Waldenstrom macroglobulinemia involving extramedullary sites: morphologic and immunophenotypic findings in 44 patients

Diagnosis and management of Waldenström macroglobulinaemia-A British Society for Haematology guideline

SCOPE

The objective of this guideline is to provide healthcare professionals with clear guidance on the management of patients with Waldenström macroglobulinaemia. In individual patients, circumstances may dictate an alternative approach.

METHODOLOGY

This guideline was compiled according to the British Society for Haematology (BSH) process at http://www.b-s-h.org.uk/guidelines/proposing-and-writing-a-new-bsh-guideline/. Recommendations are based on a review of the literature using Medline, Pubmed, Embase, Central, Web of Science searches from beginning of 2013 (since the publication of the previous guidelines) up to November 2021. The following search terms were used: Waldenström('s) macroglobulin(a)emia OR lymphoplasmacytic lymphoma, IgM(-related) neuropathy OR cold h(a)emagglutinin disease OR cold agglutinin disease OR cryoglobulin(a)emia AND (for group a only) cytogenetic OR molecular OR mutation OR MYD88 OR CXCR4, management OR treatment OR transfusion OR supportive care OR plasma exchange OR plasmapheresis OR chemotherapy OR bendamustine OR bortezomib OR ibrutinib OR fludarabine OR dexamethasone OR cyclophosphamide OR rituximab OR everolimus, bone marrow transplantation OR stem cell transplantation. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) nomenclature was used to evaluate levels of evidence and to assess the strength of recommendations. The GRADE criteria can be found at http://www.gradeworkinggroup.org. Review of the manuscript was performed by the British Society for Haematology (BSH) Guidelines Committee Haemato-Oncology Task Force, the BSH Guidelines Committee and the Haemato-Oncology sounding board of BSH. It was also on the members section of the BSH website for comment. It has also been reviewed by UK Charity WMUK; these organisations do not necessarily approve or endorse the contents.

Serous fluids and hematolymphoid disorders

Diagnosing hematolymphoid neoplasm by evaluating fine-needle aspiration (FNA) cytology sample is controversial and requires experience and clinical skills. This concept becomes more challenging when evaluating hematolymphoid neoplasm in body fluid. Differentiating between low-grade lymphoma and reactive lymphocytes is often difficult by morphology alone as reactive lymphoid cells may acquire activation morphology from being exposed to different cytokines within the body fluid. However, in most cases there are specific features that may aid in differentiating small reactive from non-reactive lymphocytes including the round shape of the nucleus, the absence of visible nucleoli and the presence of fine clumped chromatin. In large cell lymphoma and leukemia cells involvement of body fluid this concept becomes less challenging. Large cell lymphoma and leukemia cells tend to have large size nuclei, less mature chromatin, and visible nucleoli with and without cytoplasmic vacuoles. However, to reach accurate diagnosis and subclassification, the utilizing of flow cytometry, to confirm monoclonality, and other ancillary studies such immunocytochemistry, cytogenetics and molecular studies is needed. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Diagnostic Cytopathology of Serous Fluids.

Simple headache revealed a rare lymphoma: Waldenstrom macroglobulinemia with unique markers: a case report and review of the literature

BACKGROUND

Waldenstrom macroglobulinemia (WM) is a rare lymphoma with an incidence rate of 3 per million people per year, with approximately 1000 to 1500 new cases diagnosed each year in the USA. It is primarily seen in Caucasian males with a median age of 70 years old. Patients are most often asymptomatic, but WM can manifest itself with constitutional symptoms such as lethargy, bleeding, organomegaly, and neurological or fundoscopic abnormalities. WM is characterized by immunoglobulin M (IgM) monoclonal gammopathy, lymphocytic infiltration of bone marrow, and normocytic anemia due to bone marrow replacement.

