Molecular analysis of mucosa-associated lymphoid tissue (MALT) lymphoma of ocular adnexa.

Lymphomas of mucosa-associated lymphoid tissue (MALT) are a distinct subgroup of extranodal B-cell non-Hodgkin's lymphomas. Most studies have failed to demonstrate the clonal rearrangement of BCL-1, BCL-2 or c-MYC genes for MALT lymphomas. Further, alteration of the p53 gene is rarely demonstrated in low-grade MALT lymphomas, but can be detected in high-grade disease. Lymphomas of the ocular adnexa represent approximately eight percent of all extranodal lymphomas, most of which are MALT lymphomas, but few studies had explored the alterations of BCL-1, BCL-2, c-MYC and p53 genes specifically for ocular MALT lymphomas. We investigated the changes to BCL-1, BCL-2, c-MYC and p53 genes in these lymphomas for Taiwanese patients. Clonal rearrangement for immunoglobulin heavy-chain (IgH), BCL-1, BCL-2, c-MYC and p53 genes was examined for 16 cases of ocular MALT lymphoma. Restriction-length polymorphism and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) of the DNA, corresponding to exons 5 through 9, followed by DNA sequencing, were utilized to analyze the possible mutations of the p53 gene for these tumors. Thirteen of the cases revealed rearranged IgH genes using Southern blotting or PCR. No rearrangement of BCL-1, BCL-2, c-MYC or p53 genes was discovered, with point mutation of the p53 gene in one case. As for other types of MALT lymphomas, BCL-1, BCL-2 and c-MYC genes are not implicated in the pathogenesis of the ocular sub-group. Although alteration of the p53 gene is rare for low-grade ocular MALT lymphoma, its role in disease progression merits further research.     

Gain-of-function mutations and copy number increases of Notch2 in diffuse large B-cell lymphoma

Signaling through the Notch1 receptor has a pivotal role in early thymocyte development. Gain of Notch1 function results in the development of T-cell acute lymphoblastic leukemia in a number of mouse experimental models, and activating Notch1 mutations deregulate Notch1 signaling in the majority of human T-cell acute lymphoblastic leukemias. Notch2 , another member of the Notch gene family, is preferentially expressed in mature B cells and is essential for marginal zone B-cell generation. Here, we report that 5 of 63 (~8%) diffuse large B-cell lymphomas, a subtype of mature B-cell lymphomas, have Notch2 mutations. These mutations lead to partial or complete deletion of the proline-, glutamic acid-, serine- and threonine-rich (PEST) domain, or a single amino acid substitution at the C-terminus of Notch2 protein. Furthermore, high-density oligonucleotide microarray analysis revealed that some diffuse large B-cell lymphoma cases also have increased copies of the mutated Notch2 allele. In the Notch activation-sensitive luciferase reporter assay in vitro , mutant Notch2 receptors show increased activity compared with wild-type Notch2. These findings implicate Notch2 gain-of-function mutations in the pathogenesis of a subset of B-cell lymphomas, and suggest broader roles for Notch gene mutations in human cancers. ( Cancer Sci 2009; 100: 920–926)     

BCL-6 and other genomic alterations in non-Hodgkin's lymphoma (NHL).

This study reports on the frequency and disease association pattern of a number of gene rearrangements in a large panel of lymphoid tumours (n = 94). We detected the t(11;14) translocation, involving rearrangement of the BCL-1 locus, in 60% of mantle cell lymphomas. The BCL-2 gene, located at band 18q21, was rearranged in 42% of follicle centre lymphomas (FCL) and in 15% of diffuse large B-cell (DLBC) lymphomas. In this study, 80% of the c-MYC rearrangements were detected in aggressive diffuse lymphoma subsets but, interestingly, 9% of FCL showed involvement of t(8q24) translocation. In our study, rearrangements of the BCL-6 gene at band 3q27 were found in 31% of DLBC lymphomas. Interestingly, 50% of the BCL-6 rearrangement positive lymphoma cases had coexisting gene rearrangements involving all of the aforementioned gene loci. The molecular dissection of these genes will improve our understanding of the genesis of the diverse clinicopathological subtypes.     

