Chronic lymphocytic leukaemia: one disease or two?

The discovery that the presence or absence of somatic mutations in immunoglobulin variable region genes separates chronic lymphocytic leukaemia (CLL) into benign and malignant subsets has raised the question as to whether CLL is one disease or two. Although there are similarities between morphology, immunophenotype and gene expression profiles between the two subsets, the very different natural histories and the immutability of one to the other suggests two diseases deriving from a common stem. It is proposed that a single intrinsic defect of B-lymphocytes dictates a particular reaction pattern -- partially activated, anergic and anti-apoptotic -- when the B-cell receptor is stimulated. The difference between the two subsets is determined by whether the receptor is stimulated conventionally within the germinal centre or unconventionally, outside it. The further differences, including CD38 expression and chromosomal abnormalities, are the consequences of further ongoing stimulation of the receptor leading to low-grade proliferation.

Lack of somatic hypermutation of IG V(H) genes in lymphoid malignancies with t(2;14)(p13;q32) translocation involving the BCL11A gene

The t(2;14)(p13;q32.3) involving the BCL11A and IGH genes is a rare but recurrent chromosomal aberration in B-cell malignancies. Hitherto, juxtaposition of BCL11A and IGH has only been described in B-cell chronic lymphocytic leukemia (B-CLL) and immunocytoma. As subgroups of B-CLL can be distinguished by the pattern of somatic mutation of immunoglobulin variable (V) genes we investigated four lymphomas with IGH/BCL11A involvement for IGH hypermutation. Clonal V(H) gene rearrangements were amplified; in all four cases, sequencing of the amplificates revealed the rearranged V(H) genes to lack somatic mutations. These results suggest that t(2;14)(p13;q32.3) is associated with a subset of B-CLL/immunocytoma characterized by non-mutated IG genes deriving from pre-germinal center B cells. As the translocations in both informative cases are targeted to the switch regions of the IGG2 gene, which is mainly used in T cell-independent immune responses, these translocations presumably occurred in activated B cells in the course of T cell-independent immune responses outside the germinal center.

Somatically mutated Ig V(H)3-21 genes characterize a new subset of chronic lymphocytic leukemia

Recent studies on the immunoglobulin variable heavy chain (IgV(H)) genes have revealed that B-cell chronic lymphocytic leukemia (B-CLL) consists of at least 2 clinical entities with either somatically mutated or unmutated V(H) genes. We have analyzed the V(H) gene mutation status and V(H) gene usage in 119 B-CLL cases and correlated them to overall survival. A novel finding was the preferential use of the V(H)3-21 gene in mutated cases, whereas biased V(H)1-69 gene usage was found in unmutated cases as previously reported. Interestingly, the subset of mutated cases using the V(H)3-21 gene displayed distinctive genotypic/phenotypic characteristics with shorter average length of the complementarity determining region 3 and clonal expression of lambda light chains. In addition, this mutated subset showed significantly shorter survival than other mutated cases and a similar clinical course to unmutated cases. We therefore suggest that B-CLL cases with mutated V(H)3-21 genes may constitute an additional entity of B-CLL.

Fine-needle aspiration biopsy of anaplastic large cell lymphoma, small cell variant with prominent plasmacytoid features: case report

Anaplastic large cell lymphoma (ALCL), according to the new WHO classification, is a diagnosis limited to T/NK cell lymphomas. We present a case that demonstrates a new morphologic variant of ALCL with significant possible pitfalls for the cytopathologist. A fine-needle aspiration biopsy of a cervical lymph node showed a cellular aspiration comprised of medium-sized plasmacytoid cells in a discohesive and focally loosely cohesive pattern. The cytologic diagnosis confirmed the presence of malignancy and noted the prominent plasmacytoid features. An accompanying comment favored melanoma and included a broad differential. No cell block was available for immunohistochemical stains. Immunophenotyping of the subsequent excisional node biopsy showed an anaplastic lymphoma kinase (ALK)-positive ALCL. This case illustrates a new variant of ALCL. Although ALCL variants, such as small cell and lymphohistiocytic, are well recognized, the plasmacytoid features are an additional potential source for misdiagnosis. This case report shows that a cytopathologist should include ALK-positive ALCL in the differential diagnosis of plasmacytoid proliferations cell because of the clinical importance of the ALK-positive ALCL.

