Lineage determination of CD20- B-Cell neoplasms: an immunohistochemical study

We studied 61 CD20- B-cell lymphomas, including 29 cases of precursor B-cell lymphoblastic leukemia/lymphoblastic lymphoma (B-ALL/B-LBL), 25 cases of CD20- recurrent mature B-cell lymphoma after rituximab therapy, and 7 cases of CD20- diffuse large B cell lymphoma (DLBCL). We used markers specific for B lineage: CD79a, Pax-5, OCT.2, and BOB.1. All B-ALL/B-LBLs expressed Pax-5 (29/29 [100%]), 25 (93%) of 27 expressed BOB.1, 23 (79%) of 29 expressed CD79a, and 6 (22%) of 27 expressed OCT.2. The percentages of cases expressing Pax-5, CD79a, OCT.2, and BOB.1 in CD20- recurrent mature B-cell lymphomas after rituximab treatment were 88% (21/24), 84% (21/25), 81% (17/21), and 73% (16/22), respectively. CD20- DLBCLs rarely express routine B-lineage markers, such as and CD79a and Pax-5, but they expressed OCT.2 or BOB.1. Pax-5, BOB.1, and CD79a antigens are the most reliable B-lineage markers for paraffin immunophenotyping B-ALL/B-LBL. CD79a and Pax-5 should be used as the first-line B lineage-specific markers for rituximab-treated CD20- mature B-cell lymphomas. If negative, OCT.2 or BOB.1 may be useful. The newly identified B-lineage markers, OCT.2 and BOB.1, may be the most useful for the B-lineage determination of CD20- plasmablastic or primary effusion subtypes of DLBCL.     

Primary cutaneous diffuse large B-cell lymphoma, leg type: diagnostic considerations

Context.-Primary cutaneous diffuse large B-cell lymphoma, leg type, may show features that overlap with other lymphomas. However, timely recognition of this entity can have important clinical and therapeutic implications. Objective.-To review the clinical, morphologic, and immunophenotypic characteristics of primary cutaneous diffuse large B-cell lymphoma, leg type, and juxtapose these features with other diagnostic considerations. In particular, other variants of primary cutaneous diffuse large B-cell lymphoma, as well as primary cutaneous follicle center lymphoma, will be reviewed. Additionally, systemic/extracutaneous lymphomas will be discussed, including diffuse large B-cell lymphoma, not otherwise specified, Epstein-Barr virus-positive diffuse large B-cell lymphoma of the elderly, and lymphomatoid granulomatosis. Data Sources.-Relevant literature will be reviewed and key differentiating findings will be highlighted. Conclusions.-Although primary cutaneous diffuse large B-cell lymphoma, leg type, may show aspects that overlap with other lymphomas, it can be distinguished from other entities in the differential diagnosis.     

CD5+ T-cell/histiocyte-rich large B-cell lymphoma.

CD5 expression in neoplastic large B-cells in T-cell/histiocyte-rich large B-cell lymphoma has not been reported, to the best of our knowledge. Here we describe the first case of CD5+ T-cell/histiocyte-rich large B-cell lymphoma that is well documented by histomorphology, immunohistochemistry, flow cytometry immunophenotyping and sorting, and immunoglobulin heavy-chain gene rearrangement study by polymerase chain reaction. The expression of CD5 in large neoplastic B-cells was demonstrated by immunohistochemistry and multicolor flow cytometry. The clonal nature of the CD5+ neoplastic B-cells was confirmed by rearranged immunoglobulin heavy (IgH) chain with polymerase chain reaction (PCR) of flow cytometry-sorted CD5+/CD19+/kappa+ cells. The CD5+ neoplastic large B-cells expressed bcl-6 and MUM1/IRF4 but not CD138 by immunohistochemistry. This suggests that the neoplastic cells may be of late germinal-center B-cell/ early post-germinal center B-cell origin. The patient responded to chemotherapy, CHOP (Cytoxan, doxorubicin, vincristine, and prednisone), and Rituxan very well and is currently in complete remission clinically. We propose that the current case, CD5+ T-cell/histiocyte-rich large B-cell lymphoma, represents a variant of recently reported de novo CD5+ diffuse large B-cell lymphomas. Our patient has had an excellent response to treatment; however, the clinical and biologic significance of CD5 expression in T-cell/histiocyte-rich large B-cell lymphoma requires further studies. Awareness of the CD5+ T-cell/histiocyte-rich large B-cell lymphoma variant will prompt pathologists to perform CD5 immunohistochemical stain in cases of T-cell/histiocyte-rich large B-cell lymphoma. This will lead to identifying more cases to understand the clinical and biologic characteristics of this variant.     