Recurrent deletions of the TNFSF7 and TNFSF9 genes in 19p13.3 in diffuse large B-cell and Burkitt lymphomas

A single nucleotide polymorphism-chip analysis of 98 cases of aggressive B-cell lymphomas revealed a recurrent deletion at 19p13 in nine of the cases. Six further cases with deletions encompassing this region were found in array-comparative genomic hybridization data of 295 aggressive B-cell lymphomas from a previous study. Three cases even showed a homozygous deletion, suggesting a tumor suppressor gene in the deleted region. Two genes encoding members of the tumor necrosis factor superfamily (TNFSF) were located in the minimally deleted region, that is, TNFSF7 and TNFSF9. As no mutations were found within the coding exons of the remaining alleles in the lymphomas with heterozygous deletions, we speculate that the deletions may mostly function through a haploinsufficiency mechanism. The cases with deletions encompassed both diffuse large B-cell lymphomas and Burkitt lymphomas, and a deletion was also found in a Hodgkin lymphoma cell line. Thus, TNFSF7 and TNFSF9 deletions are recurrent genetic lesions in multiple types of human lymphomas.     

Mutation analysis of mitotic checkpoint genes (hBUB1 and hBUBR1) and microsatellite instability in adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a neoplasm of T-lymphocytes, and human T-cell lymphotropic virus type-I (HTLV-I) is etiologically considered as the causative virus of ATLL. The karyotypes of ATLL are very complex in both number and structure, although no specific karyotype abnormalities have been identified. HTLV-I is thought to integrate its provirus into random sites in host chromosomal DNA and induces chromosomal instability. The BUB gene is a component of the mitotic checkpoint in budding yeast. Recently, human homologues of the BUB were identified and mutant alleles of hBUB1 and hBUBR1 were detected in two colorectal tumor cell lines, which showed microsatellite instability (MIN). In vitro, BUB proteins form a complex of monomers. These proteins interact with the human MAD1 gene product, a target of the HTLV-1 tax oncogene. We examined the role of checkpoint gene in the chromosomal abnormalities of ATLL by investigating mutations of hBUB1 and hBUBR1, and MIN of replication errors of BAX, insulin-like growth factor, and transforming growth factor beta type II. We analyzed ten cases with ATLL and eight B-cell lymphomas (five diffuse large cell lymphomas, three follicular lymphomas). Complex chromosomal abnormalities were detected in ATLL, while B-cell lymphomas showed only simple or minimal chromosomal abnormalities. Significant mutations/deletion of hBUB1 or hBUBR1 were detected in four of ten cases with ATLL, including two heterozygous point mutations, one homozygous point mutation, and one with a 47 bp deletion. In contrast, only one of eight B-cell lymphomas showed nonsense mutation of hBUBR1. None of the ATLL and B-cell lymphomas showed MIN. In the multistage process of leukemogenesis of ATLL, our findings indicate that mutations of mitotic checkpoint genes may play an important role in the induction of complex chromosomal abnormalities.     

Monoclonal Antibody against PRADl/Cyclin Dl Stains Nuclei of Tumor Cells with Translocation or Amplification at BCL-1 Locus

Mouse monoclonal antibodies were produced against the bacterial product encoded by human PRAD1/ cyclin Dl gene, which is known to be involved in tumors with translocation or amplification at BCL-1 locus of 11ql3. The immunizing antigens used were GST-PRAD1 and T7 gene 10-PRAD1 fusion products. Four antibodies were reactive with both PRAD1 fusion products and cell lysates of B-cell tumor cell lines with t(ll;14)(ql3;q32) and a breast cancer cell line with 11ql3 amplification, on immunoblotting. An immunofluorescence study showed that only one of them stained nuclei of cells with 11q13 abnormalities. Since this antibody proved applicable for conventional paraffin-embedded tissue sections, immunohistologic staining of various lymphoma tissues was performed. Eight of 11 mantle cell lymphomas showed intermediate to strong positivity and 6 of the positive cases demonstrated characteristic staining patterns that were either predominantly nuclear or both nuclear and cytoplasmic. The nuclear staining pattern was not observed with other types of lymphoma and thus may correlate with PRAD1 mRNA overexpression.     