Advances in classification and therapy of indolent B-cell malignancies

Advances in our understanding of normal B-cell differentiation have allowed for improved classification and therapy of B-cell malignancies. B-cell neoplastic diseases may be classified more accurately according to the differentiation stages of presumed normal B-cell counterparts. These advances have challenged the notion that chronic lymphocytic leukemia represents a malignancy of naive CD5 B cells. Analyses of immunoglobulin genes and gene expression patterns through microarray have defined at least two types of chronic lymphocytic leukemia that differ in their tendency toward disease progression. Nevertheless, these types still share more in common than they do with other lymphoid malignancies, and both may be derived from memory-type B cells. Advances in immune therapy are revolutionizing the approach to therapy. B-cell surface differentiation antigens constitute tissue-specific targets for passive immune therapy. Since the US Food and Drug Administration approval of rituximab (Rituxan; Genentech, Inc, South San Francisco, CA, and IDEC Pharmaceuticals, San Diego, CA) for use in the treatment of follicular lymphoma, monoclonal antibody therapy is being considered for all types of B-cell malignancies. The ability to transform leukemia and lymphoma B cells into effective antigen-presenting cells through CD40 ligation allows for autologous immune recognition of neoplastic cells. Together, active and passive immune approaches have potential for effective treatment of patients with these diseases.

P2X7 receptor expression in evolutive and indolent forms of chronic B lymphocytic leukemia

Human leukocytes express a receptor for extracellular nucleotides, named P2X7R, that in lymphocytes can either mediate cell death or proliferation, depending on the level of activation. The authors have investigated P2X7R expression and function in 21 patients affected by B-cell chronic lymphocytic leukemia, 13 with an evolutive and 8 with an indolent variant of the disease. Resting cytoplasmic Ca++ concentration was significantly higher in lymphocytes from patients with the evolutive compared with indolent variant. Furthermore, in the former, P2X7R stimulation triggered a Ca++ influx significantly larger. Higher Ca++ influx correlated with an increased P2X7R expression in the lymphocytes from patients with the evolutive form. Finally, incubation in the presence of extracellular adenosine triphosphate decreased spontaneous proliferation of lymphocytes from patients affected with the evolutive variant but had no effects on lymphocytes from patients with the indolent form. These results suggest that expression and function of P2X7R may correlate with the severity of B-cell chronic lymphocytic leukemia.

Use of novel t(11;14) and t(14;18) dual-fusion fluorescence in situ hybridization probes in the differential diagnosis of lymphomas of small lymphocytes

Increasingly, molecular biologic techniques have become important in the diagnosis of non-Hodgkin lymphomas. In the differential diagnosis of lymphoma(s) of small lymphocytes (LSL), reliable detection of t(11;14) or t(14;18) would confirm the diagnosis of mantle cell lymphoma (MCL) or follicle center lymphoma (FCL), respectively. A total of 87 LSL cases (27 MCL, 39 FCL, 17 small lymphocytic lymphoma [SLL], 3 marginal zone lymphomas, and 1 paraimmunoblastic variant of SLL) were diagnosed by a combination of light microscopy, immunohistochemistry, and flow cytometric immunophenotyping. Interphase fluorescence in situ hybridization (FISH) for t(11;14) and t( 14;18) using dual-fusion probes (Vysis, Downers Grove, IL) was performed on touch (n = 69) or gravity (n = 18) preparations from these cases. Of 27 MCL cases tested, 25 (93%) had demonstrable t(11;14), none had t(14;18), and 2 were negative for t(11;14) and t(14;18). Twenty-five of 39 (64%) FCL cases had t(14;18), none had t(11;14), and the remaining FCL cases (14 cases [35%]) had neither t(11;14) nor t(14;18). All 17 (100%) SLL cases had neither t(11;14) nor t(14;18). All 3 (100%) marginal zone lymphoma cases had neither t(11;14) nor t(14;18). The case of paraimmunoblastic variant of SLL had t(11;14) and was negative for t(14;18). No discrepant [i.e., positive for both t(11;14) and t(14;18)] or false-positive cases were noted. Interphase FISH using these commercially available probes is a useful adjunct to light microscopy, immunohistochemistry, and flow cytometric immunophenotyping in the diagnosis of LSL. FISH can be performed successfully on archival single-cell preparations (touch preparations or gravity preparations) when fresh tissue is unavailable. No discordant or false-positive cases were identified.

