Diffuse low-grade B-cell lymphomas. Four clinically distinct subtypes defined by a combination of morphologic and immunophenotypic features

Expression of activation markers CD23 and CD69 in B-cell non-Hodgkin's lymphoma

The activation associated proteins CD23 and CD69 are expressed on cells of different lineages upon mitogenic stimulation. CD23 is a well characterized multifunctional protein in lymphocyte development recognized as a diagnostic marker for chronic lymphocytic leukaemia. CD69 is one of the earliest markers expressed after activation of T cells, but its function is unclear. The aim of this study was to investigate the expression of these antigens in B-cell non-Hodgkin's lymphomas (NHL) in relation to clinical behaviour. Ninety samples from 84 patients with NHL of B cell type were studied for the expression of CD23 and CD69 in CD20+ B cells by flow cytometric dual parameter analysis. In individual lymphomas the CD23 and CD69 antigens showed an "on or off" pattern with most or very few cells positive for each antigen. The CD23 antigen was expressed in 23 of 53 (43%) indolent lymphomas and in 2 of 37 (5%) aggressive cases. Most indolent lymphomas (81%) and about half the aggressive cases (53%) expressed the CD69 antigen. Thus, both markers were associated with indolent type. CD23 expression correlated with chronic lymphocytic leukaemia subtype and CD69 expression with male gender, advanced stage, newly diagnosed lymphoma and shorter survival.

Lack of Intraclonal Diversification in Ig Heavy and Light Chain V Region Genes Expressed by CD5+IgM+ Chronic Lymphocytic Leukemia B Cells: A Multiple Time Point Analysis

To analyze the modalities of clonal expansion of chronic lymphocytic leukemia (CLL) cells, we sequenced at multiple time points the V(D)J genes expressed by CD5+IgM+CLL B cells in three patients. All three V(D)J gene sequences were found to be point mutated. The mutation frequency in the Ig VH (3.96 × 10−2 and 2.41 × 10−2 change/bp) and Vκ and Vλ (6.67 × 10−2 and 1.74 × 10−2 change/bp) genes of two CLLs (1.19 and 1.32, respectively) was similar, and higher than that in the corresponding gene segments of the third CLL (1.69; 3.4 × 10−3 and 6.67 × 10−3 change/bp). In all three CLLs, there was no preferential representation of nucleotide changes yielding amino acid replacement (R mutations), nor was there any preferential segregation of R mutations within the Ig V gene complementarity-determining regions. In all three CLLs, the somatic mutations were all identical in multiple Ig VHDJH transcripts at any given time point, and were all conserved at multiple time points throughout a 2-yr period. The lack of concentration of R mutations in the complementarity-determining regions and the lack of intraclonal heterogeneity suggest that Ag may no longer be able to play a significant role in the clonal expansion of these cells. This conclusion would be strengthened further by the germline configuration of the bcl-1 and bcl-2 proto-oncogenes that are translocated in neoplastic B cells that display significant traces of intraclonal diversification and Ag-dependent selection, such as B-prolymphocytic leukemia and low grade follicular non-Hodgkin lymphoma.