Genetic abnormalities in marginal zone B-cell lymphoma

Marginal zone B-cell lymphoma (MZBCL) including extranodal mucosa-associated lymphoid tissue (MALT)-type lymphoma, nodal, and splenic MZBCL represents a distinct subtype of B-non-Hodgkin's lymphoma. Recently, important progress in the elucidation of the genetic mechanisms underlying the pathogenesis and disease progression of these lymphomas has been made. The API2 gene, an inhibitor of apoptosis, and the novel MLT gene have been found to be altered by the t(11;18)(q21;21), which represents the most frequent structural chromosomal abnormality in extranodal low-grade MALT lymphoma. Another gene involved in the regulation of apoptosis, the BCL10 gene, has been cloned from a MALT lymphoma cytogenetically characterized by the t(1;14)(p22;q32). Along the same lines, inactivating mutations of the proapoptotic FAS gene have been detected in a relatively high proportion of extranodal MZBCLs. Considering these data and the fact that at least some MALT lymphomas show low levels of apoptosis and seem to escape from FAS-mediated apoptosis one may speculate that abrogation of apoptosis constitutes a central pathogenetic mechanism in the development of these lymphomas. The pathogenetic role of trisomy 3, the most frequent numerical chromosomal change of MZBCL, is not known. The minimal overrepresented region has been delineated to 3q21-23 and 3q25-29 using comparative genomic hybridization. The BCL6 proto-oncogene, located on 3q27, which is rearranged in some MZBCL and a high proportion of large cell B-cell lymphomas with extranodal localization, represents one of the candidate genes residing in these critical regions.     

Follicle center lymphoma is associated with significantly elevated levels of BCL-6 expression among lymphoma subtypes, independent of chromosome 3q27 rearrangements.

The BCL-6 gene, located on chromosome 3q27, is implicated in the normal germinal center formation and is frequently rearranged in a wide spectrum of lymphomas. However the links between genetic alterations and expression of the gene are not clearly determined. We established a quantitative RT-PCR assay based on TaqMan technology to quantify BCL-6 mRNA expression in different subtypes of lymphomas and to compare the level of expression in lymphomas characterized by the presence or absence of BCL-6 translocation. Total RNA was extracted from 105 nodes biopsies (35 diffuse large B cell lymphomas (DLBCL); 26 follicle center lymphomas (FCL); 7 marginal zone lymphomas (MZL); 6 mantle cell lymphomas (MCL); 6 chronic lymphocytic leukemia (CLL); 5 T cell lymphomas (TCL); 7 classical Hodgkin diseases (HD); 6 nodal metastasis (NM); and 7 reactive hyperplasia (RH)). BCL-6 gene rearrangement was assessed by Southern blot analysis in 75% of 3q27(+) DLBCL (n = 20) cases and 67% of 3q27(+) cases (n = 10). The highest level of relative BCL-6 expression was observed in FCL (9.12 +/- 7.28) comparatively to the other lymphoma subtypes including DLBCL (2.53 +/- 1.82; P < 0.001), MCL (1.23 +/- 0.73), MZL (1.49 +/- 1.3), HD (1.60 +/- 1.00), TCL (1.75 +/- 1.64), but also RH (3.91 +/- 3.12) or NM (1.95 +/- 2.6). Among the 26 FCL cases, we observed a lower expression in grade 3 (n = 8) than in grade 1/2 (P < 0.001). Conversely, we failed to show any difference between 3q27(+) DLBCL and 3q27(-)DLBCL cases (P = 0.42). Paradoxically BCL-6 expression in 3q27(+) FCL (n = 10) was significantly lower than in 3q27(-) FCL cases (P = 0.035). Finally, this study showed that BCL-6 expression in lymphoma is largely independent of chromosome 3q27 rearrangement and is more related to the histological subtype. Clinical implication and alternative deregulation pathways of BCL-6 expression remain to be determined.     

Transcriptional repressor BCL-6 immortalizes germinal center-like B cells in the absence of p53 function

Chromosomal rearrangements in non-Hodgkin's B-cell lymphoma implicate BCL-6 as an oncogene, yet direct evidence for BCL-6 acting as an oncogene in B cells has been lacking. Here, we show that BCL-6 can immortalize primary B cells, but only in the absence of p53 tumor suppressor function. The expression of BCL-6 led to greatly increased B-cell proliferation, particularly in response to CD40 stimulation. Furthermore, BCL-6-infected p53-deficient B cells gave rise to immortalized cell lines that could be maintained by CD40 stimulation. We found that in primary mouse B cells, BCL-6 repressed expression of the Blimp-1, p27kip1, and cyclin D2 target genes. BCL-6 did not markedly repress the PDCD2 and BCL-XL target genes. The BCL-6 immortalized cell lines had a phenotype consistent with germinal center B cells, they expressed the germinal center-specific M17 gene, and a significant fraction of the cells stained positive with PNA. Our data indicate that BCL-6 may act to maintain B cells in a germinal center-like state, and repression of Blimp-1 by BCL-6 may be particularly crucial for stabilization of the germinal center phenotype. Our data also suggest that disruption of the p53 pathway may be crucial for the development of BCL-6-expressing B-cell lymphomas.     