Primary testicular diffuse large B-cell lymphoma shows an activated B-cell-like phenotype

The most common type of primary testicular lymphoma is diffuse large B-cell type, which has a poor prognosis relative to other extra-nodal diffuse large B-cell lymphomas (DLBCL). These constitute a heterogeneous group of lymphomas with germinal center B-cell-like and activated B-cell-like subtypes. Such a distinction theoretically utilizes the immunohistochemical expression of CD10, Bcl-6, and MUM1. The purpose of this study was that we could stratify primary testicular lymphoma of diffuse large B-cell type according to this scheme, and further elucidate the reason why primary testicular diffuse large B-cell lymphoma possesses a poor clinical outcome. Seventeen Chinese patients with primary testicular DLBCL were examined by means of a 3-antibody panel (CD10, Bcl-6, MUM1). Among these 17 cases, 16 were assigned to the activated B-cell-like subtypes. One case was classified as germinal center B-cell-like type. Twelve of these 17 cases expressed high proliferative activity (≥40% Ki-67 labeling). The majority of primary testicular DLBCLs have activated B-cell-like subtype characteristics and high proliferative activity. These features might be a significant factor; moreover, they are associated with poor prognosis.     

Primary cutaneous B-cell lymphomas with large cell predominance–primary cutaneous follicle center lymphoma,diffuse large B-cell lymphoma,leg type and intravascular large B-cell lymphoma

In this review, we present clinical features and detailed histopathologic, immunologic, and molecular information regarding primary cutaneous follicle center lymphoma and primary cutaneous diffuse large B-cell lymphoma, leg type which together represent two of the three most common types of primary cutaneous B-cell lymphoma recognized in the current WHO classification system.1, 2 Overall, B-cell lymphomas represent 19–27% of primary cutaneous lymphomas in most large European and American studies3, 4, 5, 6 and together, primary cutaneous follicle center lymphoma and primary cutaneous diffuse large B-cell lymphoma, leg type account for approximately 2/3 to ¾ of these cases.5, 7, 8, 9, 10, 11 Both subtypes can contain a high content of large B-lymphocytes, although most cases of primary cutaneous follicle center lymphomas exhibit a range in cell size and cytology. Intravascular large B-cell lymphoma, a less commonly-encountered EBV-negative primary cutaneous B-cell lymphoma composed of large cells, will be more briefly discussed in this report as well.     

Expression of HGAL in primary cutaneous large B-cell lymphomas: evidence for germinal center derivation of primary cutaneous follicular lymphoma.

