Critical evaluation of Bcl-6 protein expression in diffuse large B-cell lymphoma of the stomach and small intestine

Diffuse large B-cell lymphoma (DLBCL) of the gastrointestinal tract is heterogeneous, including mucosa-associated lymphoid tissue (MALT) origin and non-MALT, and they are indistinguishable. MALT lymphoma is a tumor of a post-germinal center (GC) memory B-cell origin, which is negative for Bcl-6 protein expression in low-grade but may become positive in high-grade tumors. Because Bcl-6 expression patterns in lymphoma of GC and non-GC B-cell origins have recently been characterized and CD10 is generally regarded as a specific marker for GC B cells, we critically evaluated gastric and small intestinal DLBCLs to see whether it is possible to identify tumor of GC B-cell origin by immunostaining in archival specimens. High-grade MALT lymphoma (H-ML) of the stomach (n = 20) was defined by the presence of a concomitant lymphoepithelial lesion and/or follicular colonization; and DLBCLs de novo, both gastric (n = 31) and intestinal (n = 21), were defined by the absence of the above features. Immunostaining for Bcl-6 and CD10 was done using formalin-fixed, paraffin-embedded sections and was examined independently by three pathologists. Staining for Bcl-6 was positive (>10% of tumor cells) in 55 of 72 cases. However, two distinct patterns were recognized among those positive: diffusely dense (>75%) and sporadic (<75%). The former was further characterized by a consistency of Bcl-6+ tumor cell density at any given area, resembling the staining pattern of the GC or follicular lymphoma (FL) (GC/FL pattern), whereas the latter was, besides less dense population, by variable density from area to area. The GC/FL pattern was observed in 36% and 38% of gastric and intestinal DLBCLs de novo, respectively, but in none of the gastric H-ML. CD10 was positive in 12 of 71 cases (17%), all coexpressing Bcl-6. CD10+ tumors were more frequent in the intestinal (33%) than in gastric DLBCLs ( approximately 15%). Significantly, CD10 expression was observed in three gastric H-MLs, including one that displayed a distinct lymphoepithelial lesion. In conclusion: 1). tumors showing a diffusely dense pattern of Bcl-6 expression should be distinguished from those showing a sporadic pattern; for the former most likely represents the tumor of GC B-cell derivation, and the latter non-GC, including MALT lymphoma; 2). tumor of GC B-cell origin thus defined accounted for about one third of gastric as well as intestinal DLBCLs de novo but none of the gastric H-ML; and 3). CD10 expression can be seen in MALT lymphomas and should not be used as the marker for GC B cells.     

Primary bone marrow lymphoma: an uncommon extranodal presentation of aggressive non-hodgkin lymphomas

Bone marrow involvement by lymphoma is considered a systemic dissemination of the disease arising elsewhere, although some tumors may arise primarily in the bone marrow microenvironment. Primary bone marrow lymphoma (PBML) is a rare entity whose real boundaries and clinicobiological significance are not well defined. Criteria to diagnose PBML encompass isolated bone marrow infiltration, with no evidence of nodal or extranodal involvement, including the bone, and the exclusion of leukemia/lymphomas that are considered to primarily involve the bone marrow. Twenty-one out of 40 lymphomas retrospectively reviewed by the International Extranodal Lymphoma Study Group from 12 institutions in 7 different countries over a 25-year period fulfilled the inclusion criteria. These cases comprised 4 follicular lymphomas (FLs), 15 diffuse large B-cell lymphomas (DLBCLs), and 2 peripheral T-cell lymphomas, not otherwise specified. The FL cases showed paratrabecular infiltration, BCL2 protein and CD10 expression, and BCL2 gene rearrangement. DLBCL showed nodular infiltration in 6 cases and was diffuse in 9 cases; it also showed positivity for BCL2 protein (9/10) and IRF4 (6/8). Median age was 65 years with male predominance. All but 3 FL patients were symptomatic. Most cases presented with cytopenias and high lactate dehydrogenase. Four patients (3 FL cases and 1 DLBCL case) had leukemic involvement. Most DLBCL patients received CHOP-like or R-CHOP-like regimens. The outcome was unfavorable, with a median overall survival of 1.8 years. In conclusion, PBML is a very uncommon lymphoma with particular clinical features and heterogenous histology. Its recognition is important to establish accurate diagnosis and adequate therapy.     