BCL-6 mRNA expression in higher grade transformation of follicle center lymphoma: correlation with somatic mutations in the 5' regulatory region of the BCL-6 gene.

Follicle center lymphoma (FCL) is an indolent low-grade B cell non-Hodgkin's lymphoma (NHL) that frequently transforms to aggressive diffuse large B cell lymphoma (DLBCL). Histological transformation of FCL is commonly associated with accumulation of secondary genetic alterations. The BCL-6 gene is commonly implicated in the pathogenesis of DLBCL and its expression may be altered by clonal rearrangements and somatic point mutations in its 5' non-translated regulatory region. Recently, somatic mutations of the BCL-6 gene were associated with the transformation process. Here, we examined BCL-6 mRNA expression and BCL-6 mutations in paired biopsies from the same patients obtained at the time of FCL diagnosis and after transformation. BCL-6 mRNA expression markedly increased upon transformation (1.9- to 4.8-fold) in three cases, remained unchanged in one case and decreased compared to the diagnosis FCL specimens in four cases. The three specimens that demonstrated an increase in the BCL-6 mRNA expression upon transformation harbored BCL-6 gene mutations in the 5' region of the first intron that overlapped with the previously reported negative regulatory region of the gene. Accumulation of new mutations in this region was not observed in DLBCL biopsies in which the BCL-6 mRNA expression did not increase. The present study demonstrates that although BCL-6 gene mutations do accumulate during the transformation process and, depending on their location within the first intron, may deregulate BCL-6 mRNA expression, increase in BCL-6 mRNA expression is not uniformly required for transformation from FCL to DLBCL.     

Combination of the MEK inhibitor pimasertib with BTK or PI3K-delta inhibitors is active in preclinical models of aggressive lymphomas

BackgroundLymphomas are among the most common human cancers and represent the cause of death for still too many patients. The B-cell receptor with its downstream signaling pathways represents an important therapeutic target for B-cell lymphomas. Here, we evaluated the activity of the MEK1/2 inhibitor pimasertib as single agent and in combination with other targeted drugs in lymphoma preclinical models.Materials and methodsCell lines derived mature B-cell lymphomas were exposed to increasing doses of pimasertib alone. Immunoblotting and gene expression profiling were performed. Combination of pimasertib with idelalisib or ibrutinib was assessed.ResultsPimasertib as single agent exerted a dose-dependent antitumor activity across a panel of 23 lymphoma cell lines, although at concentrations higher than reported for solid tumors. Strong synergism was observed with pimasertib combined with the PI3K inhibitor idelalisib and the BTK inhibitor ibrutinib in cell lines derived from diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma. The data were confirmed in an in vivo experiment treating DLBCL xenografts with pimasertib and ibrutinib.ConclusionThe data presented here provide the basis for further investigation of regimens including pimasertib in relapsed and refractory lymphomas.     

Novel murine B-cell lymphoma/leukemia model to study BCL2-driven oncogenesis

The BCL-2 family has been implicated in the pathogenesis of various hematopoietic malignancies, including follicular non-Hodgkin lymphoma and B-cell chronic lymphocytic leukemia. To identify genes that act synergistically in BCL2-enforced leukemogenesis, we developed a murine B-cell lymphoma/leukemia model based on the IL-3-dependent Balb/C pro-B line (FL5.12). FL5.12 cells were stably transfected with antiapoptotic BCL-2 alone or in combination with proapoptotic BAX or nonfunctional mutant BAX, thereby creating various levels of imbalance within the BCL-2 family. Transfectants were intravenously injected into normal Balb/C mice. Whereas FL5.12 cells did not provoke leukemia, mice injected with stable transfectants died of leukemia over time. Disease incidence and latency time depended on the degree of imbalance in the BCL-2 family, supporting a model whereby BCL2 drives tumorigenesis. All mice presented with hepatosplenomegaly and leukemic FL5.12 cells in peripheral blood and bone marrow compartments. Leukemic conversion was accompanied by secondary genetic aberrations leading to clonal IL-3-responsive leukemia. Cellular transformation was independent of alterations in c-Myc or downstream apoptotic pathway. Leukemic clones retained a normal DNA damage response leading to elevated P53 and P21 levels and cell cycle arrest upon irradiation. In conclusion, our mouse model may prove a valuable tool to identify genes that cooperate in BCL2-enforced lymphoma/leukemogenesis.     