A multicentric study of 41 cases of B-prolymphocytic leukemia: two evolutive forms

B-prolymphocytic leukemia (B-PLL) is an infrequent disease with a poor prognosis. We present the clinical and biological features of 41 patients. Median age was 67 years [42-89] and male-female sex ratio was 2.4. The immunophenotyping revealed B-cell phenotype, with a high level expression of surface IgM and/or IgD in all cases, FMC7+ in 76 % of cases and CD5+ in 67%. Marked spontaneous in-vitro apoptosis was observed in most cases tested (n = 12). The median overall survival time was 5 years and the event-free survival time was 37 months. As detected by univariate and multivariate analysis, the only variables associated with a poor prognosis were advanced age and anemia. No significant difference was observed between de novo PLL (n = 27) and prolymphocytoid transformation of chronic lymphocytic leukemia (n = 14). Two groups of patients were individualized according to their clinical course: patients who died within one year of diagnosis (n = 14) and patients who had a prolonged survival (n = 23) without any treatment in some cases. The comparison between the 2 groups showed that they differed in age (p = 0.01) and anemia (p = 0.02). We also observed that the patients with p53 mutations had a worse clinical outcome. Taken together these data confirm that B-PLL should be regarded as a distinct form of chronic lymphoproliferative disorder and suggest the existence of two patterns of clinical evolution.

Chronic lymphocytic leukemia incidence is substantially higher than estimated from tumor registry data

BACKGROUND

Although chronic lymphocytic leukemia (CLL) often is described as the most common leukemia in the U.S. and Western Europe, to the authors' knowledge the true incidence of CLL in the U.S. is unknown. CLL incidence is estimated from tumor registry reports based on tissue pathology and cancer treatment data. Tumor registry data may underestimate the incidence of CLL substantially because CLL can be diagnosed by flow cytometric analysis of peripheral blood cells, and the majority of patients do not require treatment at the time of diagnosis.

METHODS

To test the hypothesis that CLL has a higher incidence than estimated from tumor registry data, the authors compared the actual and reported incidence of CLL for a 10-year interval at the Central Arkansas Veterans Healthcare System (CAVHS). The accuracy of surveillance methods for new diagnoses of CLL was confirmed by reviewing the lymphocyte counts in 45,009 CAVHS patients over a 4-year period.

RESULTS

The tumor registry correctly reported 58 of 93 patients with CLL (62.4%) who were diagnosed between January 1, 1990 and December 31, 1999. The tumor registry correctly reported 100% of patients with CLL diagnosed between 1990-1991 but reported only 34.5% of patients with CLL diagnosed between 1998-1999.

CONCLUSIONS

The incidence of CLL in the CAVHS was 37.6% higher than estimated from tumor registry data due to an increase in the use of peripheral blood immunophenotype as the only diagnostic test for CLL over the time period of the study. These data suggest that the true incidence of CLL may be substantially higher than estimated from tumor registry data.

Reference values for peripheral blood B-lymphocyte subpopulations: a basis for multiparametric immunophenotyping of abnormal lymphocytes

BACKGROUND AND OBJECTIVES

Immunophenotyping has become a useful tool for the differential diagnosis of chronic B-cell lymphoproliferative disorders. The aim of this work was to determine reference values of normal B-cell subpopulations.

MATERIAL AND METHODS

Blood samples from 38 healthy volunteers were analyzed by multidimensional flow cytometry, using a panel of directly conjugated antibodies. Results were expressed as percent of positive B cells and as median fluorescence intensity, an indirect assessment of the expression level.

RESULTS

CD20, CD22, CD24, CD40, CD79a, CD79b, FMC7, CD11a, CD18, CD44 were positive in the whole B cell population, whereas CD10, CD86, CD103, CD154 and FasL were almost absent from the B-lymphocyte population. 75% were IgD positive. The kappa/lambda ratio was 1.5. CD5, CD23, CD25, CD38, CD43, CD54, CD62L, CD80 and CD95 were positive in different B-cell subpopulations. The utility of all these markers in the differential diagnosis of chronic B-cell lymphoproliferative disorders is discussed.