T-cell/histiocyte-rich large B-cell lymphoma: a heterogeneous entity with derivation from germinal center B cells

T-cell/histiocyte-rich large B-cell non-Hodgkin's lymphoma (THRLBCL) is an unusual morphologic variant of diffuse large B-cell lymphoma. We reviewed 30 cases of THRLBCL to evaluate its heterogeneity based on morphologic, immunophenotypic, and genetic features. Cases were classified according to the appearance of the large neoplastic B cells into three morphologic variants: 1) lymphocytic and histiocytic (L&H-like) (resembling the L&H cells of nodular lymphocyte predominance Hodgkin's lymphoma (14 cases); 2) centroblast (or immunoblast)-like (10 cases), and 3) Reed-Sternberg cell-like (resembling the neoplastic cells of classic Hodgkin's lymphoma) (6 cases). We used a panel of immunohistochemical stains, including those with specificity for germinal center B cells: CD20, CD79a, CD30, CD15, epithelial membrane antigen, BCL-2, BCL-6, and CD10. The /JH polymerase chain reaction assay was further performed to investigate a relationship to follicular lymphoma. The results were correlated with Epstein-Barr virus status as determined by staining for latent membrane protein and EBER-1 in situ hybridization. All cases were of B-cell immunophenotype with strong surface CD20 reactivity in the neoplastic large lymphoid cells, although CD79a was more inconsistently and weakly expressed (10 of 17). Nuclear positivity for the BCL-6 protein was detected in the tumor cells in 26 of 29 (90%) cases. However, differences in expression of other antigens were encountered in the histologic subtypes. Epithelial membrane antigen positivity, a feature often seen in nodular lymphocyte predominance Hodgkin's lymphoma, was observed in 11 of 30 (37%) cases and was most commonly seen in cases with L&H cell morphology (8 of 14; 57%). CD30 expression was observed in 9 of 30 (30%) cases but was most frequent in cases with Reed-Sternberg-like morphology (3 of 6 [50%]). CD10 expression was infrequent overall (3 of 29; 10%), with 2 of 3 positive cases identified in the centroblastic group. The overall rarity of positivity for CD10, BCL-2 (3 of 22; 13%), and -2 JH rearrangement (1 of 28; 4%) indicates a lack of connection to follicular lymphoma for all subtypes. The three cases that were negative for BCL-6 protein were LMP-1 positive and EBER-1 positive by in situ hybridization, and 2 of 3 had neoplastic cells with Reed-Sternberg-like morphology. These results demonstrate that although a large proportion of THRLBCL represent tumors of germinal center B cell derivation, they exhibit a diversity of morphologic and immunophenotypic features. A subset of THRLBCL may be related to nodular lymphocyte predominance Hodgkin's lymphoma. A small percentage show features closely resembling classic Hodgkin's lymphoma and could be considered a variant of grey zone lymphoma.     

Cutaneous b-cell lymphomas of follicular and marginal zone types: use of Bcl-6, CD10, Bcl-2, and CD21 in differential diagnosis and classification

Cutaneous follicular lymphomas (FLs) and cutaneous B-cell lymphomas of extranodal marginal zone (MZL)/mucosal-associated lymphoid tissue (MALT) type may have morphologic overlap, despite the fact that they are thought to be of distinct derivation (germinal center vs. postgerminal center). The problem is compounded by the reported absence of bcl-2 expression by many cutaneous FLs, leading to speculation that cutaneous FL may be unrelated to nodal FL. The authors analyzed the expression of the germinal center-associated antigens bcl-6 and CD10 and of bcl-2 in 18 cutaneous B-cell lymphomas (10 FLs and eight MZLs), in relationship to CD21+ follicular structures, to clarify the relationship of nodal to cutaneous FLs and to explore the value of these antigens in differential diagnosis. The authors studied 10 cutaneous FLs (seven primary and three secondary) and eight MZLs (six primary and two secondary). The FLs (found in six men and four women age 45-75 years) involved the trunk (n = 3) and scalp, face and neck (n = 7). The MZLs (found in five women and three men age 34-81 years) involved the trunk (n = 4), face and neck (n = 2), and arm (n = 2). Immunostaining for CD21, bcl-6, CD10, and bcl-2 allowed the delineation of compartments within the tumors and yielded distinct patterns of staining in FL and MZL. In both follicular and interfollicular/diffuse areas of FL the neoplastic cells were bcl-6+ (10 of 10), often CD10+ (seven of 10, four of seven primary), and bcl-2+ (nine of 10, six of seven primary). Only three of seven cases (one of five primary) had bcl-2 rearrangement detectable by polymerase chain reaction. In the MZLs, the neoplastic B-cells were bcl-6-, CD10-, and bcl-2+ (eight of eight). Three patterns of CD21+ follicles were identified in MZL: reactive germinal centers, uniformly bcl-6+, CD10+, and bcl-2- (five of eight MZLs); colonized follicles, both bcl-6-, bcl-2+, and L26+ cells, and bcl-6+ and bcl-2- cells (five of eight MZLs); and expanded/colonized follicular dendritic cell meshworks, bcl-6- and bcl-2+ B cells with rare residual bcl-6+ and bcl-2- cells (four of eight MZLs). The authors conclude that cutaneous FLs express bcl-6 uniformly, usually express CD10 and bcl-2, and have a follicular pattern similar to nodal FL and consistent with a germinal center origin. The immunophenotype of cutaneous FL is distinct from that of cutaneous MZL, which is negative for bcl-6 and CD10. Colonized follicles in MZL, identified by CD21+ follicular dendritic cell meshworks, contained numerous bcl-6- and bcl-2+ B cells, and were readily distinguished from neoplastic follicles in FL. Conversely, CD21- interfollicular and diffuse areas in FLs contained bcl-6+ and CD10+ cells, which were not seen in diffuse areas of MZLs. Thus, the combination of bcl-2, bcl-6, and CD21 staining is useful for the distinction of cutaneous MZL from cutaneous FL.     