CASE PRESENTATION

Our patient is a Hispanic 67-year-old female that presents with one month of intermittent band-like bilateral headache accompanied by dizziness, light-headedness, nausea, and blurred vision. A thorough diagnostic workup was performed, including serum protein electrophoresis (SPEP) with serum immunofixation (SIFE) showing an M spike and IgM kappa. Bone marrow biopsy was significant for lymphoplasmacytic infiltration with nodular B cells (CD19+, CD20+, CD22+). Computerized Tomography (CT) imaging showed splenomegaly in the patient. Treatment was provided for hyperviscosity syndrome with plasmapheresis twice. The patient reported improvement of her symptoms and was then scheduled for chemotherapy. Throughout 7 months, our patient received multiple cycles of bortezomib, dexamethasone, and rituximab. While her symptoms improved her psychiatric status got progressively worse.

CONCLUSION

It is important not to neglect symptoms such as a headache, which may seem small, but could serve as a clue in the diagnosis of Waldenstrom's macroglobulinemia.

MALT lymphoma of the colon: a clinicopathological review

Extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) occurs in approximately 9% of non-Hodgkin B cell lymphoma. However, it occurs only rarely within the colon. The presentation is often asymptomatic, and can have multiple endoscopic appearances, including a single or multinodular polypoid lesion. Furthermore, small biopsies can make histological evaluation challenging. The 2016 WHO classification update includes many molecular features of entities and expands the differential diagnosis of lymphoid lesions of the colon. In addition to immunohistochemistry, molecular methods may be tempting to use for small difficult cases. Furthermore, treatment approaches are varied for this entity, and not well studied. Therefore, an updated review on MALT lymphoma of the colon is needed.

MYD88 L265P mutation analysis is a useful diagnostic adjunct for lymphoplasmacytic lymphoma with pleural effusion

Lymphoplasmacytic lymphoma (LPL) is a marrow-based lymphoma, rarely involving extramedullary sites, particularly the pleural cavities. The distinction of lymphomatous pleural effusion (PE) in LPL patients from benign effusion is challenging. We conducted this study to examine whether MYD88 L265P mutation analysis is useful in distinguishing benign from lymphomatous PE in four patients with LPL, in which the initial marrow specimens were all positive for MYD88 mutation. In one case each with plasma cell- or lymphocyte-predominant PE, MYD88 mutation was positive, confirming lymphomatous effusion. The other lymphocyte-predominant PE was negative for MYD88 mutation, but was clonally related to a previous nodal biopsy and this PE was also considered to have LPL involvement. The fourth case developed large B-cell lymphoma in the PE 30 months later. The PE specimen was negative for MYD88 mutation but was clonally related to the diagnostic marrow tissue, indicating large cell transformation. Four cases of small lymphocyte-predominant benign PE from patients without history of lymphoma were examined and were all negative for MYD88 L265P mutation. In conclusion, in this small case series we showed that MYD88 L265P mutation analysis could serve as a useful adjunct in distinguishing benign from lymphomatous PE in patients with LPL.

Lung consolidation as a rare presentation of lymphoplasmacytic lymphoma with extramedullary Waldenström's macroglobulinemia

Objectives: Lymphoplasmacytic lymphoma (LPL) is a mature B cell lymphoma that usually involves the bone marrow, spleen and lymph nodes. Extramedullary involvement, including the lung, is rarely reported.

Case description: A 73-year-old female initially presented to our hospital complaining of productive cough of white-colour sputum for three weeks duration. She reported unintentional weight loss of ten pounds over the last five months. There was no history of haemoptysis, fever, night sweats, chills, recent infections or hospitalization. Chest imaging showed right lower lobe consolidation, small right pleural effusion. She was treated with oral antibiotic for pneumonia. After two months, a follow up chest imaging revealed persistent right lower lobe consolidation. Therefore, she was worked up for the possibility of malignancy. Bronchoscopy showed polypoid nodularities surrounded by black discoloured mucosa in the sub-segmental bronchi of the right lower lobe, and biopsy specimen revealed atypical B cell lymphocytic infiltrate. Polymerase chain reaction confirmed a clonal B-cell gene rearrangement supportive for a low-grade B-cell Lymphoma. Subsequently; serum immunofixation showed IgM of 1491 mg/dL (normal range 26–217 mg/dl) with normal levels of IgG and IgA. Urine contained free kappa light chains. Cytology with immunophenotyping of pleural fluid revealed lymphoplasmacytic lymphocytes. This combination of lab and bronchoscopy findings established the diagnosis of extramedullary Waldenström’s macroglobulinemia.