CONCLUSION

In order to interpret a pathological immunophenotype, it is necessary to refer to quantitative and qualitative values of normal B-cell subpopulations.

Is lymphoplasmacytic lymphoma/immunocytoma a distinct entity? A clinicopathologic study of 20 cases

Lymphoplasmacytic lymphoma/immunocytoma (LLI) was defined initially as a small B-cell lymphoma with plasmacytoid or plasmacytic features. Because other types of small B-cell lymphoma, particularly marginal zone B-cell lymphoma may exhibit plasmacytic differentiation, the revised European-American lymphoma classification and World Health Organization has defined LLI more narrowly to exclude other small B-cell lymphomas. The goal of this study was to reevaluate LLI as a clinicopathologic entity. Twenty cases were selected from 43 previously diagnosed as "small lymphocytic lymphoma, plasmacytoid" or "immunocytoma" from 1985 to 1998. Cases fulfilling the criteria for B-cell small lymphocytic lymphoma, follicular lymphoma, marginal zone B-cell lymphoma, or other types of B-cell lymphoma were excluded. The histopathology and immunoreactivity for CD20, CD79a, CD3, CD43, CD23, CD5, kappa, lambda, and immunoglobulins (Ig's) M, G, and A were reviewed, in addition to available clinical findings. There were 13 men and seven women, with a mean age of 69 years. Five patients had documented Waldenström's macroglobulinemia (WM). Three architectural patterns were observed. Pattern A (seven of 20) showed open sinuses, small follicles, and hemosiderosis; pattern B (four of 20) showed hyperplastic follicles; and pattern C (nine of 20) showed diffuse effacement. Epithelioid histiocytes were prominent in patterns B and C but absent in A. Cytologically, six of 20 were polymorphous with 10% to 40% transformed cells; 14 of 20 were lymphoplasmacytic. Five cases showed minor foci of monocytoid B cells. One case showed a composite histology of LLI and small lymphocytic lymphoma. Amyloid was present in two cases. All cases were CD20 and/or CD79a immunoreactive, with two of 20 positive for CD43. Twelve cases were kappa monoclonal and eight cases were lambda monoclonal. Twelve of 17 cases that could be evaluated were positive for IgM and five were positive for IgG. All cases were negative for CD5 and CD23 with the exception of the one case with a composite histology. Eleven of 20 patients with available follow-up died of disease (median, 48 months), and eight of 20 are alive with disease at a follow-up of 6 months to 2 years. LLI does appear to represent a distinct clinicopathologic entity even though it shows morphologic heterogeneity and overlapping features with marginal zone B-cell lymphoma and small lymphocytic lymphoma. Recognition of LLI is important because the overall prognosis may be worse than for other types of small B-cell lymphomas.

Extranodal lymphoplasmacytoid lymphoma (immunocytoma) presenting as small intestinal obstruction

A 57-year-old woman presented with intermittent symptoms of intestinal obstruction. Workup provided nondiagnostic radiologic studies. An exploratory laparotomy revealed a segmental dilatation in the proximal ileum, which showed diffuse thickening of the intestinal wall. Microscopic examination of the affected area disclosed a diffuse transmural infiltrate composed of small lymphocytes, mature plasma cells, and lymphoplasmacytoid cells in different stages of maturation associated with extracellular periodic acid-Schiff-positive material. In addition, serum protein electrophoresis showed a monoclonal immunoglobulin M kappa paraprotein. Postoperative workup did not demonstrate evidence of systemic involvement. The morphologic features and immunohistochemical and molecular analyses were consistent with lymphoplasmacytoid lymphoma (immunocytoma). We report an unusual case of primary extranodal immunocytoma involving the small intestine and discuss its clinicopathologic features.