Cutaneous marginal zone lymphomas have distinctive features and include 2 subsets

Cutaneous marginal zone lymphomas (CMZL) were segregated in the WHO/EORTC consensus classification but grouped with other MALT lymphomas in the subsequent WHO classification. It has been suggested, however, that CMZL have distinctive features and might include 2 subsets. To address these issues, the clinicopathologic, phenotypic and, when possible, genotypic features of 29 CMZL with plasmacytic differentiation were assessed. The monotypic plasma cells had class-switched heavy chain expression in 22 cases, technically inadequate staining in 1 case (included with class-switched cases for analysis) and 6 were IgM. The class-switched cases had a predominance of T cells in 22 out of 23 cases with a CD4:CD8>1 in 15 out of 16 cases, usually showed nodules and scattered small B cells often with IgD apparently nonneoplastic follicles, lacked CXCR3 B-cell expression, never showed a totally diffuse growth pattern, often had prominent mast cells, and lacked known extracutaneous involvement. The IgM cases showed a predominance of B cells in 5 out of 6 (P=0.0003), a diffuse proliferation of CD20 B cells in all (P<0.0001), CXCR3+ B cells in 2 out of 5 (P<0.04), and extracutaneous disease in 3 out of 6 (P<0.008). CD21 usually disrupted follicular dendritic meshworks were seen in 9 out of 12 class-switched and 5 out of 5 IgM cases. CD123 plasmacytoid dendritic cells, PD1+ T follicular helper cells, CD25 or FOXP3+ regulatory T cells, and TIA1/granzyme B cytotoxic cells were never numerous. Only 1 out of 14 tested cases showed a low-level clonal/oligoclonal T cell receptor γ gene rearrangement. These findings support the presence of 2 types of cutaneous MALT lymphomas with the class-switched cases being the most distinctive but still sharing significant features with MALT lymphomas from other sites, specifically an extranodal extramedullary CD5-, CD10- indolent small B cell lymphoma with plasmacytic differentiation, frequent benign follicular structures, and not fulfilling the criteria for any other well-defined lymphoma.     

Primary and secondary cutaneous diffuse large B-cell lymphomas: a multiparameter analysis of 25 cases including fluorescence in situ hybridization for t(14;18) translocation

Although primary cutaneous diffuse large B-cell lymphomas (DLBCLs) except for those of the leg are grouped together with primary cutaneous follicle center cell lymphoma in the European Organization for Research and Treatment of Cancer classification of primary cutaneous lymphomas, they typically lack the usual phenotypic profile of follicular lymphoma. Whether they are truly of follicular center cell origin, have a molecular pathogenesis similar to nodal follicular lymphoma, or have any biologic features that distinguish them from secondary DLBCL involving skin remains uncertain. To address these issues, a retrospective multiparameter study of 25 patients including clinical, histologic, immunophenotypic, and cytogenetic analyses was performed. A classic CD10+, bcl-6+ follicular center cell profile was found in 10 (40%) cutaneous DLBCL (2 of 11 primary, 5 of 8 secondary, 3 of 6 unclassified) with bcl-2 expression seen only in the nonprimary cases. Of the remaining cases, 14 cases (56%) were CD10-, bcl-6+, bcl-2+/- (9 primary) and one case (4%) was CD10-, bcl-6-, bcl-2+ (0 primary). Fluorescence in situ hybridization analysis showed a t(14;18) in 0 of 9 primary and 3 of 5 secondary cases. Primary cases were frequently found in the head/neck region, whereas secondary cases were more common on the trunk and extremities. Patients with primary disease were all alive, usually having received only local therapy, at a median follow-up of 19 months. Most secondary cases were treated with chemotherapy with only one untreated patient dead of disease at a median follow-up of 5 months. Primary cutaneous DLBCLs therefore appear to be distinctive as they have fewer features of follicular lymphoma than do secondary cases. Nevertheless, some appear to be of follicular center cell origin, even though they probably have a different molecular pathogenesis than most nodal follicular lymphomas.     