Classification of primary gastric lymphomas according to histologic features

Histologic features of low-grade gastric lymphomas of mucosa-associated lymphoid tissue (MALT) have been extensively described, and transformation to a large cell (high-grade) lymphoma can occur. We characterize high-grade gastric lymphoma histologically in an attempt to distinguish between MALT-type and non-MALT-type lesions. We studied a series of 60 gastric lymphomas and characterized them clinically, histopathologically, and immunophenotypically. Low-grade gastric lymphomas were classified according to established criteria. High-grade lymphomas were classified in three groups based on the presence or absence of a low-grade component and lymphoepithelial lesions (LELs): 1) high-grade MALT lymphomas appearing in low-grade MALT lymphomas (LG/HG MALT lymphoma); 2) large cell lymphoma with LELs composed of large cells (high-grade LELs) but without a low-grade component (HG MALT lymphoma); and 3) diffuse large cell lymphoma without a low-grade MALT lymphoma component or LELs (DLCL). Twenty-two lymphomas were classified as low-grade MALT lymphomas, 16 as LG/HG MALT lymphomas, 10 as HG MALT lymphomas, and 12 as DLCL. B-cell immunophenotype was confirmed in all 55 cases in which immunophenotyping was performed. Low-grade LELs were seen in all low-grade MALT lymphomas, and CD20(L26) expression confirmed B-cell phenotype in the LELs in 20 of 20 cases. Clinical follow-up was available for 56 patients (range, 1-264 months; mean, 57 months). Actuarial analysis of disease-specific survival and relapse-free survival showed that clinical stage was highly statistically significant (P < 0.0001), whereas histologic type and grade approached statistical significance. Multivariate analysis showed that clinical stage was the only significant factor in relapse-free and disease-specific survival.

Malignant lymphoma of the bladder: evidence from 36 cases that low-grade lymphoma of the MALT-type is the most common primary bladder lymphoma

Patients with malignant lymphoma of the bladder were studied, and three clinical groups were defined: those with primary lymphoma localized in the bladder, lymphoma presenting in the bladder as the first sign of disseminated disease (nonlocalized lymphoma), and recurrent bladder involvement by lymphoma in patients with a history of malignant lymphoma (secondary lymphoma). The differences in these groups regarding lymphoma type, clinical presentation, and clinical outcome were studied. Mayo Clinic Tissue Registry records from 1940 to 1996 were searched to identify patients with lymphomas involving the bladder. The lymphomas were classified based on review of the histology and immunophenotype performed by immunoperoxidase methods. Clinical records were reviewed. Presenting symptoms included urinary frequency, dysuria, hematuria, and lower abdominal and back pain. Primary lymphoma was present in six patients. All were B-cell lineage low-grade lymphomas of the mucosa-associated lymphoid tissue (MALT) type. No patient had recurrent lymphoma or died of lymphoma. Nonlocalized bladder lymphoma occurred in 17 patients; one with low-grade lymphoma of the MALT type, four with follicle center lymphomas, and 12 with large cell lymphomas. Excluding two patients who died postoperatively, median survival was 9 years. Six patients died of lymphoma in the follow-up period. Secondary bladder lymphoma occurred in 13 patients: two with low-grade lymphoma of the MALT type, one with follicle center lymphoma, one with mantle cell lymphoma, and nine with diffuse large cell lymphomas. Median survival in this group was 0.6 years. Low-grade lymphoma of the MALT type was the most frequent type of primary bladder lymphoma and was associated with an excellent prognosis. The bladder can be the presenting site of lymphomatous involvement in patients with more widespread disease. Survival in this group is quite favorable and is presumably dependent on lymphoma histologic type, stage of disease, and other prognostic factors. Bladder involvement by recurrent lymphoma is a sign of widely disseminated disease and is associated with a very poor prognosis.

A Southwest Oncology Group perspective on the Revised European-American Lymphoma classification

In recent years several new morphologic entities and a new classification system, Revised European-American Lymphoma Classification (REAL), have been proposed which affect the nomenclature and classification of lymphoid malignancies. This article reviews some of the features of the more common new entities, places these entities in immunologic context, explores the clinical utility of these entities, and provides a working clinical organization to the names.

Cell proliferation, bcl-2, c-myc, p53 and apoptosis as indicators of different aggressiveness in small lymphocytic lymphoma (SLL)