Cytology and immunophenotyping of low- and intermediate-grade B-cell non-Hodgkin's lymphomas with a predominant small-cell component: a study of 56 cases

Diagnosis of non-Hodgkin's lymphomas based on cytologic evaluation of fine-needle aspirates and body cavity fluids has gained increasing acceptance. However, the accurate diagnosis and classification of low- and intermediate-grade B-cell lymphomas with a predominant small-cell population still present a diagnostic challenge. In this study, we reviewed the cytology and immunophenotype of 56 cases of low- and intermediate-grade non-Hodgkin's B-cell lymphomas composed of predominantly small cells, with histologic correlation in all cases. These cases consisted of 23 small lymphocytic lymphomas (SLL), 15 follicular center lymphomas (FCL), grade I (small cell predominant), 8 lymphoplasmacytoid lymphomas (LPL), 6 mantle-cell lymphomas (MCL), and 4 marginal zone lymphomas (MZL) including mucosa-associated lymphoid tissue (MALT) lymphoma. Histologic comparison was available in all cases. A cytologic diagnosis of malignant lymphoma was made in 46 (82%) cases. Based on cytomorphology and immunophenotyping of cytologic material, 39 (85%) cases were correctly classified using the Revised European and American Lymphoma classification. In 7 (11%) cases, which included 3 FCLs, 2 MALT lymphomas, and 2 SLLs, the findings were atypical but not diagnostic of lymphoma. There were 3 (5%) false-negative cases. They were 2 SLLs and a FCL. Immunophenotyping done in 4 "atypical" cases was noncontributory. No marker studies were done in the remaining "atypical" case and all false-negative cases. We conclude that cytology, when used in conjunction with immunophenotyping, can accurately diagnose and in most instances subclassify low- and intermediate-grade B-cell non-Hodgkin's lymphoma with a predominant small-cell population.

Small lymphocytic lymphoma with perifollicular, marginal zone, or interfollicular distribution

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) typically involves nodal or extranodal tissues as a diffuse proliferation with pseudofollicular growth centers obliterating normal architecture. We describe 16 cases of CLL/SLL in which the neoplasm was confined to the marginal zone, perifollicular, or interfollicular regions surrounding benign lymphoid follicles in either nodal or extranodal sites. Twelve of 12 (100%) patients with adequate staging data had disseminated disease (Stage III or IV) at presentation. Eight of the 16 (50%) patients had absolute peripheral lymphocytosis (range, 5 to 30 x 10(9)/L). Pseudofollicular growth centers were identified in 14 of 16 cases (87.5%). Immunophenotypic studies revealed that the tumor cells were positive for CD20 (16/16) and CD5 (11/11) in all cases examined. CD23 was positive in 12 of 14 (86%) interpretable cases. IgM and IgD were positive in 13 of 14 (93%) and 10 of 10 (100%) interpretable cases, respectively. All cases were negative for CD3 (16/16), CD45RO (16/16), CD10 (15/15), and cyclin D1 (15/15). We conclude that CLL/SLL can have unusual patterns of involvement, including marginal zone, perifollicular, and interfollicular patterns that can be difficult to recognize histologically. Thirteen of 16 (81%) cases in this study were misinterpreted by the referring pathologists. Recognition of proliferation centers coupled with demonstration of a CD5+ CD23+ B-cell immunophenotype establishes the correct diagnosis of CLL/SLL.

A novel variant of B-lymphoid leukemia expressing kappa/lambda light chains

We studied a patient with an indolent leukemia which behaved similarly to chronic lymphocytic leukemia (CLL). Leukemic cells, however, showed larger cell diameters and lower nuclear/cytoplasmic ratios than typical CLL cells, and contained numerous cytoplasmic vacuoles. The cells also demonstrated some morphologic characteristics of hairy cell leukemia. Furthermore, flow-cytometric analysis demonstrated a distinct population of kappa/lambda double-positive tumor cells, as well as kappa single and lambda single populations. Southern blot analysis confirmed rearranged bands for both light chains with a monoclonal heavy chain rearrangement. Despite a decision not to treat this asymptomatic patient, disease progression was not observed. This case may represent a unique variant of B lymphoid leukemia. Possible mechanisms of abnormal light chain expression are discussed.