Malignant lymphoma of the thyroid gland: a clinicopathologic study of 108 cases

We report a retrospective clinicopathologic study of 108 primary thyroid gland lymphomas (PTLs), classified using the REAL and proposed WHO classification schemes. The patients included 79 women and 29 men, with an average age of 64.3 years. All patients presented with a thyroid mass. The PTLs were classified as marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) or MZBL (n = 30), diffuse large B-cell lymphoma (DLBCL) with MZBL (n = 36), DLBCL without MZBL (n = 41), and follicle center lymphoma (FCL; n = 1). Excluding the FCL, features of lymphomas of MALT-type were identified in all groups, despite a follicular architecture in 23% of cases. Lymphocytic thyroiditis (LT) was identified in 94%. Ninety-one percent of patients presented with stage IE or IIE disease, whereas 69% had perithyroidal soft tissue infiltration. All patients were treated with surgical excision followed by adjuvant therapy (76%): chemotherapy (15%), radiation (19%), or a combination of radiation and chemotherapy (42%). Disease-specific survival was 82% at last follow up (mean, 82.8 mos) and 79% at 5 years. Statistically, stages greater than IE, presence of DLBCL, rapid clinical growth, abundant apoptosis, presence of vascular invasion, high mitotic rate, and infiltration of the perithyroidal soft tissue were significantly associated with death with disease. No patients with MZBL or stage IE disease died with disease. In summary, PTLs typically occur in middle- to older-aged individuals as a thyroid mass, with a predilection for females. Despite their histologic heterogeneity and frequent simulation of other lymphoma subtypes, virtually all PTLs are lymphomas of MALT-type arising in the setting of LT. Mixed DLBCL and MZBL are common. Overall, PTLs have a favorable outcome with appropriate therapy, but prognosis depends on both clinical stage and histology. MZBL and stage IE tumors have an excellent prognosis, whereas tumors with a large cell component or DLBCL or stage greater than IE have the greatest potential for a poor outcome.     

Pyothorax-associated lymphoma: a peculiar clinicopathologic entity derived from B cells at late stage of differentiation and with occasional aberrant dual B- and T-cell phenotype

We report 12 European cases of pyothorax-associated lymphomas occurring 30-67 years following artificial pneumothorax for pleuropulmonar tuberculosis. Eleven patients presented with a localized pleural tumor mass, whereas one patient also had liver involvement. Histologic examination showed a diffuse proliferation of large lymphoid cells with frequent plasmacytoid differentiation (n = 8), expressing CD20 (n = 10), CD79a (n = 11), and/or CD138 (n = 5) B-cell antigens. Aberrant expression of T-cell markers (CD2, CD3, CD4) was noted in five cases. The B-cell origin of lymphoma cells was confirmed by the demonstration of immunoglobulin light chain restriction or clonal B cell population in six cases. In 11 of 12 cases in situ hybridization disclosed Epstein-Barr virus genome in most tumor cells and immunohistochemistry a type III LMP-1+/ EBNA-2+ latency profile. HHV-8/ORF73 antigen was not detected in all tested cases (n = 11). All investigated cases (10 of 10) disclosed a uniform CD10-/BCL-6-/MUM1+/CD138+/- phenotype, consistent with a derivation from late germinal center (GC)/post-GC B cells. Clinical outcome was poor with a median survival time of 5 months. Only one patient was in complete remission after 34 months. This study further confirms that pyothorax-associated lymphoma represents a distinct clinicopathologic entity among diffuse large B-cell lymphoma, which is characterized by a peculiar clinical presentation, frequent plasmacytoid features, and a strong association with EBV. Moreover, we show that this lymphoma entity likely originates from B cells at a late stage of differentiation and occasionally shares an aberrant dual B/T phenotype.     

Lymphomas involving the breast: a study of 106 cases comparing localized and disseminated neoplasms

Lymphomas involving the breast account for approximately 2% of extranodal and <1% of all non-Hodgkin lymphomas. Our aim in this study was to classify breast lymphomas using the World Health Organization classification and then compare this classification with clinical, histologic, and radiologic findings as well as survival. The study group included 106 patients with breast lymphoma (105 women and 1 man). The neoplasms were divided into 2 groups based on extent of disease at initial diagnosis: localized disease (n=50) and disseminated disease (n=56). The follow-up period ranged from 4 to 252 months (median, 49 mo). Almost all (97%) patients presented with a palpable breast mass or masses. In the localized group, diffuse large B-cell lymphoma (DLBCL) was most frequent (n=32, 64%). In the disseminated group, follicular lymphoma was most frequent and exclusive to this group (P=0.0004). Mucosa-associated lymphoid tissue lymphomas occurred in both groups without a significant difference in frequency. A variety of other types of B-cell and T-cell non-Hodgkin lymphomas and classical Hodgkin lymphoma involved the breast at much lower frequency; most of these neoplasms involved the breast as part of disseminated disease. The clinical presentation correlated with radiologic findings: localized lymphomas presented as solitary masses, whereas disseminated lymphomas commonly presented as multifocal masses. There was a significant difference in the disease-free survival between patients with localized and disseminated DLBCL (P=0.003). In the disseminated group, patients with DLBCL had a worse disease-free survival compared with patients with mucosa-associated lymphoid tissue lymphoma or follicular lymphoma (P=0.01).     