The classification of primary cutaneous large B-cell lymphoma (PCLBCL) is based on standard morphology, immunohistochemistry, and clinical presentation. There are two major subtypes in the current WHO-EORTC classification: follicle center lymphoma and diffuse large B-cell lymphoma, leg-type (DLBCL-LT). The goals of this study were to examine a series of DLBCLs to determine (1) whether the immunohistochemical paradigm of germinal center B-cell and non-germinal center B-cell types of systemic DLBCL could be applied to PCLBCL; (2) whether application of the newly described germinal center B-cell marker, human germinal center-associated lymphoma (HGAL) also discriminates between these types as a further support for germinal center B-cell origin for primary cutaneous center lymphoma; and (3) whether any of these biologic markers were of prognostic significance. To this end, 32 cases of diffuse PCLBCL (22 primary cutaneous follicular center lymphomas and 10 DLBCL-LT) were classified based on the WHO-EORTC criteria and studied for expression of CD20, BCL2, BCL6, CD10, MUM-1, and HGAL by immunohistochemistry. Results were correlated with clinical features. HGAL and BCL6 expression and germinal center B-cell phenotype were associated with primary cutaneous follicular center lymphoma. The combination of HGAL and BCL6 positivity had the highest sensitivity (88%) and specificity (100%) for predicting subtype compared to either marker alone. Both HGAL and BCL6 were associated with the germinal center B-cell phenotype. The correlation of HGAL expression with the germinal center B-cell phenotype demonstrates the role of this marker in the classification of cutaneous large B-cell lymphomas. BCL6 expression was the only immunohistochemical marker associated with overall survival. Characterizing PCLBCLs with markers of B-cell maturation stage is a useful framework for studying, classifying, and clinically stratifying these lymphomas.     

New monoclonal antibodies against B-cell antigens: possible new strategies for diagnosis of primary cutaneous B-cell lymphomas

Reactivities of the monoclonal antibodies (mAbs) of the 9th Human Leukocyte Differentiation Antigen Workshop, in order to define specific antigenic expression of the primary cutaneous B-cell lymphomas (PC-BCL), were analyzed by immunohistology on human tonsil and on PC-BCL, such as follicular centre B-cell lymphomas (FCL), marginal zone lymphomas (MZL) and diffuse large B-cells lymphomas leg-type (DLBL-LT). We identified some subgroups of mAbs that were exclusively or preferentially positive in one lymphoma cell type: the PC-FCL subgroup of mAbs includes PD1/CD279, GCET-1, hFCRL1/CD307a, FCRL2/CD307b, CXCR5/CD185, B7-DC/CD273, MRC/CD200, CD130, CXCR4/CD184, Siglec-5/14, CD150, on the other hand subgroup of mAbs in PC-MZL includes BTLA/CD272, BLIMP-1, hCD38. No specific subgroup of mAbs was found to label PC-DLBCL. This study may be useful to better define specific antigen profile of different PC-BCL entities leading to a correct diagnosis.     

Expression of TP73L is a helpful diagnostic marker of primary mediastinal large B-cell lymphomas.

Primary mediastinal large B-cell lymphoma is a well-defined lymphoma entity whose molecular pathogenesis is incompletely understood and also lacking well-established diagnostic markers. Recently, the presence of overlapping features between classical Hodgkin's lymphoma and primary mediastinal large B-cell lymphoma was highlighted by gene expression profiling as well as morphological studies. We investigated the expression of TP73L (commonly known as p63) isoforms in primary mediastinal large B-cell lymphoma at both protein and mRNA level, and demonstrated the exclusive presence of transactivating (TA) isoforms in all cases. We also demonstrated that TP73L is expressed in a subset of germinal center B-cells, as well as in some diffuse large B-cell lymphomas, but it is never present in classical Hodgkin lymphoma. Nodular lymphocyte predominant Hodgkin's lymphoma also showed TP73L positivity by immunohistochemistry. Isoform analysis by real-time PCR showed that TA-TP73Lalpha is the most represented in primary mediastinal large B-cell lymphoma, but TA-TP73Lgamma is the most differentially expressed in comparison to both germinal center B-cells and diffuse large B-cell lymphomas. TP73L expression proved a useful diagnostic marker of primary mediastinal large B-cell lymphoma, and gave new insights in to the molecular pathways playing a role in this lymphoma.     

Primary breast diffuse large B-cell lymphoma shows a non-germinal center B-cell phenotype.