Small B-cell lymphoproliferative disorders: an overview of diagnostic approach

Despite their common origin from the B-cell mature lymphoid system, small B-cell lymphomas/leukaemias represent in fact an heterogeneous group of diseases. Recent advances in immunohistochemistry and molecular techniques have improved our knowledge of the immune system and lymphoid neoplasms. An international consensus has been recently reached among pathologists and clinicians, that recognises clinico-pathological entities which are defined by a combination of morphological, immunophenotypical, genetic and clinical features. In each entity, a range of histological grade and clinical aggressiveness can be encountered. Recognition of these entities, combined with clinical prognostic factors has clinical implications in terms of response to treatment and prognosis. The purpose of this paper is to focus on a practical approach, either clinical or pathological, of the diagnosis of small B-cell lymphoma/leukaemia.

Usefulness of CD79b expression in the diagnosis of B-cell chronic lymphoproliferative disorders

We evaluated anti-CD79b for its usefulness in the diagnosis of B-cell chronic lymphoproliferative disorders (BCLPDs), particularly chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). We analyzed 100 BCLPDs for CD5, CD19, CD20, CD23, CD79b, and surface immunoglobulin light chain (sIg) expression by 4-color flow cytometry. CD20, CD79b, and sIg expression were quantified. Correlational analysis and univariable and multivariable logistic regression models were used to determine the best combination of antigens for the immunophenotypic classification of CLL vs other BCLPDs. Positive and statistically significant Spearman pairwise correlations between CD20, CD79b, and sIg fluorescence intensity were demonstrated. In the simplest models in which a single variable was considered, cutoff points were chosen that gave misclassification rates for CLL of 16% for CD79b, 19% for sIg, and 18% for CD20. Low-intensity CD79b, CD20, and sIg are associated highly with CLL. A panel containing CD5, CD19, CD23, and sIg allowed correct classification of most cases. Addition of CD20 or CD79b improved diagnostic accuracy; CD79b was slightly better than CD20. CD79b seems to be a useful addition to a standard flow cytometry panel for the evaluation of BCLPDs.

Somatic mutation of bcl-6 genes can occur in the absence of V(H) mutations in chronic lymphocytic leukemia

Somatic mutation in immunoglobulin variable (V) region genes occurs largely in the germinal center and, after neoplastic transformation, imprints V genes of B-cell tumors with the mutational history of the cell of origin. Recently, it has been found that chronic lymphocytic leukemia (CLL) consists of 2 subsets, each with a different clinical course, one with unmutated V(H) genes consistent with a naive B cell, and the other with mutated V(H) genes consistent with transit through the germinal center. However, somatic mutation also occurs at another distinct locus, the 5' noncoding region of the bcl-6 gene, in both B-cell tumors and in normal germinal center B cells. To probe the suggestive link between the occurrence of mutations in V(H) and bcl-6 genes, we analyzed the nature of somatic mutation at these distinct loci in the 2 CLL subsets. Unexpectedly, we found no such link in the CLLs defined by unmutated V(H) genes, with 4 of 10 cases clearly showing mutations in bcl-6. In those CLLs defined by somatically mutated V(H) genes, 4 of 9 cases predictively showed bcl-6 mutations. The frequency of bcl-6 mutations was comparable in both subsets, with mutations being biallelic, and in 3 of 8 cases indicative of clonal origins. Surprisingly, intraclonal variation, which is not a feature of V(H) genes in CLL, was found in 6 of 8 cases in both subsets. These data indicate that somatic mutation of the V(H) and bcl-6 loci may not necessarily occur in tandem in CLL, suggesting diverse pathways operating on the 2 genes.

Differences in IgE isotype switching induced by anti-CD40 monoclonal antibody and cytokines among subtypes of chronic B lymphoid leukemias

OBJECTIVE

Immunologic differences among the chronic B lymphoid leukemias defined by the French-American-British (FAB) classification were evaluated with respect to IgE isotype switching induced by anti-CD40 monoclonal antibody (mAb) and cytokines.

MATERIALS AND METHODS

We immunocytochemically studied IgE isotype switching of leukemic B cells from 25 cases and three cell lines established from the leukemias after stimulation with anti-CD40 mAb, plus each of the following cytokines: interleukin 2 (IL-2); IL-4; IL-10; tumor necrosis factor alpha (TNF-alpha); and transforming growth factor beta (TGF-beta). Also, genomic Cepsilon and Cepsilon transcripts were analyzed by polymerase chain reaction and reverse transcriptase polymerase chain reaction.

