Biomedical subjects

Pei Lin

Publications and source records attributed to Pei Lin.

At least 19 recordsLinked to original sources

PubMed2006

Sequence analysis proves clonal identity in five patients with typical and blastoid mantle cell lymphoma.

Mantle cell lymphoma (MCL) is typically composed of small irregular lymphoid cells. Blastoid variants, composed of lymphoblast-like (classic type) or large (pleomorphic type) cells, arise de novo or in patients with typical MCL. Although it has been assumed that blastoid variant represents histologic transformation of typical MCL, the clonal relationship between the two tumors has rarely been assessed at the molecular level. We identified five patients with typical MCL who subsequently developed the blastoid variant. There were two men and three women with a median age of 65 years (range, 34-70) at diagnosis of typical MCL involving lymph nodes. The median interval between typical and blastoid MCL was 36 months (range, 11-103). Subsequent blastoid variant MCL involved soft tissue (two), lymph node (one), ileum (one), or rectum (one). All typical and blastoid neoplasms were positive for CD20, cyclin D1, and monotypic surface immunoglobulin light chain, and all typical cases were positive for CD5. Two blastoid neoplasms lost CD5 expression, one of which aberrantly expressed CD10. Immunostaining for Ki-67 showed a median proliferative fraction of 20% in typical and 70% in blastoid neoplasms. Sequence analysis of the VDJ regions of the rearranged IgH allele proved clonal identity in each set of paired samples in all five patients. These results support the concept that blastoid MCL arising in patients with typical MCL represents histologic transformation of the original neoplastic clone.

Adult↗

PubMed2006

Nuclear BCL-10 expression is common in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia and does not correlate with p65 NF-kappaB activation.

B-cell lymphoma 10 (BCL-10) is expressed in the cytoplasm of normal germinal center and marginal zone B-cells and is involved in lymphocyte development and activation. Aberrant nuclear expression of BCL-10 occurs in a subset of extranodal marginal zone B-cell lymphomas (MALT lymphomas), primarily those with the t(1;14)(p22;q32) or t(11;18)(q21;q21). Little is known about BCL-10 expression in lymphoplasmacytic lymphoma/Waldenström macroglobulinemia (LPL/WM). We assessed for BCL-10 in 51 bone marrow (BM) specimens involved by LPL/WM using immunohistochemical methods. All patients had monoclonal IgM in serum. Extent of BM involvement was assessed using PAX-5/BSAP and CD20 immunostains and the pattern and percentage of B-cells positive for BCL-10 was determined. The p65 subunit of nuclear factor-kappa B (NF-kappaB), a molecule downstream of BCL-10, was also assessed immunohistochemically. Nuclear BCL-10 staining was present in 28/51 (55%) specimens. BCL-10 expression correlated with greater extent of BM involvement (P=0.001), but did not correlate with serum IgM paraprotein levels, type of immunoglobulin light chain, or clinical variables. Nuclear expression of the p65 subunit of NF-kappaB was detected in 17/50 (34%) specimens, suggesting that NF-kappaB is active in a subset of LPL/WM. p65 NF-kappaB activation did not correlate with nuclear BCL-10 immunostaining. Cytogenetic analysis in 29 cases showed no evidence of the t(1;14) or t(11;18). These results indicate that nuclear BCL-10 expression is common in LPL/WM and does not correlate with MALT lymphoma-associated translocations or p65 NF-kappaB nuclear staining.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Translocation (3;8)(q26;q24): a recurrent chromosomal abnormality in myelodysplastic syndrome and acute myeloid leukemia.

We identified a reciprocal translocation between chromosomes 3 and 8, with breakpoints at bands 3q26 and 8q24, in five patients with myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML). The t(3;8)(q26;q24) was the sole cytogenetic aberration in two patients, was associated with trisomy 13 in one patient, and occurred with monosomy 7 in two patients. In three patients, the AML or MDS developed 36, 52, and 57 months following chemotherapy for soft tissue sarcoma, mantle cell lymphoma, and diffuse large B-cell lymphoma, respectively; in these three patients, the neoplasms were considered to be therapy-related. All five patients displayed marked trilineage dysplasia and variable degrees of cytopenias, with marked thrombocytosis noted in one patient and a normal platelet count in another patient. All patients were treated with combination chemotherapy; at writing, four were still alive and one had died during a follow-up period ranging from 1 to 16 months. We conclude that the t(3;8)(q26;q24) is a recurrent translocation associated with therapy-related MDS/AML or de novo AML, and is frequently associated with monosomy 7.