Primary breast diffuse large B-cell lymphoma has a poor prognosis relative to other extranodal diffuse large B-cell lymphoma. Recently, diffuse large B-cell lymphoma has been subclassified as germinal center B-cell-like and nongerminal center B-cell types using tissue microarrays. The 5-year overall survival rate of the germinal center B-cell group is better than that of the nongerminal center B-cell group. To elucidate the reason for which primary breast diffuse large B-cell lymphoma has a poor clinical outcome, we investigated 15 patients with primary breast diffuse large B-cell lymphoma (stage IE; 13 cases, stage IIE; two cases) by immunohistochemistry using various markers including CD10, Bcl-6, MUM1 and MIB-1 and by molecular analysis of the immunoglobulin heavy chain gene variable region. Immunohistochemistry showed 0/15 (positive cases/examined cases) for CD10, 5/15 for Bcl-6, 15/15 for MUM1, 10/15 for Bcl-2, 2/15 for CD5 and 4/15 for CD40. The expression pattern of CD10(-) MUM1(+) in primary breast diffuse large B-cell lymphoma corresponded to the nongerminal center B-cell group. Moreover, the MIB-1 index was distributed from 60 to 95% with a mean of 79%, indicating a high proliferation of the lymphoma cells. The immunoglobulin heavy chain gene variable region of primary breast diffuse large B-cell lymphoma had a mutation frequency of 1-10% (seven cases) and 0-1 additional mutations in ongoing mutation analysis (five cases). Primary breast diffuse large B-cell lymphoma had characteristics of the nongerminal center B-cell group. In conclusion, primary breast diffuse large B-cell lymphoma has a nongerminal center B-cell phenotype and has a high MIB-1 index. These features might therefore be associated with poor prognosis.     

Intravascular large B-cell lymphoma

A rare type of diffuse large B-cell lymphoma, intravascular large B-cell lymphoma primarily affects the middle-aged to elderly population, with a slight predominance in men. By the time of presentation, most patients have advanced, disseminated disease, and often the diagnosis is made at autopsy. Patients may present with any of a myriad of symptoms, with any tissue potentially being infiltrated. Central nervous system and cutaneous involvement is common, as is the presence of B symptoms including fever, weight loss, and night sweats. Morphologically, growth of neoplastic cells is restricted to the lumen of small vessels. The cells are large, with 1 or more prominent nucleoli, scant cytoplasm, and frequent mitotic figures, and are commonly positive for cluster of differentiation markers 79a, 20, and 19, as well as MUM1/IRF4 and Bcl-2. Intravascular large B-cell lymphoma is aggressive, and without treatment is rapidly fatal.     

B-cell non-Hodgkin lymphomas in Uganda: an immunohistochemical appraisal on tissue microarray

The most common non-Hodgkin lymphomas in Uganda are neoplasms of B-cell derivation. The field of B-cell lymphoma immunophenotype has rapidly progressed because of the increasing availability of markers applicable to routine sections. Although the latter have allowed the identification of distinctive lymphoma entities in the developed countries, such approach has not yet been used in Uganda. One hundred twenty-nine formalin-fixed, paraffin-embedded tissue samples from the Department of Pathology of Makerere University were used for tissue micro-array (TMA) construction. Four-micrometer-thick sections were cut from TMAs and stained with hematoxylin and eosin and Giemsa. They were also used for immunohistochemistry and in situ hybridization. According to morphology and immunohistochemistry, lymphoid neoplasms were classified as Burkitt's lymphoma (BL) (95 cases), diffuse large B-cell lymphoma (19 cases), mantle cell lymphoma (4 cases), and B-cell lymphoblastic lymphoma (1 case). In BL, a homogeneous phenotype (CD10(+), Bcl-6(+), Bcl-2(-), MUM1/IRF4-, and Ki-67 approximately 100%) and a stable Epstein-Barr virus integration were found. A distinctive and unusual feature was the frequent plasma cellular differentiation, along with the positivity for CD30 and CD138 (recorded in 35 and 43 cases, respectively). According to our findings, most non-Hodgkin B-cell tumors in Uganda are endemic BLs followed by diffuse large B-cell lymphomas. The rest consist of rare but clinically important entities such as mantle cell lymphoma and B-cell lymphoblastic lymphoma. The availability of TMAs and immunohistochemistry has enabled us to precisely categorize tumors that have so far been diagnosed in Uganda as "high-grade/aggressive" lymphomas on the basis of cell morphology alone.     