Conclusion: Waldenström’s macroglobulinemia, a manifestation of LPL, is associated with an IgM monoclonal gammopathy in the blood. Extramedullary involvement including the lung is rarely seen in LPL. Physicians need to be aware of this rare presentation.

High-grade Transformation of Low-grade B-cell Lymphoma: Pathology and Molecular Pathogenesis

Patients with low-grade (clinically indolent) lymphomas are at risk to undergo transformation to high-grade (clinically aggressive) lymphoma, although transformation only occurs in a subset of patients. When transformation occurs it is a critical event that determines the course of disease and is associated with unfavorable patient outcomes. Accurate detection of transformation, predictive biomarkers, and identification of specific molecular pathways implicated in the pathobiology of transformation will facilitate personalized therapeutic approaches and underpin advances in clinical outcomes. In this article, we present an update of the clinical and pathologic diagnostic criteria for low-grade B-cell lymphoma transformation and discuss the molecular alterations involved in the pathogenesis of this biological phenomenon.

Waldenström macroglobulinemia with extramedullary involvement at initial diagnosis portends a poorer prognosis

BACKGROUND

The prognostic importance of extramedullary involvement in patients with Waldenström macroglobulinemia (WM) at diagnosis and treatment options for these patients has not been well evaluated. In this study, we investigated the clinical manifestations, biological features, and effect of first-line therapy on the outcome of WM patients diagnosed with extramedullary involvement (EMWM) vs those with only bone marrow involvement (BMWM).

METHODS

We analyzed the clinical data of 312 WM patients diagnosed with EMWM (n = 106) and BMWM (n = 206) at The University of Texas MD Anderson Cancer Center from 1994 to 2014. EMWM was confirmed by biopsy, positron emission tomography-computed tomography, or magnetic resonance imaging, and clinical laboratory analyses.

RESULTS

Characteristics associated with EMWM were male sex (P = 0.027), age younger than 65 years (P = 0.048), presence of B symptoms (P < 0.001), high serum beta-2 macroglobulin (P < 0.001) level, low serum albumin level (P = 0.036), and cytogenetic abnormalities (P = 0.010). Kaplan-Meier survival analysis results showed that EMWM patients had a significantly shorter median overall survival (P < 0.001) and progression-free survival (PFS) (P < 0.001) than did BMWM patients. Chemotherapy combined with targeted therapy improved PFS for BMWM patients (P = 0.004) but not for EMWM patients. Additionally, initial treatment with rituximab significantly improved the PFS of BMWM patients (P = 0.012) but had no effect on EMWM patients. However, EMWM patients treated with nucleoside analogs attained a better PFS than those who did not (P = 0.021).

CONCLUSIONS

We show that extramedullary involvement at diagnosis is an adverse prognostic factor in WM patients and that first-line therapy with nucleoside analogs improved PFS for patients with EMWM. The study provides unique clinical and treatment observations in subtypes of WM patients.

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.

