Lack of MYD88 L265P in non-immunoglobulin M lymphoplasmacytic lymphoma

Waldenström Macroglobulinemia and Non-IgM-Type Lymphoplasmacytic Lymphoma Are Genetically Similar

INTRODUCTION

Waldenström macroglobulinemia (WM) represents a subset of lymphoplasmacytic lymphoma (LPL) with the immunoglobulin (Ig)M paraprotein. MYD88 L265P and CXCR4 mutations are common mutations in WM patients, and mutations in ARID1A and KMT2D (MLL2) have also been reported. However, little information has been accumulated on genetic changes in LPL with other paraproteins like IgG.

METHODS

We therefore aimed to evaluate genetic differences between WM and LPL with non-IgM paraprotein (non-IgM-type LPL) using targeted next-generation sequencing (NGS) in 20 Japanese patients (10 with WM, 10 with non-IgM-type LPL).

RESULTS

Mutations were detected in ARID1A (10%), CXCR4 (20%), MYD88 (90%), and KMT2D (0%) for WM patients and in ARID1A (10%), CXCR4 (20%), MYD88 (70%), and KMT2D (10%) for non-IgM-type LPL patients. No significant differences were identified. No mutations were detected in NOTCH2, PRDM1, CD274 (PD-L1), PDCD1LG2 (PD-L2), RAG2, MYBBP1A, TP53, or CD79B.

DISCUSSION

Mutant allele frequency in MYD88 L265P did not differ significantly between WM and non-IgM-type LPL. Most mutations detected by NGS were subclonal following MYD88 L265P, although one non-IgM-type LPL patient harbored only CXCR4 S338X mutation. Our NGS analyses reveal genetic characteristics in LPL patients and suggest genetic similarities between these two subsets of LPL, WM and non-IgM-type.

Lymphoplasmacytic lymphoma and marginal zone lymphoma involving bone marrow: A diagnostic dilemma. Useful clinicopathological features to accurate the diagnosis

Lymphoplasmacytic lymphoma (LPL) and marginal zone lymphoma (MZL) frequently infiltrate the bone marrow with similar histologic and immunohistochemical characteristics posing diagnostic problems. Bone marrow biopsy specimens from 25 LPL and 16 MZL have been studied, correlating with clinical, laboratory parameters and the MYD88_p.L265P mutation. Paratrabecular and interstitial infiltration pattern, serum IgM paraprotein levels, and MYD88_p.L265P mutation were significantly more frequent in LPL. Nodular or intrasinusoidal pattern with lymphocytosis and splenomegaly were associated with MZL diagnosis. Different clinical and histological parameters should be collected when LPL or MZL is suspected in bone marrow biopsy specimens.

Detection of MYD88 L265P and WHIM-like CXCR4 mutation in patients with IgM monoclonal gammopathy related disease

A broad spectrum of diseases are associated with IgM monoclonal gammopathy, including Waldenstrom macroglobulinemia (WM), various types of B cell non-Hodgkin's lymphoma (NHL), multiple myeloma (MM), primary amyloidosis (AL), and monoclonal gammopathy of undetermined significance (MGUS); these are called IgM monoclonal gammopathy related diseases (IgM-RD). We investigated MYD88 L265P and WHIM-like CXCR4 mutations in various IgM-RD. Patients with serum immunofixation electrophoresis confirmed IgM monoclonal gammopathy who had enough material for DNA extraction and presented between January 2008 and October 2016 at Peking Union Medical College Hospital were enrolled in this cohort. We performed real-time allele-specific-polymerase chain reaction and Sanger sequencing to explore the presence of MYD88 L265P and WHIM-like CXCR4 mutations. One hundred and twelve patients (64 male and 48 female patients) were included in this retrospective study. The median age at diagnosis was 62 years (range, 30-84 years). In total, 64 patients (57.1%) carried the MYD88 L265P mutation and 14 patients (12.5%) carried the CXCR4 WHIM-like mutation. We identified the MYD88 L265P somatic variant in cases with WM (39/42), MGUS (8/18), NHL (14/41, including 4/13 diffuse large B cell lymphoma (DLBCL), 1/8 mucosa-associated lymphoid tissue, 3/6 splenic marginal zone lymphoma (SMZL), 1/4 chronic lymphocytic leukemia, 2/3 nodal marginal zone lymphoma (NMZL), 1/2 mantle cell lymphoma, 1 Burkitt lymphoma, and 1 B cell NHL that could not be classified), primary AL (2/2), and IgM-PN (1/1). The mutation was absent in five patients with Cryoglobulinemia, two with primary cold agglutinin disease and one with MM. The CXCR4 WHIM-like mutation was present in 10/42 patients with WM, 3/41 with NHL (1 DLBCL, 1 SMZL, and 1 NMZL), and 1/18 patients with IgM MGUS. Among the patients with NHL, those with the mutated MYD88 L265P genotype were younger and had lower level of IgG and IgA than the patients with the wild-type genotype. Patients with the mutated MYD88 L265P genotype with WM and MZL were compared. More male patients, higher levels of IgM and lower levels of LDH were found in the WM group. There was no significant difference in overall survival between the two groups. We present a study of the prevalence of the MYD88 L265P mutation and CXCR4 WHIM-like mutation in IgM RD. The MYD88 L265P mutation may play a key role in the pathogenesis of IgM monoclonal gammopathies. It would be interesting in the future to use MYD88 mutation status to differentiate among diseases.