Cell proliferation activity, by MIB1 mAb, expression of bcl-2, c-myc and p53 gene proteins and apoptotic index (AI) were assessed in 54 cases of SLL and compared to the morphological subtypes of this disorder, defined by Lennert on the basis of amount and distribution of small and larger activated lymphocytes as diffuse, tumor-forming and pseudofollicular subtypes (DS, TFS, PFS). MIB1 scores showed significant differences between DS, PFS and TFS (5.5%, 16.61% and 24.14%, respectively; p < 0.0001). Worth noting, the MIB1 score did not differ significantly when comparing DS with the diffuse areas of PFS, or TFS with the pseudofollicles of PFS. The mean bcl-2 gene protein score was displayed to a high extent in all subtypes, but less extensively by larger activated lymphocytes that, conversely, expressed c-myc. MIB1 score correlated negatively with bcl-2 and positively with c-myc protein scores. These findings suggest that lymphocytes protected from apoptosis by bcl-2 would be exponed to cell activation and growth acceleration provided by c-myc. This condition would account for a different aggressiveness of morphologically activated subtypes, such as TFS and PFS with larger pseudofollicles. The survival analysis, performed in 23 cases, showed a trend of association of cell proliferation and c-myc expression with a more aggressive progression of the disease. Overexpression of p53 and apoptosis were found only in a minority of cases, unrelated to the subtypes. In conclusion, cell growth fraction, bcl-2 and c-myc assessment may be of help in predicting the aggressiveness of different subtypes of SLL. This approach should be most conveniently applied to PFS, which represents a continuum between DS and TFS, in order to distinguish, in this heterogeneous subtype, more indolent from more aggressive disorders.

Testicular and epididymal plasmacytoma: a report of 7 cases, including three that were the initial manifestation of plasma cell myeloma

We report the cases of six men, 40 to 89 years of age, with testicular (6 cases) or epididymal (1 case) plasmacytoma. Patients presented with a mass in five cases. One tumor was found during evaluation of progressive myeloma. In the final case, the testicular lesion was identified when the patient presented with pathologic fractures. Gross inspection revealed discrete or, less often, ill-defined lesions. Microscopic examination disclosed masses of atypical plasma cells, including binucleated and multinucleated cells and, occasionally, anaplastic cells that obliterated the underlying parenchyma or invaded between seminiferous or epididymal tubules. Immunohistochemical stains on paraffin sections in five cases showed tumor cell expression of monotypic cytoplasmic immunoglobulin. The cells were positive for the leukocyte common antigen (CD45) in three of five cases. All four cases tested were negative for B (CD20) and T (CD3) cell specific antigens and for CD30 and placental alkaline phosphatase. Expression of CD43, CD45RO, and epithelial membrane antigen was found in three, two, and one of four cases respectively. All the patients also had plasma cell neoplasia distant from the testis, identified before (3 cases), concurrent with (3 cases) or after (1 case) the testicular or epididymal plasmacytoma. In one patient a plasmacytoma developed in the contralateral testis three years later; he was alive with plasma cell myeloma 51 months after diagnosis. Another had a plasmacytoma in the contralateral epididymis 8 years later; he also had a nasal cavity plasmacytoma and multiple subcutaneous plasmacytomas, and was alive and well after 26 years. One additional patient was alive with myeloma 6 months later, and four final patients died between 2 months and 3 years after orchiectomy. Three of the four consultation cases in this series were submitted with diagnoses of spermatocytic seminoma, anaplastic seminoma and lymphoma. The diagnosis of plasmacytoma should be borne in mind when examining testicular or paratesticular tumors with a diffuse pattern without glandular differentiation, particularly in men 40 years of age or older.

Molecular Characterization of IgA- and/or IgG-Switched Chronic Lymphocytic Leukemia B Cells