Extramedullary Waldenström macroglobulinemia

Disease assessment in Waldenstrom Macroglobulinemia (WM) is dependent on the percent involvement of B-cell neoplasm in the bone marrow and IgM paraprotein in the serum. A subset of patients also demonstrates extramedullary involvement, which is infrequently examined. The role of extramedullary involvement in the diagnosis and prognosis of WM is poorly understood. The purpose of this study is to report the characteristics of WM patients with extramedullary disease (EMD). Nine hundred and eight-five patients with WM were evaluated at one academic center and the presence of EMD was assessed in these patients. Forty-three (4.4%) patients were identified to have EMD. Nine (21%) patients presented with involvement at WM diagnosis, while 34 (79%) developed EMD post-therapy for WM. Most frequent EMD sites involved were pulmonary (30%), soft tissue (21%), cerebrospinal fluid (23%), renal (8%), and bone (9%). The median overall survival at 10 years was 79% (95% CI: 57-90%). This is the first study to describe the clinical characteristics, response and overall survival in patients with extramedullary WM. Further studies to define the molecular characteristics of this entity and mechanisms of its development are warranted.

Concurrent bladder lymphoma and bladder cancer presenting as metastatic bladder cancer

Malignant lymphoma of the bladder is a rare lesion, representing approximately 0.2% of the primary lesions and approximately 1.8% of the secondary lesions. A disseminated lymphoma presenting as a bladder mass is an infrequent phenomenon. The authors report the case of a 71-year-old patient with concurrent bladder lymphoma and bladder cancer presenting as metastatic bladder cancer. To the best of our knowledge, this is the first report of concurrent bladder lymphoma and bladder cancer.

Burkitt lymphoma arising from lymphoplasmacytic lymphoma following acquisition of MYC translocation and loss of the ETV6 tumor suppressor gene

Lymphoplasmacytic lymphoma is a mature B-cell lymphoma with variable plasmacytic differentiation that displays an indolent clinical course. Its transformation to a high-grade B-cell lymphoma may occur uncommonly. Although acquisition of a MYC translocation could result in transformation of a low-grade lymphoma into diffuse large B-cell lymphoma, Burkitt lymphoma, or B-lymphoblastic leukemia, to our knowledge the latter 2 transformations have not been well documented in lymphoplasmacytic lymphoma. We report the case of a 70-year-old woman with a 9-year history of lymphoplasmacytic lymphoma/Waldenström macroglobulinemia who presented with rapid enlargement of a left neck mass and pancytopenia, which was diagnosed as Burkitt lymphoma with extensive bone marrow involvement. A series of histopathologic, molecular, and cytogenetic evaluations proved a cytogenetic evolution including t(8;14)(q24;q32)/MYC-IgH and identical clonal B-cell gene rearrangements from the 2 distinct lymphomas, confirming stage 4 aggressive Burkitt lymphoma arising from lymphoplasmacytic lymphoma.

Waldenström macroglobulinemia: a review of the entity and its differential diagnosis

The definition of Waldenström macroglobulinemia (WM), originally described in 1944, has been refined substantially over time. The current fourth edition of the World Health Organization of lymphoid neoplasms, in large part, adopted criteria proposed for WM at a consensus conference in 2002. WM is defined as lymphoplasmacytic lymphoma involving the bone marrow associated with a serum immunoglobulin (Ig) M paraprotein of any concentration. Morphologically, WM is composed of a variable mixture of lymphocytes, plasmacytoid lymphocytes, and plasma cells. Immunophenotypically, the neoplastic cells express monotypic IgM and light chain: B lymphocytes express pan-B-cell antigens and surface Ig are usually negative for CD5 and CD10; and plasma cells are typically positive for CD138, CD38, CD45, cytoplasmic Ig, and CD19 (in a substantial subset of cases). The putative cell of origin of WM is a postantigen selected memory B-cell that has undergone somatic hypermutation. The most common cytogenetic abnormality in WM is del(6q), usually in the region 6q23-24.3, present in 40% to 50% of cases. IGH gene translocations are rare and recurrent chromosomal translocations or gene aberrations have not been identified in WM. Here, we provide a historical perspective of WM, review clinical and pathologic aspects of the disease as it is currently defined, and discuss some practical issues in the differential diagnosis of WM that pathologists encounter in the signout of cases.