Lymphoplasmacytic Lymphoma With a Non-IgM Paraprotein Shows Clinical and Pathologic Heterogeneity and May Harbor MYD88 L265P Mutations

OBJECTIVES

Lymphoplasmacytic lymphoma (LPL) with non-immunoglobulin M (IgM) paraproteinemia remains poorly understood. The goal of this study was to investigate the clinicopathologic features of LPL in the bone marrow in patients with immunoglobulin G (IgG) or immunoglobulin A (IgA) paraproteins and evaluate MYD88 L265P mutation status to determine the relationship of these cases to Waldenström macroglobulinemia (WM).

METHODS

Bone marrows from LPL cases with IgG or IgA paraproteins diagnosed between January 1, 2007, and June 30, 2014, were retrieved from the clinical archive. Clinicopathologic features were retrospectively reviewed. MYD88 L265P mutation status was assessed by allele-specific polymerase chain reaction prospectively on all cases.

RESULTS

Of 27 cases, four were reclassified as multiple myeloma, all MYD88 mutation negative. MYD88 L265P mutations were present in 10 (43%) of 23 remaining cases. No association between MYD88 status and bone marrow morphologic or phenotypic features, including the presence of Dutcher bodies, mast cells, expression of CD19 by plasma cells, or hemosiderin, was identified, although these features were present in a subset of cases, similar to WM. Clinical features of WM such as hyperviscosity were uncommon in this group and did not correlate with MYD88 status.

CONCLUSIONS

Non-IgM LPLs are a clinically and pathologically heterogeneous group and often harbor MYD88 L265P mutation, albeit at a lower rate than classic WM. MYD88 status does not correlate with any specific pathologic or clinical manifestations.

Issues in diagnosis of small B cell lymphoid neoplasms involving the bone marrow and peripheral blood. Report on the Bone Marrow Workshop of the XVIIth meeting of the European Association for Haematopathology and the Society for Hematopathology

Small B cell lymphoid neoplasms are the most common lymphoproliferative disorders involving peripheral blood (PB) and bone marrow (BM). The Bone Marrow Workshop (BMW) organized by the European Bone Marrow Working Group (EBMWG) of the European Association for Haematopathology (EAHP) during the XVIIth EAHP Meeting in Istanbul, October 2014, was dedicated to discussion of cases illustrating how the recent advances in immunophenotyping, molecular techniques and cytogenetics provide better understanding and classification of these entities. Submitted cases were grouped into following categories: (i) cases illustrating diagnostic difficulties in chronic lymphocytic leukaemia (CLL); (ii) cases of BM manifestations of small B cell lymphoid neoplasms other than CLL; (iii) transformation of small B cell lymphoid neoplasms in the BM; and (iv) multiclonality and composite lymphomas in the BM. This report summarizes presented cases and conclusions of the BMW and provides practical recommendations for classification of the BM manifestations of small B cell lymphoid neoplasms based on the current state of knowledge.

Lymphoplasmacytic lymphoma and marginal zone lymphoma in the bone marrow: paratrabecular involvement as an important distinguishing feature

OBJECTIVES

The differential diagnosis between bone marrow involvement by lymphoplasmacytic lymphoma (LPL) and marginal zone lymphoma (MZL) is challenging because histology and immunophenotype of both diseases overlap. We revisited the diagnostic pathology features of both diseases in the bone marrow.

METHODS

We studied a series of bone marrow trephine biopsy specimens from 59 patients with Waldenström macroglobulinemia without extramedullary involvement and bone marrow biopsy specimens from 23 patients with well-characterized MZL who also had bone marrow involvement. H&E- and immunoperoxidase-stained sections of bone marrow trephine biopsy specimens as well as flow cytometry and classic cytogenetics performed on aspirations were reviewed. The study was complemented with MYD88 L265P mutation analysis of all samples.

RESULTS

The most distinguishing features of LPL with respect to MZL were focal paratrabecular involvement (P < .001), the presence of lymphoplasmacytoid cells (P < .001) and Dutcher bodies (P < .001), increased numbers of mast cells (P < .001), and the MYD88 L265P mutation (P < .001).

CONCLUSIONS

LPL can be reliably distinguished from MZL in the bone marrow by using a combination of pathology characteristics. Our findings stress the diagnostic importance of using the combination of the following parameters for a correct LPL diagnosis: paratrabecular infiltration, the presence of lymphoplasmacytoid cells and cells with Dutcher bodies, and an increased number of mast cells in addition to the presence of MYD88 mutation.