The immunoglobulin (Ig) variable region (V) genes expressed by IgM chronic lymphocytic leukemia (CLL) B cells display little or no somatic mutations. However, preliminary findings have shown that Ig V genes of IgA and IgG CLLs may be somatically mutated, suggesting that isotype-switched CLLs may represent a “subtype” of the disease. To investigate the degree and nature of somatic mutations and the role of antigen (Ag) in the clonal selection and expansion of isotype-switched CLLs, and to determine whether specific oncogene or tumor suppressor gene mutations are associated with isotype-switched CLLs, we analyzed the expressed Ig VH gene, bcl-1 and bcl-2 proto-oncogene, and p53 tumor suppressor gene configurations of 3 IgA-, 1 IgG-, and 1 IgA/IgG-expressing CLLs. These isotype-switched CLL B cells expressed surface HLA-DR, CD19, CD23, and CD5, and displayed no alterations of the bcl-1 and bcl-2 oncogenes and the p53 tumor-suppressor gene. The cDNA VH -D-JH gene sequence was joined with that of the Cα gene in the B cells of the three IgA CLLs, and with that of the Cγ gene in the IgG CLL B cells. In the IgA/IgG-coexpressing CLL B cells, identical VH -D-JH cDNA sequences were spliced to either Cα or Cγ genes. In all five CLLs, the pattern of Cμ DNA probe hybridization to the digested genomic DNAs was consistent with deletion of the Cμ exon from the rearranged Ig gene locus, suggesting that these CLL B cells had undergone DNA switch recombination. In one IgA CLL, the expressed VH gene was unmutated. In all other class-switched CLLs, the Ig VH segment gene was mutated, but the point mutations were not associated with intraclonal diversification. In one IgA and in the IgA/IgG-coexpressing CLL, the nature and distribution of the mutations were consistent with Ag selection. These findings suggest that IgA- and/or IgG-expressing CLLs represent, in their VH gene structure, transformants of B cells at different stages of ontogeny. They also suggest that Ag may play a role in the clonal selection of some of these isotype-switched leukemic cells, but bcl-1 and bcl-2 oncogene rearrangements and p53 tumor suppressor gene mutation are not associated with the pathogenesis of isotype-switched CLLs.

Molecular Characterization of IgA- and/or IgG-Switched Chronic Lymphocytic Leukemia B Cells

The immunoglobulin (Ig) variable region (V) genes expressed by IgM chronic lymphocytic leukemia (CLL) B cells display little or no somatic mutations. However, preliminary findings have shown that Ig V genes of IgA and IgG CLLs may be somatically mutated, suggesting that isotype-switched CLLs may represent a “subtype” of the disease. To investigate the degree and nature of somatic mutations and the role of antigen (Ag) in the clonal selection and expansion of isotype-switched CLLs, and to determine whether specific oncogene or tumor suppressor gene mutations are associated with isotype-switched CLLs, we analyzed the expressed Ig VH gene, bcl-1 and bcl-2 proto-oncogene, and p53 tumor suppressor gene configurations of 3 IgA-, 1 IgG-, and 1 IgA/IgG-expressing CLLs. These isotype-switched CLL B cells expressed surface HLA-DR, CD19, CD23, and CD5, and displayed no alterations of the bcl-1 and bcl-2 oncogenes and the p53 tumor-suppressor gene. The cDNA VH -D-JH gene sequence was joined with that of the Cα gene in the B cells of the three IgA CLLs, and with that of the Cγ gene in the IgG CLL B cells. In the IgA/IgG-coexpressing CLL B cells, identical VH -D-JH cDNA sequences were spliced to either Cα or Cγ genes. In all five CLLs, the pattern of Cμ DNA probe hybridization to the digested genomic DNAs was consistent with deletion of the Cμ exon from the rearranged Ig gene locus, suggesting that these CLL B cells had undergone DNA switch recombination. In one IgA CLL, the expressed VH gene was unmutated. In all other class-switched CLLs, the Ig VH segment gene was mutated, but the point mutations were not associated with intraclonal diversification. In one IgA and in the IgA/IgG-coexpressing CLL, the nature and distribution of the mutations were consistent with Ag selection. These findings suggest that IgA- and/or IgG-expressing CLLs represent, in their VH gene structure, transformants of B cells at different stages of ontogeny. They also suggest that Ag may play a role in the clonal selection of some of these isotype-switched leukemic cells, but bcl-1 and bcl-2 oncogene rearrangements and p53 tumor suppressor gene mutation are not associated with the pathogenesis of isotype-switched CLLs.