Mutational analysis of the 5' noncoding region of the bcl-6 gene in primary gastric lymphomas.

Bcl-6 mRNA and protein are frequently expressed in the transformed counterparts of the germinal center B-cells, diffuse large B-cell lymphoma and follicular lymphoma, irrespective of the gene rearrangements. Most of the primary gastric lymphomas are thought to be of mucosa-associated lymphoid tissue (MALT) origin, and neither bcl-6 gene rearrangement nor protein expression is found in low-grade gastric lymphomas of the MALT type as in normal marginal zone cells. However, bcl-6 protein expression was identified in high-grade gastric lymphomas, suggesting its role in high-grade transformation. In this study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis for bcl-6 primer was performed in order to ascertain the molecular mechanisms of bcl-6 protein expression in primary gastric lymphomas. A total 31 cases of gastric lymphoma were classified into low-grade gastric lymphomas of MALT type (n = 13), high-grade gastric lymphomas of MALT type (n = 6) and gastric diffuse large B-cell lymphomas (n = 12). Bcl-6 mutations were observed in 11 of 13 (84.6%) low-grade gastric lymphomas of the MALT type and in 8 of 12 (66.7%) diffuse large B-cell gastric lymphomas. In 6 cases of the high-grade gastric lymphomas of the MALT type, both the low- and high-grade components demonstrated the same frequency (3/6, 50%) of mutations. The tissue obtained from the marginal zone of Peyer's patch by microdissection technique revealed no bcl-6 mutations by the PCR-SSCP analysis. These findings suggest that the acquisition process of bcl-6 mutations by the marginal zone cells may be involved in the lymphomagenesis of the stomach, but our data does not explain the reason why bcl-6 protein is expressed only in high-grade gastric lymphomas.     

Jaw1/LRMP, a germinal centre-associated marker for the immunohistological study of B-cell lymphomas

Jaw1, also known as lymphoid-restricted membrane protein (LRMP), is an endoplasmic reticulum-associated protein. High levels of Jaw1/LRMP mRNA have been found in germinal centre B-cells and in diffuse large B-cell lymphomas of 'germinal centre' subtype. This paper documents Jaw1/LRMP expression at the protein level in human tissues by immunohistochemical and western blotting analysis using an antibody reactive with paraffin-embedded tissues. Jaw1/LRMP was highly expressed in germinal centre B-cells (in keeping with gene expression data), in 'monocytoid B-cells', and in splenic marginal zone B-cells. It was absent, or present at only low levels, in mature T-cells, although cortical thymocytes were weakly positive. Among lymphoid neoplasms, Jaw1/LRMP was found in germinal centre-derived lymphomas (follicle centre lymphoma, Burkitt's lymphoma, lymphocyte-predominant Hodgkin's disease) but not in T-cell neoplasms (with the exception of a single T lymphoblastic lymphoma). Classical Hodgkin's disease and myeloma lacked Jaw1/LRMP but many cases of chronic lymphocytic leukaemia (but not mantle zone lymphoma) were Jaw1/LRMP-positive. Approximately half of the marginal zone lymphomas were Jaw1/LRMP-positive. In diffuse large B-cell lymphomas, Jaw1/LRMP was found in three-quarters (24/32) of the cases classified phenotypically as being of 'germinal centre' type, but it was also expressed in almost half (13/28) of the 'non-germinal centre' cases. A similar proportion of 'non-germinal centre' cases were positive for the protein products of two other genes expressed highly in germinal centre cells (HGAL/GCET2 and PAG). The fact that all three of these proteins are expressed in a significant proportion of diffuse large B-cell lymphomas assigned to the 'non-germinal centre' category indicates that the immunophenotypic categorization of diffuse large B-cell lymphoma according to cellular origin may be more complicated than currently understood. Finally, the expression of Jaw1/LRMP in other types of lymphoma and in non-lymphoid tissues/tumours may be of interest in differential diagnosis and research.     