B-cell posttransplant lymphoproliferative disorders in heart and/or lungs recipients: clinical and molecular-histogenetic study of 17 cases from a single institution

BACKGROUND: Posttransplantation lymphoproliferative disorders (PTLDs) are heterogeneous lymphoid proliferations representing a major complication of solid organ transplant. This study details the clinicopathological and molecular features of 17 B-cell PTLDs observed in a single center series of 988 heart and/or lung transplant recipients. METHODS: Cases were classified according to World Health Organization lymphoma classification and tested for Epstein-Barr Virus (EBV), clonality, histogenetic phenotypic (CD10, Bcl-6, MUM1, CD138), and genotypic (immunoglobulin and BCL-6 genes somatic hypermutation) markers. RESULTS: This series of 17 PTLDs included: two B-cell monoclonal polymorphic PTLDs and 15 B-cell monomorphic PTLDs (13 diffuse large B-cell lymphomas [DLBCL] and 2 Burkitt lymphomas [BL]). EBV was detected in 9/17 cases. A monoclonal immunoglobulin variable (IGV) genes rearrangement was documented in 17/17 cases; IGV somatic hypermutation was found in 88% of cases, indicating a prevalent origin from germinal center (GC)-experienced B cells. Using immunophenotypic markers, three histogenetic profiles were identified: a) CD10/bcl-6/MUM1/CD138, mimicking GC B-cells; b) CD10-/bcl-6+/MUM1+/CD138-, reminiscent of B-cells at the latest phases of GC reaction; and c) CD10-/bcl-6-/MUM1+/CD138+/-, consistent with preterminally differentiated B-cells. CONCLUSIONS: Correlation between morphology, histogenesis, and EBV status demonstrated a high degree of homogeneity in the two GC-related groups, mostly including EBV-negative cases with BL and DLBCL-centroblastic features; the third group, consisting of post GC EBV-positive cases, was histologically less homogeneous, as it included polymorphic PTLDs and DLBCL with immunoblastic and anaplastic features. The EBV-negative cases with GC histogenetic phenotype showed a slightly better outcome; however, such less aggressive prognostic trend was not confirmed by statistical analysis.     

BCL-2 is consistently expressed in hyperplastic marginal zones of the spleen,abdominal lymph nodes,and ileal lymphoid tissue

BCL-2 is an antiapoptotic protein overexpressed in follicular lymphomas, principally as a result of the t(14;18)(q32;q21), and useful in distinguishing follicular lymphoma (usually BCL-2 positive) from follicular hyperplasia (BCL-2 negative). BCL-2 is also overexpressed in other lymphoma types without the t(14;18), including marginal zone B-cell lymphoma, because of other, poorly understood mechanisms. It has been suggested that BCL-2 immunoreactivity can distinguish between malignant (BCL-2 positive) and reactive (BCL-2 negative) marginal zone B cells. In this study, we evaluated 26 spleen, 10 abdominal lymph node, and 3 ileum specimens with marginal zone B-cell hyperplasia for BCL-2 expression immunohistochemically. We also analyzed these cases using polymerase chain reaction methods to evaluate for the presence of clonal rearrangements of the immunoglobulin heavy chain gene (IgH) using consensus V FRIII and J region primers, and the t(14;18) involving both the major breakpoint and the minor cluster regions of the bcl-2 gene. All (100%) cases of splenic, abdominal lymph node, and ileal marginal zone hyperplasia displayed strong BCL-2 reactivity in the marginal zone B cells. In all cases analyzed, IgH polymerase chain reaction demonstrated a polyclonal pattern, and bcl-2/JH DNA fusion sequences were not detected. Our results indicate that BCL-2 is consistently expressed by reactive marginal zone B cells of the spleen, abdominal lymph nodes, and ileal lymphoid tissue and should not be used as a criterion for discriminating between benign and malignant marginal zone B-cell proliferations involving these sites.     