Blastoid Variants of Mantle Cell Lymphoma: Frequent bcl-1 Rearrangements at the Major Translocation Cluster Region and Tetraploid Chromosome Clones

Sixty-four cases of mantle cell (centrocytic) non-Hodgkin's lymphomas have been analyzed for their cytomorphologic features, proliferation indices, bcl-1 rearrangements, p53 expression patterns, and DNA content by both interphase cytogenetic and DNA flow cytometric analyses. According to cytomorphology, three subtypes were recognized: a common, a lymphoblastoid, and a pleomorphic variant of mantle cell lymphoma (MCL). Blastoid MCL subtypes were characterized by distinctly elevated mitotic counts (57 and 51/10 HPF v 21/10 high-power fields in common MCL), proliferation indices (58% and 53% v 27% in common types, respectively; P < .001), frequent bcl-1 rearrangements at the major translocation cluster locus (59% v 40%), and overexpression of p53 (21% v 6%). However, the most interesting finding was a striking tendency of blastoid MCL subtypes to harbor chromosome numbers in the tetraploid range (36% of lymphoblastoid and 80% of pleomorphic types v 8% of common variants, P < .001), a feature clearly separating these neoplasms from other types of B-cell non-Hodgkin's lymphoma and possibly being related to cyclin D1 overexpression. Our data indicate that, although characterized by a uniform immunophenotype and common biologic background, MCL shows a broad spectrum of morphologic features ranging from small cell to blastoid types and that the morphologic spectrum is mirrored by distinct biologic features.

VH gene expression in CD5 positive and CD5 negative B cell chronic lymphoid malignancies

In this review, we report analyses of VH genes in mature B cell malignancies generally or occasionally bearing CD5 antigen such as B CLL, MCL, SLVL and PLL. In the majority of cases, B CLL and MCL use VH genes in germline configuration. However in some cases a higher rate of random mutations is observed. These differences are not related to CD5 expression but are accounted by Ig phenotype, since less mutations are observed in CLL cases expressing membrane mu delta, when compared to forms exclusively expressing membrane mu. PLL and SLVL cases display mutated V genes independently of CD5 expression. Although there is some evidence that CD5+ B cells constitute a separate lineage, the possibility that CD5 constitutes an activation marker cannot be ruled out. Indeed, CD5- B cells can be induced to differentiate into CD5+ B cells and VH gene analyses showed no significative differences between CD5+ and CD5- B cell lymphoproliferative disorders. In this review we have tried to examine B cell chronic malignancies on the basis of phenotype and VH gene usage. Thus we propose a tentative classification where these disorders are allocated according to these characteristics.

The value of immunohistochemistry on paraffin wax embedded tissue sections in the differentiation of small lymphocytic and mantle cell lymphomas

AIMS

To determine whether immunohistochemistry applied to paraffin wax embedded biopsy tissue can be used to distinguish between B-small lymphocytic lymphoma (B-SLL) and mantle cell lymphoma (MCL).

METHODS

Formalin fixed, paraffin wax embedded tissue blocks of 12 cases of B-SLL and 12 cases of MCL were retrieved from the files of the Department of Pathology, Southampton University Hospitals Trust. Following antigen retrieval, where appropriate, sections were stained for CD3, CD5, CD20, CD23, CD43, Cyclin D, PGP9.5, and MIB1 using a streptavidin-biotin complex technique.

RESULTS

CD20 stained the neoplastic cells of B-SLL and MCL, and CD3 labelled the reactive T cells in these tumours. In B-SLL, the T cells were generally dispersed among the tumour cells, whereas in MCL they often formed bands around tumour cell nodules. CD5 could be detected on T cells, following antigen retrieval. The level of expression on B cells of B-SLL and MCL was generally too low to allow detection in paraffin wax embedded tissues. CD23 stained B-SLL but not MCL. However, it could be detected in only five of the 12 cases of B-SLL. CD43 could be detected in most cases of B-SLL and MCL. It is not, therefore, of value in distinguishing between these tumours. It will, however, help in the differentiation of B-SLL and MCL from other low grade B cell lymphomas, such as follicle centre cell and marginal zone lymphomas. Cyclin D was expressed in all of the MCL but in none of the B-SLL. PGP9.5 showed reactivity in most cases of MCL and much weaker reactivity in B-SLL. The proliferation indexes of MCL were generally higher than those of B-SLL, as measured by MIB1 labelling. Both tumours, however, showed a wide range of values and considerable overlap.