Acute Disease↗

PubMed2006

Primary plasma cell leukemia: morphologic, immunophenotypic, and cytogenetic features of 4 cases treated with chemotherapy and stem cell transplantation.

Plasma cell leukemia (PCL) is a neoplastic disorder of plasma cells of which there are 2 forms, primary PCL and secondary PCL, the latter occurring in patients with a history of plasma cell myeloma. We describe 4 patients with primary PCL. In all cases, the bone marrow aspirate smears and biopsy specimens demonstrated a diffuse infiltrate of atypical plasma cells that were difficult to classify using morphologic criteria alone. Immunophenotypic studies showed that each case was positive for plasma cell-associated antigens (cytoplasmic immunoglobin, CD38, or CD138) and negative for CD20. Of 4 cases, 3 had complex karyotypes, including the t(11;14)(q13;q32) or del(11)(q13). Despite chemotherapy and the use of novel therapeutic agents and stem cell transplantation, all 4 patients had short survival.

ADP-ribosyl Cyclase 1↗

PubMed2006

Targeting beta2-microglobulin for induction of tumor apoptosis in human hematological malignancies.

We discovered that monoclonal antibodies (mAbs) specific to human beta(2)-microglobulin (beta(2)M) induce apoptosis in vitro and were therapeutic in mouse models of myeloma and other hematological tumor cells. Cell death occurred rapidly, without the need for exogenous immunological effector mechanisms. The mAbs induced cell death via recruiting MHC class I molecules to lipid rafts and activating Lyn and PLCgamma2, leading to activated JNK and inhibited PI3K/Akt and ERK, compromised mitochondrial integrity, and caspase-9-dependent cascade activation. Although the expression of beta(2)M on normal hematopoietic cells is a potential safety concern, the mAbs were selective to tumor-transformed cells and did not induce apoptosis of normal cells. Therefore, such mAbs offer the potential for a therapeutic approach to hematological malignancies.

Animals↗

PubMed2006

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.

Adult↗

PubMed2006

Acute myeloid leukemia associated with variant t(8;21) detected by conventional cytogenetic and molecular studies: a report of four cases and review of the literature.

Acute myeloid leukemia (AML) with the t(8;21) (q22;q22) creating the AML1-ETO fusion gene is a distinct type of AML generally associated with a favorable prognosis. The clinicopathologic features of AML carrying variant t(8;21) are less well characterized. We report 4 cases of AML characterized by ins(8;21)(q22;q22q22), t(1;21;8)(q25;q22;q22), t(8;11;21)(q22;q13;q22), and t(4;21;8;12)(q31.3;q22;q22;q15), respectively. Fluorescence in situ hybridization or reverse transcriptase-polymerase chain reaction assay confirmed the presence of AML1-ETO or its transcripts in 3 cases assessed. Each neoplasm had morphologic characteristics of AML associated with the t(8;21). The blasts in 2 cases expressed CD19. All patients were treated with combination chemotherapy and are in complete remission, despite 2 relapses in 1 patient, with a follow-up period ranging from 8 to 46 months. We conclude that cases of AML with variant t(8;21) display morphologic, immunophenotypic, and clinical features similar to classical cases. A combination of conventional cytogenetic, and molecular analyses allows identification of these variants.

Adolescent↗

PubMed2006

Activating FLT3 mutations are detectable in chronic and blast phase of chronic myeloproliferative disorders other than chronic myeloid leukemia.

FLT3 gene mutations, either internal tandem duplication (ITD) or D835 point mutations, have been studied extensively in acute myeloid leukemia and myelodysplastic syndrome (MDS). Little is known about FLT3 mutations in chronic myeloproliferative diseases (CMPDs) or their relationship with V617F JAK2 mutations. We analyzed bone marrow samples from 142 patients with Philadelphia (Ph) chromosome- CMPD or CMPD/MDS and from 119 patients with Ph+ chronic myeloid leukemia (CML) using a multiplex polymerase chain reaction assay. FLT3 mutations, 11 ITD and 2 D835, were detected in 13 (9.2%) patients with CMPD or CMPD/MDS, 7 in blast phase and 6 in chronic phase. Analyses for JAK2 mutations in 11 of 13 cases were all negative. By contrast, no FLT3 mutations were detected in CML, including 108 chronic and 11 blast phase cases. FLT3 mutations occur in approximately 10% of CMPD and CMPD/MDS but are not observed in JAK2+ CMPD or in CML.

Blast Crisis↗

PubMed2006

Expression of B cell-specific activator protein/PAX5 in acute myeloid leukemia with t(8;21)(q22;q22).