t(14;18)(q32;q21)-bearing pleural MALT lymphoma with IgM paraproteinemia: value of detection of specific cytogenetic abnormalities in the differential diagnosis of MALT lymphoma and lymphoplasmacytic lymphoma

A 67-year-old woman presented with a pleural effusion and a tumor in the right pleural wall. Histological examination of thoracoscopic tumor and pleural biopsy specimens showed infiltration by medium sized cells, some of which showed plasmacytoid differentiation. In view of the presence of IgM paraproteinemia and bone marrow involvement by lymphoma cells, the patient was diagnosed tentatively as having lymphoplasmacytic lymphoma (LPL). However, chromosomal analysis of the cells in the pleural fluid detected t(14;18)(q32;q21), while fluorescence in situ hybridization was positive for 11% of the MALT1 split signal. Because of the presence of characteristic genetic abnormalities and notable extranodal involvement, the patient was diagnosed as having MALT lymphoma. She was treated with three courses of cladribine and rituximab, and achieved complete regression of the tumor. In this case the detection of t(14;18)(q32;q21) involving IGH and MALT1 was useful for the differential diagnosis of LPL and MALT lymphoma.

Diagnosis and Classification of Malignant Lymphoma and Related Entities in the Bone Marrow Trephine Biopsy

The trephine bone marrow (BM) biopsy is an important diagnostic tool in patients with malignant lymphoma. BM examination can serve to establish or confirm a primary diagnosis of lymphoma or to determine the extent of disease dissemination for staging purposes. BM histology renders information which cannot be gained equally from aspirate material, such as spacial distribution and extent of infiltrates, BM cellularity and fibrosis. Furthermore, cytology including flow cytometric immunophenotyping can give false-negative results in BM involvement by lymphoma due to intralesional fibrosis. In addition to morphological examination, the availability of a broad panel of antibodies suitable for paraffin-embedded tissues, in conjunction with less damaging decalcification procedures, nowadays enables us to perform complete immunophenotyping on BM trephines and allows for classification of lymphoma infiltrates according to established algorithms. Molecular determination of clonality and interphase fluorescent in situ hybridization can be employed selectively to resolve difficult cases. This review describes important diagnostic features of malignant lymphoma in the BM, relevant differential diagnoses, and the proper use of ancillary techniques.

Small Lymphoid Proliferations in Extranodal Locations

Context.—Low-grade non-Hodgkin lymphomas frequently involve extranodal sites including the gastrointestinal tract, skin, and lung, either selectively or as part of widespread dissemination. Differentiation from inflammatory or infectious conditions requires knowledge of specific histologic characteristics of the various entities as well as ancillary techniques.

Objective.—To describe the key features and provide diagnostic clues to the identification of specific extranodal low-grade lymphomas of T-cell and B-cell types including small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, extranodal marginal zone B-cell lymphomas of mucosal-associated lymphoid tissue, and hairy cell leukemia. Histologic and cytologic features are highlighted, as well as appropriate integration of results of ancillary diagnostic studies including flow cytometry, immunohistochemistry, molecular features, and cytogenetics.

Data Sources.—The published literature as well as personal experience from a specialized hematopathology practice at a large university medical center.

Conclusions.—Correct identification of extranodal low-grade lymphomas and differentiation from hyperplastic and inflammatory or infectious processes require the ability to distinguish each of the specific entities discussed. Ancillary studies are often indispensable in reaching a correct diagnosis.

Minimal change glomerulonephritis in chronic lymphocytic leukemia: pathophysiological and therapeutic aspects

BACKGROUND

So far, only 9 cases of minimal change glomerulonephritis (MCGN) related to chronic lymphocytic leukemia (CLL) have been described.

CASE REPORT

Our patient presented with severe nephrotic syndrome. Diagnostic biopsies confirmed MCGN and early-stage BCLL (Binet A). In contrast to previously described cases, kappa monoclonal IgM and cryoglobulins were also detected. The patient was treated with chlorambucil and prednisone. 3 weeks later, renal function and white blood cell (WBC) count were completely normal.