Follicular colonization in B-cell lymphoma of mucosa-associated lymphoid tissue

The formation of neoplastic B-cell follicles is universally accepted as diagnostic of a follicle centre cell (FCC) lymphoma. Low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) are characterized by a diffuse infiltrate of cells of uncertain lineage known as "centrocyte-like" cells because of their resemblance to centrocytes (small cleaved cells). Some MALT lymphomas, however, contain numerous follicles and may even have a predominantly follicular appearance. These follicles may be reactive or show immunoglobulin (Ig) light-chain restriction, indicating their neoplastic nature. We have proposed that these neoplastic follicles are not composed of follicle centre cells but result from colonization of reactive follicles by CCL cells. In this study, the immunophenotype and genotype of 10 primary gastrointestinal lymphomas with a follicular component have been determined. One case exhibited the morphological, immunophenotypic, and genotypic features of FCC lymphoma (Ig light-chain restriction, CD10+, KB61 (CDw32)-, Jh, and bcl-2 gene rearrangement). Neoplastic follicles in the remaining nine cases, which showed the features of MALT lymphoma, were of a different phenotype (Ig light-chain restriction, CD10- KB61(CDw32)+), and these lymphomas showed Jh but not bcl-2 gene rearrangement. Taken in conjunction with the morphological features, these findings suggest that in these cases the neoplastic follicles formed as the result of colonization of previously reactive follicles by neoplastic CCL cells. Thus, not all lymphomas containing neoplastic follicles are of FCC origin. Follicular colonization, as seen in low-grade MALT lymphomas, is likely to be a recapitulation of an as yet undescribed normal immunological phenomenon that may involve marginal zone B cells.     

Primary cutaneous CD4+ small/medium-sized pleomorphic T-cell lymphoma expresses follicular T-cell markers

Cutaneous CD4 small/medium-sized pleomorphic T-cell lymphoma (CSTCL) is a cutaneous T-cell lymphoma defined by a predominance of small-to-medium-sized CD4 pleomorphic T cells, with a favorable clinical course. Cases are also characterized by the presence of a rich infiltrate of reactive B cells. Recently, it has been reported that follicular helper T cells (TFH cells) display a distinct gene expression profile, positive for PD-1, CXCL13, and BCL-6. We report for the first time the expression of PD-1 and other TFH cell markers in CSTCLs and discuss its biologic significance. Sixteen CSTCLs were included in this study, and also 20 reactive inflammatory conditions, 10 primary cutaneous marginal zone, 10 follicular center lymphomas, and 5 primary CD30 cutaneous lymphomas. They were immunohistochemically analyzed for a large panel of markers. Double immunoperoxidase labeling of paraffin sections was performed for PD-1, OCT-2, and BCL-6. Clonal Ig and T-cell receptor rearrangements and Epstein-Barr virus-encoded RNA expression were also evaluated. Morphologic and clinical data were reviewed. Histologic examination showed a dense polymorphic lymphoid infiltrate throughout the dermis. Atypical large CD4 cells were positive for PD-1, CXCL13, and BCL-6 in all cases, and were attached in small clusters, or formed rosettes around CD30/OCT-2+ B blast cells. Epstein-Barr virus was not apparent in any of the cases. A dominant T-cell clone was identified in 14 cases, whereas polymerase chain reaction IgH gene rearrangement studies showed that all cases were polyclonal. None of the patients had lymphadenopathy or showed any evidence of systemic disease, nor did they have any previous history of mycosis fungoides or drug reactions. FTH cell markers are not exclusive to angioimmunoblastic lymphadenopathy but may also be seen in neoplastic cells of CSTCLs. Moreover, these findings suggest that B-cell stimulation by FTH could also take place in some cutaneous T-cell lymphomas.     

Clinicopathologic Features of B-Cell Lineage Neoplasms With Aberrant Expression of CD3: A Study of 21 Cases

CD3 expression by immunohistochemistry was historically considered restricted to T-lineage or NK-lineage neoplasms but recently has been reported in rare cases of mature B-cell neoplasms, frequently in association with Epstein-Barr virus. Here, we describe the pathologic features of 21 B-cell lineage neoplasms that express CD3 protein by immunohistochemistry: 12 diffuse large B-cell lymphomas (DLBCLs); 2 plasmablastic lymphomas (PBLs); 4 plasma cell neoplasms; 2 Burkitt lymphomas; and 1 nodal follicular lymphoma, grade 3A. CD20 expression was negative or only partially positive in 13/21 cases. Epstein-Barr virus was positive in 3/20 tested cases (2 PBLs and 1 DLBCL). All tested neoplasms (14/14) had clonal immunoglobulin gene rearrangements, and no clonal T-cell gene rearrangements were detected (0/14). The 12 DLBCLs segregated into 2 main groups: 7 demonstrated features of plasmacytic differentiation but did not meet criteria for PBL, and 5 had anaplastic features. In addition to morphology, other features shared among the DLBCLs with plasmacytic differentiation, the plasma cell neoplasms, and the PBLs included extranodal presentation, cytoplasmic localization of CD3, and lack of expression of other T-cell antigens in most cases. In contrast, DLBCLs with anaplastic features and the single follicular lymphoma coexpressed multiple T-cell antigens in a predominantly membranous pattern and presented with nodal disease in a relatively younger patient population. Our data expand the spectrum of morphologic, phenotypic, and clinical features of B-cell neoplasms aberrantly expressing CD3. As these neoplasms often lack typical expression of B-cell antigens, knowledge of these features will help avoid misclassification.     