结外NK/T细胞淋巴瘤发生的分子机制研究进展

结外NK/T细胞淋巴瘤(extranodal NK/T cell lymphoma,ENKTCL) 是我国继弥漫大B淋巴细胞淋巴瘤之后第二常见的非霍奇金淋巴瘤(non-hadgkin lymphoma,NHL).结外NK/T细胞淋巴瘤恶性程度高、临床进展快、预后差,对其发病机制的研究尤为重要.本文综述了近年来结外NK/T细胞淋巴瘤发生的分子机制研究进展,主要涉及该淋巴瘤的常见基因突变、NF-κB信号通路及JAK-STAT信号通路的主要激活机制.     

Application of Immunophenotyping and Heteroduplex Polymerase Chain Reaction (hPARR) for Diagnosis of Canine Lymphomas

Background: Canine malignant lymphoma is classified into B- or T-cell origin, as in the human case. Due to differences in prognosis, a suitable method needs to be developed for lineage identification. Aims: To determine the accuracy of immunophenotypic and molecular information between three methods: immunocytochemistry (ICC), immunohistochemistry (IHC) and heteroduplex polymerase chain reaction for antigen receptor rearrangements (hPARR) in spontaneous canine lymphomas. Materials and Methods: Peripheral blood, fine needle aspiration and tissue biopsies from enlarged peripheral lymph nodes prior to treatment of 28 multicentric lymphoma patients were collected. Cytopathology and histopathology were examined and classified using the updated Kiel and WHO classifications, respectively. Anti-Pax5 and anti-CD3 antibodies as B- and T-cell markers were applied for immunophenotyping by ICC and IHC. Neoplastic lymphocytes from lymph node and white blood cell pellets from peripheral blood were evaluated by hPARR. Results: In this study, low grade B-cell lymphoma accounted for 25% (7/28), high grade B-cell lymphoma for 64.3% (18/28) and high grade T-cell lymphoma for 10.7% (3/28). According to the WHO classification, 50% of all cases were classified as diffuse large B-cell lymphoma. In addition, ICC showed concordant results with IHC; all B-cell lymphomas showed Pax5+/CD3, and all T-cell lymphomas exhibited Pax5-/CD3+. In contrast to hPARR, 12 B-cell lymphomas featured the IgH gene; seven presented the TCRγ gene; five cases showed both IgH and TCRγ genes, and one case were indeterminate. Three T-cell lymphomas showed the TCRγ gene. The percentage agreement between hPARR and ICC/IHC was 60%. Conclusions: Immunophenotyping should not rely on a single method. ICC or IHC with hPARR should be used concurrently for immunophenotypic diagnosis in canine lymphomas.     

Expression of a soluble decoy receptor 3 in patients with diffuse large B-cell lymphoma predicts clinical outcome

The soluble decoy receptor 3 (DcR3) is a member of the TNF receptor superfamily. It is regarded as a decoy receptor released from tumor cells to escape host immune response by neutralizing the cytotoxic and immunomodulatory effects of FasL, LIGHT and TL1A. Overexpression of DcR3 has been observed in several human malignancies; however, only limited information exists on the role of DcR3 in non-Hodgkin lymphoma especially for B-cell origin. In the current study, the expression profile of DcR3 was analyzed by RT-PCR and immunohistochemistry (IHC) in a set of lymphoma cell lines including T-cell and B-cell lymphomas. The result demonstrated that overexpression of DcR3 was detected in most T-cell lymphoma cells, which was consistent with previous reports. Interestingly, overexpression of DcR3 was also detected both in the B-cell lymphoma cell lines and diffuse large B cell lymphoma (DLBCL) patients. DcR3 overexpression was associated with a worse prognosis in DLBCL patients (p=0.05). An in vitro study showed that neutralization of DcR3 increased the percentage of doxorubicin-mediated apoptosis in two B-cell lymphoma cell lines, which indicated the possibility of DcR3 mediated chemo-resistance in B-cell lymphomas. We suggest that overexpression of DcR3 is associated with a worse prognosis in DLBCL and the possible mechanism may act through the increase of chemo-resistance of lymphoma cells.     