The blasts of acute myeloid leukemia (AML) with t(8;21)(q22;q22) frequently express the B-cell antigen CD19, which is regulated by B cell-specific activator protein (BSAP) encoded by the PAX5 gene, a protein important for B-cell lineage commitment and development. We assessed for BSAP expression in 28 AML cases with t(8;21) and 46 AML cases of other types. CD19 was expressed by 26 (93%) cases of AML with t(8;21) and 1 AML case (2%) without t(8;21). We also tested a subset of cases for the B-cell transcription factors Oct2 and OCA-B (BOB.1) and the B-cell antigens CD20, CD22, and CD79a. Immunostaining performed on bone marrow biopsy specimens demonstrated BSAP expression in all 28 AML cases with t(8;21): weak, 21; strong, 7. By contrast, BSAP was expressed weakly in only 1 AML case without t(8;21). Oct2 was expressed strongly in 12 of 16 AML cases with t(8;21) and 19 of 46 without t(8;21). OCA-B, CD20, CD22, or CD79a were negative in all cases assessed. These results indicate that silencing of PAX5 is not required for commitment to myeloid differentiation and that BSAP expression in AML is found mainly in cases with t(8;21).

Acute Disease↗

PubMed2006

Myeloid sarcoma of the urinary bladder and epididymis as a primary manifestation of acute myeloid leukemia with inv(16).

Myeloid sarcoma (MS) of the lower urinary tract is rare. We describe a 47-year-old man with hematuria, who was subsequently found to have MS involving bladder and epididymis. The neoplasm was composed predominantly of blasts that expressed CD68, CD117, myeloperoxidase, and lysozyme, with occasional immature eosinophils. Although blood and bone marrow examinations showed no morphologic evidence of leukemia, conventional cytogenetic studies of marrow demonstrated inv(16)(p13q22) in 4 of 20 metaphases; fluorescence in situ hybridization of the bladder neoplasm also showed inv(16). Following chemotherapy, the patient has been in complete remission for 32 months. In our literature review, we identified 7 cases of MS involving bladder, only 3 without evidence of an associated myeloid neoplasm in marrow, none with cytogenetic data. A high index of suspicion is required to establish the diagnosis of MS involving bladder. Cytogenetic analysis is useful for both demonstrating minimal marrow disease and classifying MS in paraffin-embedded tissue sections.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2006

Chronic myeloproliferative diseases with the t(5;12)(q33;p13): clonal evolution is associated with blast crisis.

Chronic myeloproliferative diseases (CMPDs) associated with t(5;12)(q33;p13) are reported to be responsive to imatinib mesylate. We studied 5 cases of CMPD with isolated t(5;12) treated at our hospital between January 1993 and October 2004. All were men with a median age of 55 years (range, 18-68 years). In the peripheral blood, each had marked leukocytosis, with variable eosinophilia (n = 4), monocytosis (n = 3), or basophilia (n = 2). Bone marrow specimens were hypercellular (70%-100%) with marked myeloid hyperplasia in each patient, but only 1 patient had eosinophilia, monocytosis, and basophilia. Follow-up ranged from 23 to 182 months (median, 48 months). Four died 23 to 182 months after initial diagnosis, 3 of blast crisis and 1 of cardiac complications of severe eosinophilia. Additional cytogenetic aberrations were identified at the time of blast crisis. Of 3 patients treated with imatinib, 2 responded, but only 1 had a sustained response. CMPD with t(5;12) commonly transforms to blast phase, and transformation is associated with cytogenetic evidence of clonal evolution.

Adolescent↗

PubMed2005

Targeting heat shock proteins for immunotherapy in multiple myeloma: generation of myeloma-specific CTLs using dendritic cells pulsed with tumor-derived gp96.