RESULTS

Leukemic cells from hairy cell leukemia variant and its cell line, with deletion of the Cepsilon gene, did not undergo IgE isotype switching in response to any of the stimuli. In contrast, a cell line (FH-5) established from chronic lymphocytic leukemia cells, bearing the Cepsilon gene, underwent the highest level of IgE isotype switching on stimulation with anti-CD40 mAb and IL-4. This response was correlated with the production of Cepsilon transcripts. IL-4, IL-10, and TNF-alpha induced higher levels of IgE isotype switching than the others. No IgE isotype switching was observed in any of the non-Hodgkin's lymphomas examined, except mantle cell lymphoma and lymphoplasmacytic lymphoma. Percentages of CD40(+) cells in five cases with follicular lymphoma were significantly lower than the other leukemias.

CONCLUSIONS

IgE isotype switching induced by anti-CD40 mAb with cytokines other than IL-4 was first demonstrated, whereas none of the non-Hodgkin's lymphomas except mantle cell lymphoma and lymphoplasmacytic lymphoma showed IgE isotype switching in response to any of the stimuli. Cells of follicular lymphoma were suggested to be different from cells of the other leukemias.

Identification of three subgroups of B cell chronic lymphocytic leukemia based upon mutations of BCL-6 and IgV genes

Although B cell chronic lymphocytic leukemia (B-CLL) has been traditionally viewed as a tumor of virgin B cells, this notion has been recently questioned by data suggesting that a fraction of B-CLL derives from antigen experienced B cells. In order to further clarify the histogenetic derivation of this lymphoproliferation, we have analyzed the DNA sequences of the 5' non-coding region of BCL-6 proto-oncogene in 28 cases of B-CLL. Mutations of BCL-6 proto-oncogene, a zinc finger transcription factor implicated in lymphoma development, represent a histogenetic marker of B cell transit through the germinal center (GC) and occur frequently in B cell malignancies derived from GC or post-GC B cells. For comparison, the same tumor panel was analyzed for somatic mutations of the rearranged immunoglobulin variable (IgV) genes, which are known to be acquired at the time of B cell transit through the GC. Sequence analyses of BCL-6 and IgV genes allowed the definition of three groups of B-CLL. Group I B-CLL displayed mutations of both BCL-6 and IgV genes (10/28; 36%). Group II B-CLL displayed mutated IgV genes, but a germline BCL-6 gene (5/28; 18%). Finally, group III B-CLL included the remaining cases (13/28; 46%) that were characterized by the absence of somatic mutations of both BCL-6 and IgV genes. Overall, the distribution of BCL-6 and IgV mutations in B-CLL reinforce the notion that this leukemia is histogenetically heterogeneous and that a substantial subgroup of these lymphoproliferations derives from post-germinal center B cells.

Non-Hodgkin's lymphoma involving the vagina: a clinicopathologic analysis of 14 patients

Non-Hodgkin's lymphomas (NHL) uncommonly involve the vagina. In this study, 14 NHL involving the vagina are reported. Eight cases were stage IE or IIE and are presumed to be primary. The mean age of these eight patients at presentation was 42 years (range, 26-66 yrs), and four of eight patients complained primarily of vaginal bleeding. Histologically, all eight neoplasms were diffuse large B-cell lymphoma (DLBCL). Clinical follow up ranged from 1.8 to 18 years. Six of eight patients were alive without evidence of disease at the last follow up (range, 2.8-21 yrs), one patient died of unrelated causes at 9 years, and one patient died from NHL at 1.8 years. In six patients vaginal involvement was part of systemic disease at diagnosis, either stage IIIE or IV. The mean patient age at the time vaginal involvement was detected was 65 years (range, 49-82 yrs). Four of six patients had vaginal bleeding. Five neoplasms were DLBCL and one tumor was B-cell small lymphocytic lymphoma/chronic lymphocytic leukemia. Clinical follow up for these patients ranged from 2 weeks to 13 years. Two patients were free of disease after treatment at 4.5 and 13 years, two patients were alive with progressive NHL, one patient died of NHL, and one patient was recently diagnosed. The authors conclude that low-stage (presumably primary) vaginal NHL are DLBCL, tend to occur in younger women, and cause vaginal bleeding. High-stage NHL involving the vagina are usually DLBCL, tend to affect older women, and are relatively more heterogeneous clinically and histologically, but also usually cause vaginal bleeding.