DISCUSSION

Although, in most cases, renal disease and CLL present separately, there is evidence for a causal relationship between the two disorders. Although it is widely approved that early-stage CLL should not be treated by medication, the severe nephrotic syndrome in our patient required immediate intervention. So far, there is no standard therapy for MCGN associated with CLL. Our combination therapy resulted in normalization of the nephrotic syndrome and the WBC count. Hence, we emphasize the importance of early recognition of renal symptoms in CLL and propose a successful therapy for nephrotic syndrome in MCGN associated with early-stage B-CLL. Additionally, the pathophysiological and therapeutic aspects of MCGN associated with CLL are retrospectively discussed.

Lymphoid neoplasms associated with concurrent t(14;18) and 8q24/c-MYC translocation generally have a poor prognosis

We identified 14 B-cell neoplasms with concurrent t(14;18) and chromosome 8q24 or c-MYC translocations shown by conventional cytogenetics or fluorescence in situ hybridization analysis. All cases assessed by conventional cytogenetics had a complex karyotype. There were 10 men and four women, with a median age of 55 years (range, 29-72). None of these patients had a history of follicular lymphoma. The biopsy specimens were obtained from bone marrow, lymph node, and extranodal sites. Morphologically, nine neoplasms had features of Burkitt or atypical Burkitt lymphoma/leukemia and three were diffuse large B-cell lymphoma with high-grade cytologic features. The remaining two cases were plasmablastic myeloma and low-grade B-cell lymphoma, respectively. All cases expressed BCL-2. The proliferation index assessed by using Ki-67 (MIB1) was 5% in the low-grade B-cell lymphoma, 80% in the plasmablastic myeloma, 90-95% in three cases of diffuse large B-cell lymphoma, and ranged from 90 to >99% in most Burkitt and atypical Burkitt neoplasms. The patient with low-grade B-cell lymphoma was treated with rituximab. All other patients received intensive combination chemotherapy. Two of these patients underwent bone marrow transplantation, and one patient received radiation therapy in addition to transplantation. The median follow-up period was 9 months (range, 3-81). In all, 10 patients died with a median survival of 9 months (range, 3-81). We conclude that most B-cell lymphomas with concurrent t(14;18) and 8q24/c-MYC translocations fall within the morphologic spectrum of diffuse large B-cell and Burkitt lymphoma. These neoplasms are high-grade and are associated with a poor prognosis. However, this combination of molecular abnormalities can also rarely occur in other neoplasms, such as the cases of low-grade B-cell lymphoma and plasmablastic myeloma in this study.

Lymphoplasmacytic lymphoma/waldenstrom macroglobulinemia: an evolving concept

The concept of Waldenstrom macroglobulinemia has evolved from the original description of a clinical syndrome to its more recent designation as a distinct clinicopathologic entity, that is, lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia (LPL/WM), in the World Health Organization (WHO) classification and by the participants of consensus meetings on WM. The diagnosis of LPL/WM, however, remains a challenge in daily practice. Distinguishing LPL/WM from other B-cell lymphomas, especially marginal zone B-cell lymphomas, which share overlapping morphologic features, is difficult. The traditional practice of separating LPL/WM from other lymphomas by an arbitrary level of serum IgM is no longer considered valid. The characteristic immunophenotype described for LPL/WM by the WHO classification, that is, CD5(-)CD10(-)CD23-, is observed in 60-80% of neoplasms, but variations from this pattern of antigen expression are common, with CD23 being detected in up to 40% of cases. Lack of a distinct molecular genetic hallmark complicates the distinction of LPL/WM from other B-cell lymphomas. Although the t(9;14) is stated to be present in 50% of cases in the WHO classification, translocations involving the Ig heavy chain including the t(9;14) are actually rare in LPL/WM. Deletion of 6q21-q23, a nonspecific finding, is the most common aberration reported in 40-70% of patients. At the molecular level, the neoplastic clone in most cases has undergone Ig variable gene mutation, but not isotype switching, and the clone retains the capability of plasmacytic differentiation. Currently, the diagnosis of LPL/WM can only be established by incorporating clinical and pathologic findings and excluding alternative diagnoses. In some cases, in our opinion, distinguishing LPL/WM from marginal zone B-cell lymphomas seems arbitrary using currently recommended criteria.