PURPOSE: To develop effective immunotherapies for patients with multiple myeloma, it is important to use novel tumor antigens. Recent studies in solid tumors show that tumor-derived heat shock proteins (Hsp) can be used as immunogen; however, no such study has yet been reported in multiple myeloma. EXPERIMENTAL DESIGN: We examined whether myeloma-derived Hsp gp96 can be used as a myeloma antigen. Specific CTL lines were obtained after repeatedly stimulating T cells with autologous, HLA-A*0201+ dendritic cells pulsed with gp96 derived from HLA-A*0201+ human myeloma cell line (HMCL) U266 or primary myeloma cells. RESULTS: These T cells lysed not only gp96-pulsed dendritic cells, U266, and other HLA-A*0201+ HMCLs IM-9 and XG1 but also effectively killed HLA-A*0201+ primary myeloma cells from patients. No killing was observed against unpulsed dendritic cells, dendritic cells pulsed with control gp96, HLA-A*0201- HMCLs, and primary myeloma cells, or HLA-A*0201+ nonmyeloma cells. Cytotoxicity was mainly MHC class I/HLA-A*0201 restricted, suggesting that the CTLs recognized gp96-chaperoned peptides on HLA-A*0201 that were derived from shared myeloma antigens and that myeloma cells naturally present these peptides in the context of their surface MHC molecules. Upon antigen stimulation, these T cells secreted IFN-gamma and tumor necrosis factor-alpha, indicating that they belong to type 1 T-cell subsets. CONCLUSION: These results show that these T cells are potent CTLs that are able to effectively lyse myeloma cells but not normal blood cells and also suggest that Hsps from allogeneic tumor cells may be used as vaccines to immunize patients.

Antigens, Neoplasm↗

PubMed2005

The utility of interphase fluorescence in situ hybridization for the detection of the translocation t(11;14)(q13;q32) in the diagnosis of mantle cell lymphoma on fine-needle aspiration specimens.

BACKGROUND: Mantle cell lymphoma can be difficult to differentiate cytologically from other small cell non-Hodgkin lymphomas. Nevertheless, the distinction is important, because mantle cell lymphoma is more aggressive than other small cell non-Hodgkin lymphomas. The purpose of this study was to determine whether fluorescence in situ hybridization (FISH) is helpful in diagnosing mantle cell lymphoma on fine-needle aspiration (FNA) specimens by detecting the t(11;14)(q13;q32) translocation that is characteristic of this tumor. METHODS: Fifty-five lymph node FNA specimens from 53 patients were analyzed using FISH. A 2-color FISH assay that employed probes at the 14q32 (immunoglobulin H) and 11q13 (dual-colored, directly labeled cyclin D1) loci was used. The number of single-fusion and double-fusion signals in 200 cells was counted. If > or = 14% single-fusion signals or > or = 1.5% double-fusion signals or both were present, then the sample was considered FISH positive. The findings were correlated with the cytologic, histologic, and immunophenotypic findings in each specimen. RESULTS: Of the 55 cytology specimens, 17 were mantle cell lymphomas, and 38 were nonmantle cell lymphomas, including 16 small lymphocytic lymphomas (9 of 16 in an accelerated phase), 5 large cell lymphomas, 5 follicular lymphomas, 7 transformed large cell lymphomas (Richter syndrome), 3 atypical lymphoid proliferations, and 2 low-grade B-cell lymphomas. All 17 mantle cell lymphomas were positive by FISH. In addition, there were six small lymphocytic lymphomas (two in accelerated phase), one transformed large cell lymphoma, and one large cell lymphoma of follicular origin positive by FISH. The mean number of single-fusion and double-fusion signals, respectively, was 36 and 33 in mantle cell lymphoma specimens and 19 and 3 in positive nonmantle cell lymphoma specimens. CONCLUSIONS: The detection of the t(11;14)(q13;q32) translocation by FISH analysis was helpful in diagnosing mantle cell lymphoma on FNA specimens. Double-fusion signals were more specific for mantle cell lymphoma than single-fusion signals. In rare instances, other non-Hodgkin lymphomas also showed increased numbers of single-fusion signals that were not necessarily indicative of the t(11;14)(q13;q32) translocation. Therefore, in an initial diagnosis of mantle cell lymphoma, significant numbers of double-fusion FISH signals should be identified and interpreted in conjunction with the cytologic and immunologic studies.

Biopsy, Fine-Needle↗

PubMed2005

A role for PML3 in centrosome duplication and genome stability.

The promyelocytic leukemia gene (PML), which is disrupted by the chromosomal translocation t(15;17) in acute promyelocytic leukemia (APL), encodes a multifunctional protein involved in several important cellular functions. Herein, we demonstrate that PML is localized to centrosomes and that PML deficiency leads to centrosome amplification. By using PML isoform-specific antibodies, we found PML3-specific association with the centrosome and the pole of the mitotic spindle. PML3 deficiency leads to dysregulation of the centrosome duplication checkpoint. Furthermore, PML3 physically interacts with Aurora A and regulates its kinase activity. Specific knockdown of PML3 activates Cdk2/cyclin kinase activity. The results of this study implicate a direct role for PML3 in the control of centrosome duplication through suppression of Aurora A activation to prevent centrosome reduplication.