Classification of small B-cell lymphoid neoplasms using a paraffin section immunohistochemical panel

Immunophenotypic analysis is critical in categorizing small B-cell neoplasms; however, many recommended antibody panels have required fresh or frozen tissue. Many paraffin-reactive antibodies are now available but have been studied mostly in isolation. Therefore, the utility of a panel of paraffin-reactive antibodies in differentiating small B-cell neoplasms was investigated. Paraffin-embedded sections of small lymphocytic lymphoma/B-chronic lymphocytic leukemia (SLL/B-CLL; 12), mantle cell (MCL; 15), follicular (FL; 11), and marginal zone B-cell (MZL; eight) lymphomas were stained with CD20/L26, CD3, CD43/DF-T1 or Leu22, CD5/4C7, CD23/BU38, cyclin D1/H295, and CD10/56C6 antibodies. For select antibodies, results were compared to flow cytometric data (FC). Formalin and B5 fixation were also compared. Seven of 11 SLL/B-CLL were CD43+ CD5+ CD23+ cyclin D1- CD10-; seven of 11 MCL were CD43+ CD5+ CD23- cyclin D1+ CD10-; nine of 10 FL were CD43- CD5- CD23- cyclin D1- CD10+; and five of six MZL were CD43+ CD5- CD23- cyclin D1- CD10-. CD5, CD23, and CD10 stains showed sensitivities of 81, 88, and 100%, respectively, compared to FC. With B5 fixation, cyclin D1 was more often negative and CD5 more often equivocal. A panel of paraffin-reactive antibodies aids in classification of small B-cell neoplasms, although a small number of cases have indeterminate phenotypes and MZL have no defining features. CD5 separates most SLL/B-CLL and MCL from FL and MZL. CD23 separates SLL/B-CLL from most MCL, but cyclin D1 is most important for identifying MCL. CD10 positivity distinguishes most FL from other small B-cell lymphoid neoplasms.

[Small cell B-cell lymphomas: guidelines for differential diagnosis]

Similar to the R.E.A.L-System, the small cell B-cell lymphomas of the new WHO classification consist of chronic lymphocytic leukaemia of B cell type, mantle cell lymphoma, follicular lymphoma, lymphoplasmocytic lymphoma/immunocytoma, hairy cell leukaemia, as well as plasmacytoma. The only major difference between the WHO- and the REAL-classification is the consideration of prolymphocytic leukaemia as a single disease entity in the former system. All the above-mentioned lymphomas arise from B cells of varying stages of differentiation and, therefore, often demonstrate architectural, cytological and immunophenotypic characteristics of their normal physiological counterparts. Consideration of tumour cell growth pattern, -cytology, -immunophenotype and -growth fraction, together with the presence and consistency of the reactive cell infiltrate, usually leads to categorisation of a lymphoma in the majority of cases. The molecular biological characteristics of follicular lymphoma and mantle cell lymphoma are the best defined of the small cell B-cell lymphomas. Chromosomal translocations involving the immunoglobulin heavy chain genes and the bcl-2 gene or Cyclin D1 gene, respectively, probably belong to the initial changes in a cell, which, together with several subsequent unidentified genetic alterations, lead to the development of these tumours. Although nodal small cell B-cell lymphomas are usually diagnosed at an advanced stage of the disease, the progression of the disease--with the exception of mantle cell lymphomas--is often indolent. As a result, the small cell B-cell lymphomas were previously considered as "low-grade" Non-Hodgkin lymphomas in the Kiel classification. However, since the progress of a lymphoma subtype can be heterogeneous and since mantle cell lymphomas cannot really be considered as "low-grade" tumours, "umbrella grading" of lymphomas has been discarded in the WHO classification, with emphasis being placed on grading within a lymphoma disease entity. In the following pages, the characteristics important for the diagnosis and categorisation of the small cell B-cell lymphomas will be summarised. Further, we present information regarding the molecular biological and clinical characteristics of these lymphomas.