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

Waldenstrom macroglobulinemia (WM) is a clinicopathologic syndrome in which a B-cell neoplasm involving the bone marrow, usually lymphoplasmacytic lymphoma (LPL), is associated with immunoglobulin M paraprotein in the serum. Extramedullary involvement occurs in a subset of patients and is infrequently examined histologically. The files of M.D. Anderson Cancer Center were searched for patients with WM who underwent biopsy of one or more extramedullary sites during the course of disease. Each biopsy specimen was classified using the criteria of the World Health Organization classification. The study group consisted of 44 patients (26 men and 18 women), with a total of 51 specimens obtained from lymph nodes (n = 36), soft tissue (n = 4), spleen (n = 3), skin (n = 2), lung (n = 2), tonsils (n = 1), colon (n = 1), liver (n = 1), and gallbladder (n = 1). Lymphoplasmacytic lymphoma was the most common histologic type, in 40 (78%) samples. This category was morphologically heterogeneous and was further subclassified as lymphoplasmacytic (n = 21), lymphoplasmacytoid (n = 18), and polymorphous (n = 1). Four of these LPL cases morphologically resembled marginal zone B-cell lymphoma. Four additional samples were involved by diffuse large B-cell lymphoma, probably transformed from LPL. Three more samples were involved by LPL with unusual features: two were CD5-positive and one was a composite tumor with classical Hodgkin's disease. Other categories of lymphoma in this group of patients with WM included small lymphocytic lymphoma/chronic lymphocytic leukemia (n = 2), mantle cell lymphoma (n = 1), and follicular lymphoma (n = 1). Waldenstrom macroglobulinemia is most commonly associated with LPL but can rarely occur with other types of B-cell lymphoma. Lymphoplasmacytic lymphoma in patients with WM is morphologically heterogeneous and can be indistinguishable from marginal zone B-cell lymphoma. CD5+ B-cell lymphomas with features otherwise typical of LPL are rare, and we think these tumors are part of the spectrum of LPL.     

Primary Diffuse Large B-Cell Lymphoma of the Oral Cavity: Germinal Center Classification

Primary lymphomas of the oral cavity are rare and the most frequent type is diffuse large B-cell lymphoma (DLBCL). Recently, several reports have highlighted the value of classifying DLBCL into prognostically important subgroups, namely germinal center B-cell like (GCB) and non-germinal center B-cell like (non-GCB) lymphomas based on gene expression profiles and by immunohistochemical expression of CD10, BCL6 and MUM-1. GCB lymphomas tend to exhibit a better prognosis than non-GCB lymphomas. Studies validating this classification have been done for DLBCL of the breast, CNS, testes and GI tract. Therefore we undertook this study to examine if primary oral DLBCLs reflect this trend. We identified 13 cases (age range 38–91 years) from our archives dating from 2003–09. IHC was performed using antibodies against germinal center markers (CD10, BCL6), activated B-cell markers (MUM1, BCL2) and Ki-67 (proliferation marker). Cases were sub-classified as GCB subgroup if CD10 and/or BCL6 were positive and MUM-1, was negative and as non-GCB subgroup if CD10 was negative and MUM-1 was positive. Immunoreactivity was noted in 2/13 cases for CD10, in 12/13 for BCL6, in 8/13 for MUM-1, and in 6/13 for BCL2. Therefore, 8/13 (58%) were sub-classified as non-GCB DLBCLs and 5/13 (42%) as GCB subgroup. All tumors showed frequent labeling with Ki-67 (range 40–95%). Four of the 8 patients with non-GCB subgroup succumbed to their disease, with the mean survival rate of 16 months. Two patients in this group are alive, one with no evidence of disease and another with disease. No information was available for the other 3 patients in this group. Four of the 5 patients in the GCB subgroup were alive with no evidence of disease and one patient succumbed to complications of therapy and recurrent disease after 18 months. In conclusion, our analysis shows that primary oral DLBCL predominantly belongs to the non-GCB subgroup, which tends to exhibit a poorer prognosis. These findings could allow pathologists to provide a more accurate insight into the potential aggressive behavior and poorer prognosis of these lymphomas.     

