorporated formal clinical and pathologic review of selected cases to ensure the most accurate diagnosis and subclassification. RESULTS: The MYD88 L265P mutation was identified in 43 cases of LPL (96%), including 3 nonimmunoglobulin-M LPL cases. In contrast, the mutation was present in only 2 cases of MZL (4%), and 5 cases of CLL (2%). Thus, pyrosequencing for the MYD88 L265P mutation demonstrates a high clinical sensitivity and specificity to distinguish LPL from MZL and CLL. CONCLUSIONS: This study confirms the strong association of the MYD88 L265P mutation with LPL, as well as the existence of rare cases of small B-cell lymphoma that complicate this association.
CONTEXT: Lymphoplasmacytic lymphoma (LPL), marginal zone lymphoma (MZL), and chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) are well-defined clinicopathologic entities. However, distinguishing LPL from MZL and from atypical cases of CLL can sometimes be difficult because of overlapping features. Recent studies have identified a recurrent L265P mutation in the MYD88 gene in most cases of LPL. Although this represents a promising diagnostic marker for LPL, the mutation is also reported in rare cases of MZL and CLL (as well as other types of B-cell lymphoma). Detection rates for this mutation have varied depending on the analytic methodology. OBJECTIVE: To assess the diagnostic utility of MYD88L265P mutation in diagnosing low-grade B-cell lymphomas. DESIGN: We developed a novel pyrosequencing assay for the MYD88L265P mutation and assessed its diagnostic utility in 317 cases of low-grade B-cell lymphoma (45 LPL [14%], 53 MZL [17%], and 219 CLL [69%]). We incorporated formal clinical and pathologic review of selected cases to ensure the most accurate diagnosis and subclassification. RESULTS: The MYD88L265P mutation was identified in 43 cases of LPL (96%), including 3 nonimmunoglobulin-M LPL cases. In contrast, the mutation was present in only 2 cases of MZL (4%), and 5 cases of CLL (2%). Thus, pyrosequencing for the MYD88L265P mutation demonstrates a high clinical sensitivity and specificity to distinguish LPL from MZL and CLL. CONCLUSIONS: This study confirms the strong association of the MYD88L265P mutation with LPL, as well as the existence of rare cases of small B-cell lymphoma that complicate this association.
Authors: Ruben A L de Groen; Anne M R Schrader; Marie José Kersten; Steven T Pals; Joost S P Vermaat Journal: Haematologica Date: 2019-11-07 Impact factor: 9.941