Targeting BCL-2 in Hematologic Malignancies

Resistance to apoptosis is one of the hallmarks of cancer and members of the B-cell lymphoma 2 (BCL-2) family of proteins are central regulators of apoptosis. Many cancers become resistant to chemotherapy and apoptosis by up-regulating BCL-2 and other family members, making these proteins attractive targets for cancer therapy. Venetoclax is an orally administered, small-molecule apoptosis stimulant that targets BCL-2 proteins by acting as a BCL-2 homology domain 3 (BH3) mimetic. The drug is approved in the USA and EU as a monotherapy for the for the treatment of certain patients with chronic lymphocytic leukemia (CLL) and is in phase III clinical development for multiple myeloma (MM), and in phase II or I/II clinical trials for acute myeloid leukemia, and several B-cell malignancies, including diffuse large B-cell lymphoma, Waldenstrom's macroglobulinaemia, follicular lymphoma, and mantle-cell lymphoma.     

Primary follicular lymphoma of the testis in childhood

BACKGROUND: Follicular lymphoma in childhood is rare. The authors present four unusual primary follicular lymphomas of the testis in children. METHODS: Tumor tissue was evaluated using light microscopy, immunohistochemistry, flow cytometry, and polymerase chain reaction (PCR) for immunoglobulin heavy chain (IgH) and bcl-2 gene rearrangements. Southern blot and immunohistochemical analyses were used to detect bcl-6 gene rearrangements and protein expression, respectively. RESULTS: Four young boys ranging in age from 3 to 10 years were diagnosed with Stage IE follicular large cell lymphoma (Grade 3). A B-cell phenotype was documented in all four cases; monoclonality was confirmed in three cases by demonstration of light chain restriction or clonal IgH gene rearrangement. None of the lymphomas expressed Bcl-2 or p53 protein, and bcl-2 gene rearrangements were not found in the three lymphomas studied. In contrast, Bcl-6 protein was expressed by all three lymphomas studied, and a bcl-6 gene rearrangement was detected in the one case analyzed by Southern blot. All four boys were treated by orchiectomy and combination chemotherapy and are alive with no evidence of disease 18-44 months following their initial diagnoses. CONCLUSIONS: Follicular lymphomas may rarely occur as primary testicular tumors in prepubertal boys and, when localized, appear to be associated with a favorable prognosis. In contrast to follicular lymphoma in adults, pediatric follicular lymphomas of the testis are usually of large cell type (Grade 3) and lack bcl-2 or p53 abnormalities. The identification, in one case, of a bcl-6 gene rearrangement suggests an alternate molecular pathogenesis for pediatric follicular lymphoma.     

原发性皮肤淋巴瘤的临床病理学观察

目的 研究原发性皮肤淋巴瘤的临床表现、组织学特点及免疫表型.方法 对17例原发性皮肤淋巴瘤病例进行回顾性分析,按照世界卫生组织.欧洲癌症研究与治疗组织(WHO-EORTC)分类标准,结合形态和免疫组化结果对其进行分类.对不同类型的临床病理学特点分别进行观察、总结.结果 17例患者中,男性10例,女性7例.平均年龄为51(16～78)岁.患者均以发现皮肤病就诊.其中T细胞淋巴瘤14例,包括5例原发性皮肤间变性大细胞淋巴瘤,2例蕈样霉菌病,4例皮下脂膜炎样T细胞淋巴瘤及3例原发性皮肤外周T细胞淋巴瘤(其中1例为原发性皮肤侵袭性亲表皮性CD8+细胞毒性T细胞淋巴瘤).B细胞淋巴瘤3例,包括2例原发性皮肤弥漫大B细胞淋巴瘤(腿型)和1例原发性皮肤滤泡中心淋巴瘤(Ⅲ级).结论 原发性皮肤淋巴瘤临床表现及病理学特点复杂多样,两者必须紧密结合才能做出正确的诊断.