Extranodal marginal zone B-cell lymphomas of the ocular adnexa: multiparameter analysis of 34 cases including interphase molecular cytogenetics and PCR for Chlamydia psittaci

Extranodal marginal zone B-cell lymphomas of MALT type (MALT lymphomas) show site-dependent variations in their morphologic, phenotypic, and/or cytogenetic findings. This report describes a comprehensive analysis of 34 ocular adnexa MALT lymphomas, including interphase fluorescence in situ hybridization for MALT lymphoma-associated cytogenetic abnormalities and polymerase chain reaction for Chlamydia psittaci, which has recently been suggested to be associated with ocular adnexa lymphomas. A typical morphologic pattern was identified in 79% of cases, while overtly monocytoid cytology (12%), predominantly plasmacytic features (9%), and lymphoepithelial lesions (3%) were uncommon. Aberrant CD43 or CD5 expression was also uncommon (12% and 3%, respectively). Plasmacytic differentiation (41%) was associated with stage IV disease (P=0.036) and gains of chromosomes 3 and/or 18q (P=0.021) (79%). +3 was more frequent in the orbit than in lacrimal gland or conjunctiva (P=0.005). Each of 31 cases was negative for MALT1 translocations. IGH translocations were identified in 3 cases (10%), although the translocation partner gene could not be identified. Polymerase chain reaction assays targeting species-specific regions within the C. psittaci omp1 and omp2 genes were negative in each of 30 cases. This study identifies the characteristic morphologic, phenotypic, and cytogenetic findings in ocular adnexa MALT lymphoma, including a subset differing from those arising at other anatomic sites. The frequent presence of +3 and/or +18q suggests that these abnormalities may contribute to lymphomagenesis. The lack of C. psittaci in this series, in contrast to some prior reports, indicates that there may also be geographic heterogeneity in the pathogenesis of ocular adnexa MALT lymphoma.     

Clinicopathologic, immunophenotypic, and molecular cytogenetic fluorescence in situ hybridization analysis of primary and secondary cutaneous follicular lymphomas

Although primary cutaneous follicular lymphoma (FL) is considered a distinct variant of FL in the World Health Organization classification ("cutaneous follicle center lymphoma"), its biologic relationship to nodal FL remains controversial. The clinical, morphologic, immunophenotypic, and molecular cytogenetic features of 17 patients with primary cutaneous FL were studied and compared with 16 patients with secondary cutaneous FL. The head and neck region was the most frequent site at initial skin presentation in both the primary and secondary cases. Among the primary cases, 29% of the 31 biopsies were grade 1, 48% grade 2, 13% grade 3, and 10% grade 3 with diffuse large B-cell (DLBCL) areas. Among the secondary cases, 38% of the 29 skin biopsies were grade 1, 45% grade 2, 3% grade 3, and 7% grade 3 with DLBCL areas with two not evaluable. A floral-like pattern was observed in 32% of primary FL but only 5% of secondary cases. Histologic progression was found in 21% of patients. CD10 expression was demonstrated in 90% (27 of 30) of primary cases and 96% (22 of 23) of secondary cases. Bcl-6 was expressed in all cases tested. Bcl-2 expression was detected in 57% (17 of 30) of the primary cases (100% of grade 1, 43% of grade 2, 40% of grade 3), whereas all secondary cases were bcl-2 positive (P=0.0002). The t(14;18) translocation was identified by interphase fluorescence in situ hybridization (FISH) in biopsies from 31% (4 of 13) of the patients with primary FL compared with 77% (10 of 13) of those with secondary lymphoma (P <0.05). Seven of the 17 (41%) patients with primary disease had cutaneous relapse, including 1 who also developed nodal disease. Bcl-2 positivity was seen in 4 of these 7 patients. Eight of the 16 (50%) patients with secondary FL had cutaneous relapse. Primary and secondary cutaneous FL share many clinical and phenotypic features, but primary cases may have some distinctive morphologic features, more frequently lack bcl-2 protein, and often lack the t(14;18) translocation. These findings suggest that primary cutaneous FL are distinctive and often but not always have a pathogenesis different from most of nodal and secondary cutaneous FL.     

Incidental MALT Type Lymphoma Exhibiting Prominent Plasma Cell Differentiation Associated with Hashimoto’s Thyroiditis. A Two Case Report

We present here two cases of incidental extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma) showing prominent plasma cell differentiation associated with Hashimoto’s thyroiditis (HT). Histological examination demonstrated that both lesions exhibited HT including lymphoplasmacytic infiltration with the formation of germinal centers, destruction of the normal thyroid follicular architecture, Hürthle cell changes, and squamous metaplasia. The dominant tumor nodules of both cases contained large, well-circumscribed but unencapsulated aggregation of mature plasma cells and scattered centrocyte-like cells (CCL-cells). Both lesions contained a few lymphoepithelial lesions. Moreover, immunohistochemical study demonstrated that plasma cells and CCL-cells of these two lesions contained monotypic intracytoplasmic kappa light chain. Other small B-cell lymphomas, plasmacytoma and plasmablastic lymphoma were excluded using stains for CD5, CD10, CD23, CD43, CD56. Cyclin D1, human herpes virus type-8.