Expression of Grb2 distinguishes classical Hodgkin lymphomas from primary mediastinal B-cell lymphomas and other diffuse large B-cell lymphomas

Growth factor receptor-bound protein 2 is an adaptor molecule that mediates B-cell receptor (BCR) signaling pathways, but the expression of growth factor receptor-bound protein 2 in lymphoma tissues has not been reported. We sought to characterize growth factor receptor-bound protein 2 protein expression in reactive tonsillar tissues and lymphoma tissues obtained from diagnostic biopsies of classical Hodgkin lymphoma, primary mediastinal large B-cell lymphoma, diffuse large B-cell lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and 20 low-grade B-cell lymphomas. Growth factor receptor-bound protein 2 expression was assessed in tissues by immunohistochemistry and in lymphoma cell lines by immunoblotting. In reactive lymphoid tissues, growth factor receptor-bound protein 2 was expressed in the cytoplasm of B-cells and histiocytes but not T-cells. Strong, cytoplasmic growth factor receptor-bound protein 2 expression was seen in the neoplastic cells of follicular lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, splenic marginal zone lymphoma, primary mediastinal large B-cell lymphoma, diffuse large B-cell lymphoma, and nodular lymphocyte predominant Hodgkin lymphoma. In contrast, only 10% of the classical Hodgkin lymphomas showed growth factor receptor-bound protein 2 expression in the neoplastic cells. Growth factor receptor-bound protein 2 protein expression was detected by Western blotting in all lymphoma cell lines tested with higher levels in primary mediastinal large B-cell lymphoma compared with classical Hodgkin lymphoma cell lines. These findings support a role for growth factor receptor-bound protein 2 in the diagnostically challenging workup of classical Hodgkin lymphoma versus primary mediastinal large B-cell lymphoma and warrant further studies to evaluate the biologic significance of growth factor receptor-bound protein 2 in the pathogenesis of classical Hodgkin lymphoma.     

Coexpression of Bcl-6 and CD10 in diffuse large B-cell lymphomas: significance of Bcl-6 expression patterns in identifying germinal center B-cell lymphoma

Most follicular lymphomas (FLs) transform to diffuse lymphoma eventually, comprising a significant proportion of diffuse large B-cell lymphoma (DLBCL). Judging by bcl-2 rearrangement (bcl-2R), one third of DLBCLs are believed to be of FL derivation in the Western population. However, bcl-2R is not specific and is not detectable in every case of FL. In East Asia, FL is uncommon but DLBCL is not. The proportion of tumors of FL origin in DLBCL is not known in this region. The coexpression of Bcl-6 and CD10 proteins, a reliable marker to identify germinal center (GC) B-cell lymphoma including FL, was analyzed in primary nodal DLBCLs (n = 104) diagnosed at major hospitals in Seoul during a recent 2-year period, along with well-defined cases (n = 17) of nodal FL as controls. Bcl-2 protein expression (n = 77) was also studied along with bcl-2R (n = 64), by polymerase chain reaction. Formalin-fixed archival specimens were used in all these assays. The Bcl-6/CD10 coexpression was observed in 35 DLBCLs (34%) and 14 FLs (82%), and most of them showed a pattern of Bcl-6 expression similar to that of the GC. Bcl-2 expression or bcl-2R did not correlate with Bcl-6/CD10 coexpression. Histologically, compartmentalizing sclerosis was associated with a high rate of the coexpression (8 of 10). In conclusion, to detect GC B-cell lymphoma in routine biopsy specimens, a pattern of Bcl-6 staining similar to the GC must be identified. Bcl-6+/CD10+ GC B-cell lymphomas thus defined comprised one third of primary nodal DLBCLs in Korea. The incidence rate is similar to that in the West. The reasons for the discrepancy between the incidence of GC B-cell lymphoma and the paucity of the follicular pattern in East Asian subjects warrant further studies.