Aurora Kinases↗

PubMed2005

NY-ESO-1 is highly expressed in poor-prognosis multiple myeloma and induces spontaneous humoral and cellular immune responses.

The presence of a metaphase cytogenetic abnormality (CA) is the key negative predictor of outcome in patients with multiple myeloma (MM). Gene expression profiling (GEP) of such patients showed increased expression of NY-ESO-1 compared to patients with normal cytogenetics (60% versus 31%; P = .004). NY-ESO-1 was also highly expressed in relapsing MM especially patients with CA (100% versus 60.7%; P < .001). GEP findings were confirmed at the protein level by immunostaining of marrow biopsies for NY-ESO-1. We detected spontaneous NY-ESO-1-specific antibodies by enzyme-linked immunosorbent assay in 33% of patients with NY-ESO-1+ MM, especially in CA patients (9 of 13; 70%), but in none of the NY-ESO-1- patients with MM (n = 27) or healthy donors (n = 21). Spontaneous NY-ESO-1(157-165)-specific T cells (0.2%-0.6% of CD8+ T cells) were found in the peripheral blood of NY-ESO-1+ MM with HLA-A*0201/NY-ESO-1(157-165) tetramers. These NY-ESO-1-specific T cells, when expanded, killed primary MM cells (50% lysis, effector-target [E/T] ratio, 10:1). Our data demonstrate that NY-ESO-1 is frequently expressed in MM with CA and is capable of eliciting spontaneous humoral and T-cell immunity. The pool of NY-ESO-1-specific cytotoxic T cells expands easily on NY-ESO-1 peptide stimulation and is functionally active. NY-ESO-1 should therefore be an ideal tumor target antigen for immunotherapy of patients with poor-prognosis MM.

Antibodies↗

PubMed2005

Extranodal lymphomas of the head and neck.

Malignant lymphomas represent approximately 5% of all malignant neoplasms of the head and neck and may involve nodal or extranodal sites. Nodal head and neck lymphomas are similar to other nodal sites and are not further reviewed here. The head and neck region is the second most frequent anatomical site of extranodal lymphomas (after the gastrointestinal tract). Most are non-Hodgkin's lymphomas of B-cell lineage, and overall diffuse large B-cell lymphoma is the most common type. Hodgkin's lymphoma rarely occurs in extranodal sites. Other hematologic neoplasms that commonly involve extranodal sites of the head and neck are also discussed. In this review, we begin by discussing lymphomas involving the head and neck according to anatomical site. Then we discuss specifically the pathological findings of extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue, plasmablastic lymphoma, extramedullary plasmacytoma, and extranodal natural killer/T-cell lymphoma of nasal type.

Head and Neck Neoplasms↗

PubMed2005

Expression of heat-shock protein-90 in non-Hodgkin's lymphomas.

Heat-shock protein-90 (HSP90) inhibitors are currently being used in phase I clinical trials for treating patients with a variety of neoplasms including lymphomas. Using immunohistochemical methods, we assessed for HSP90 expression in 412 cases of non-Hodgkin's lymphoma. In B-cell lymphomas, HSP90 was moderately to strongly expressed in all cases of Burkitt's lymphoma (5/5, 100%), and in subsets of follicular lymphoma (17/28, 61%), diffuse large B-cell lymphoma (27/46, 59%), nodal marginal zone B-cell lymphoma (6/16, 38%), plasma cell neoplasms (14/39, 36%), small lymphocytic lymphoma/chronic lymphocytic leukemia (3/9, 33%), mantle cell lymphoma (12/38, 32%) and lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia (3/10, 30%). HSP90 was weakly expressed in six of 14 (43%) cases of extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue. In T-cell lymphomas, HSP90 was moderately to strongly expressed in subsets of anaplastic large-cell lymphoma (14/24, 58%; 9/12 ALK+ and 5/12 ALK-), precursor-T-cell lymphoblastic leukemia/lymphoma (20/65, 31%), unspecified peripheral T-cell lymphoma (8/43, 23%) and angioimmunoblastic T-cell lymphoma (2/17, 12%). HSP90 was weakly expressed in seven of 58 (12%) cases of mycosis fungoides. We conclude that HSP90 is commonly expressed in a subset of many types of B- and T-cell lymphoma. These data suggest that many lymphoma types are suitable targets for modulation of HSP90 activity, and that HSP90 inhibitors are a potential investigational therapy for lymphoma patients.

Cell Line, Tumor↗

PubMed2005

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.

Antigens, CD↗