MYD88 L265P mutation analysis helps define nodal lymphoplasmacytic lymphoma

The diagnosis of lymphoplasmacytic lymphoma is often challenging, especially in extramedullary tissues where the differential diagnosis includes nodal marginal zone lymphoma, splenic marginal zone lymphoma, or other small B-cell neoplasms with plasmacytic differentiation. The MYD88 L265P mutation has been recently identified in >90% of bone-marrow-based lymphoplasmacytic lymphoma, but the incidence of this abnormality and corresponding morphologic correlates in nodal lymphoplasmacytic lymphoma have not been established. We analyzed 87 cases of extramedullary lymphoplasmacytic lymphoma, splenic marginal zone lymphoma, unclassifiable splenic B-cell lymphomas, nodal marginal zone lymphoma with plasmacytic differentiation, and chronic lymphocytic leukemia/small lymphocytic lymphoma with plasmacytic differentiation for MYD88 L265P. Eighteen cases (21%) were positive, including 9/9 (100%) lymphoplasmacytic lymphomas with classic histologic features, 5/12 (42%) cases that met 2008 WHO criteria for lymphoplasmacytic lymphoma but with atypical morphologic features, 3/15 (20%) cases initially considered nodal marginal zone lymphoma with plasmacytic differentiation, and 1/6 (17%) unclassifiable splenic B-cell lymphomas. The presence of MYD88 L265P was associated with IgM paraprotein (P<0.001) and a trend for bone marrow involvement (P=0.09). Each of 44 splenectomy-defined splenic marginal zone lymphomas (19 with plasmacytic differentiation) and the chronic lymphocytic leukemia/small lymphocytic lymphoma with plasmacytic differentiation were negative for the mutation. Morphologic re-review with knowledge of MYD88 mutation status and all available clinical features suggested all MYD88 mutated cases were consistent with lymphoplasmacytic lymphoma (either classic or variant histology), except for one case which remained most consistent with nodal marginal zone lymphoma with plasmacytic differentiation. These results demonstrate the importance of MYD88 mutational analysis in better defining lymphoplasmacytic lymphoma as a relatively monomorphic small B-cell lymphoma with plasmacytic differentiation that may show total nodal architectural effacement and follicular colonization. Cases previously considered lymphoplasmacytic lymphoma that are more polymorphous and are often associated with histiocytes should no longer be included in the lymphoplasmacytic lymphoma category. Clinicopathologic review suggests that although MYD88 mutated non-lymphoplasmacytic lymphoma small B-cell neoplasms exist, they are very uncommon.

MYD88 L265P and CXCR4 mutations in lymphoplasmacytic lymphoma identify cases with high disease activity

Recurrent mutations in MYD88 have been identified in >90% of lymphoplasmacytic lymphoma (LPL). Recently, WHIM (warts, hypogammaglobulinaemia, infections, myelokathexis) syndrome-like mutations in CXCR4 have been described in 28% of LPL cases, and seem to impact clinical presentation and response to therapy. We investigated the presence of the MYD88 L265P mutation in 90 decalcified, formalin-fixed, paraffin-embedded (FFPE) bone marrow (BM) biopsies, including 51 cases of LPL, 14 cases of B-cell chronic lymphocytic leukaemia (CLL), 13 cases of marginal zone lymphoma (MZL) and 12 normal controls. In addition, the C-terminal domain of CXCR4 was sequenced in LPL cases. MYD88 L265P was found in 49/51 (96%) LPL cases and in 1/13 (7·6%) MZL (splenic type), whereas all CLL samples remained negative. The two MYD88 wild type LPL cases were associated with cold agglutinin disease. Mutations in CXCR4 were detected in 17/47 (36·2%) LPL cases, which showed a higher extent of BM infiltration and lower leucocyte counts (P = 0·02), haemoglobin (P = 0·05) and platelet counts (P = 0·01). In conclusion the detection of MYD88 L265P mutation in FFPE samples is reliable and useful for subtyping small B-cell lymphomas in BM biopsies. In addition, the presence of CXCR4 mutations identifies a subgroup of LPL patients with higher disease activity.

Clonotypic analysis of immunoglobulin heavy chain sequences in patients with Waldenström's macroglobulinemia: correlation with MYD88 L265P somatic mutation status, clinical features, and outcome

We performed IGH clonotypic sequence analysis in WM in order to determine whether a preferential IGH gene rearrangement was observed and to assess IGHV mutational status in blood and/or bone marrow samples from 36 WM patients. In addition we investigated the presence of MYD88 L265P somatic mutation. After IGH VDJ locus amplification, monoclonal VDJ rearranged fragments were sequenced and analyzed. MYD88 L265P mutation was detected by AS-PCR. The most frequent family usage was IGHV3 (74%); IGHV3-23 and IGHV3-74 segments were used in 26% and 17%, respectively. Somatic hypermutation was seen in 91% of cases. MYD88 L265P mutation was found in 65,5% of patients and absent in the 3 unmutated. These findings did not correlate with clinical findings and outcome. Conclusion. IGH genes' repertoire differed in WM from those observed in other B-cell disorders with a recurrent IGHV3-23 and IGHV3-74 usage; monoclonal IGHV was mutated in most cases, and a high but not omnipresent prevalence of MYD88 L265P mutation was observed. In addition, the identification of 3 patients with unmutated IGHV gene segments, negative for the MYD88 L265P mutation, could support the hypothesis that an extra-germinal B-cell may represent the originating malignant cell in this minority of WM patients.