Diagnosis and management of Waldenstrom's macroglobulinemia

PURPOSE

To review the diagnostic criteria, prognostic factors, response criteria, and treatment options of patients with Waldenstrom's macroglobulinemia (WM).

METHODS

A review of published reports was facilitated by the use of a MEDLINE computer search and by manual search of the Index Medicus.

RESULTS

WM should be regarded as a distinct clinicopathologic entity and confined to those patients with lymphoplasmacytoid lymphoma who have demonstrable serum immunoglobulin M monoclonal protein. Treatment decisions should rely on specific clinical and laboratory criteria. Initiation of therapy should not be based on serum monoclonal protein levels per se. The three main choices for systemic primary treatment of symptomatic patients with WM include alkylating agents (chlorambucil), nucleoside analogs (fludarabine and cladribine), and the monoclonal antibody rituximab. There are no data from prospective randomized studies to recommend the use of one first-line agent over another, although consideration of a patient's candidacy for autologous stem-cell transplantation (ASCT) should be taken into account to avoid stem cell-damaging agents. There are preliminary data to suggest that combinations of nucleoside analogs and alkylating agents with or without rituximab may improve response rates at the expense of higher toxicity.

CONCLUSION

WM is a distinct low-grade lymphoproliferative disorder. When therapy is indicated, alkylating agents, nucleoside analogs, and rituximab are reasonable choices. Several factors, including the presence of cytopenias, need for rapid disease control, candidacy for ASCT, age, and comorbidities, should be taken into consideration when choosing the most appropriate primary treatment.

Clinicopathologic Features of Waldenström's Macroglobulinemia and Marginal Zone Lymphoma: Are They Distinct or the Same Entity?

Waldenstrom's macroglobulinemia (WM) is considered in the World Health Organization classification as a clinical syndrome associated with monoclonal immunoglobulin (Ig) M secretion, mainly observed in patients with lymphoplasmacytic lymphoma (LPL) and occasionally with other small B-cell lymphomas. Some authors consider it a rare distinct lymphoproliferative disorder with primary bone marrow infiltration and IgM monoclonal gammopathy. As LPL shares important morphologic and immunophenotypic overlaps with marginal zone B-cell lymphomas (MZLs) in cases showing plasmacytic maturation, it remains unclear if they constitute unique or distinct entities. Both diseases are composed of lymphocytes, lymphoplasmacytoid cells, and tumoral plasma cells with a surface (s) IgM-positive sIgD+/ cytoplasmic IgMpositive CD19+ CD20+ CD27+/ CD5 CD10 CD23 phenotype, without a specific marker. Extranodal mucosa-associated lymphoid tissue (MALT) lymphoma, nodal MZL (NMZL), and splenic MZL (SMZL) are distinct entities displaying common morphologic, immunophenotypic, and genetic characteristics. MALT lymphoma is clearly distinct from LPL, although bone marrow infiltration and IgM paraprotein are not rare. Splenic MZL and NMZL are incompletely characterized, but a plasmacytoid/plasmacytic differentiation, autoimmune manifestations, and monoclonal component are frequent in both diseases. Bone marrow involvement is constant in SMZL and present in 60% of NMZLs. Molecular IgVH gene analysis has confirmed this heterogeneity, particularly within SMZL, with mutated and unmutated cases. Further studies are needed to clarify the pathogenesis of these MZLs and their relationship with LPL.