CONCLUSION

Staining for Cyclin D is the most reliable immunohistochemical mean of differentiating between B-SLL an MCL. High levels of PGP9.5, expressed in MCL, may be related to the degradation of Cyclin D by the ubiquitin pathway.

Primary low-grade B-cell lymphoma of the dura: a mucosa associated lymphoid tissue-type lymphoma

The clinicopathologic findings in five patients with primary low-grade B-cell lymphoma of the intracranial dura are described. All patients were women, 40-62 years of age, who presented with focal neurologic symptoms. Radiologic studies showed a well-localized dural mass in each case, raising a preoperative diagnosis of meningioma. Cytologically these were composed of a diffuse infiltrate of small lymphocytes with plasmacytoid differentiation, with a variable admixture of centrocytelike cells. Lambda light chain restriction was found in three cases, and kappa light chain in one. VJ polymerase chain reaction for immunoglobulin heavy-chain rearrangement was positive in three of four cases, including one case in which immunostaining results were equivocal. Staging procedures did not show involvement at any other site. Therapy consisted of radiation (n = 3), chemotherapy (n = 1), or both (n = 1), with excellent response. There was no evidence of recurrence or subsequent dissemination at follow-up of up to 63 months. Low-grade B-cell lymphomas arising in the intracranial dura are rare but appear to be similar to other low-grade B-cell lymphomas arising in extranodal sites in terms of clinical presentation as stage 1E disease, indolent behavior, and favorable response to treatment, suggesting that they may be part of the mucosa associated lymphoid tissue (MALT) lymphoma spectrum. They appear to arise at dural sites where meningothelial cells are concentrated.

Clinicopathologic study of PRAD1/cyclin D1 overexpressing lymphoma with special reference to mantle cell lymphoma. A distinct molecular pathologic entity

Mantle cell lymphomas (MCLs) are frequently associated with the overexpression of PRAD1/cyclin D1, activated by 11q13 translocation and its molecular counterpart BCL-1 gene rearrangement. We recently described the correlation of positive nuclear staining using monoclonal antibody against a PRAD1/cyclin D1 product with mRNA overexpression in MCLs. In the present study, we immunohistochemically investigated the PRAD1/cyclin D1 protein in a large series of 334 lymphoproliferative disorders, including 39 cases of MCLs on paraffin sections. Based on the cyclin D1 positivity, CD5 expression, and the morphologic features of the tumor tissue, four groups of MCL-related lesions were identified among the B-cell lymphomas examined: 36 cases with cyclin D1 overexpression, 35 (95%) of which exhibited CD5-positivity and MCL-morphology (Group 1); four cases of lymphomas with MCL morphology and CD5 expression but lacking cyclin D1 overexpression (Group II); four cases of lymphomas without cyclin D1 overexpression and surface CD5 but that fall within the morphologic boundaries of MCLs (Group III); and 11 cases of CD5-positive diffuse large cell lymphomas without cyclin D1 overexpression (Group IV). The Group I cases demonstrated quite homogeneous clinicopathologic features identical to those of MCLs. This group showed a poor prognosis (11% had 5-year survival), which is highly contrasted with that of Group II (100%). Although the four groups of MCL-related lesions sometimes overlapped in their histologic or phenotypic spectrums, each appeared to show distinct clinicopathologic and prognostic profiles. Our study provides a basis for further clarification of the nature of the neoplasms of Groups II, III, and IV. Moreover, this comprehensive study may indicate that the overexpression of PRAD1/cyclin D1 is biologically essential to defining MCLs.

Mantle cell lymphoma. A morphological, immunohistochemical and molecular genetic study

In order to identify helpful markers in the classification of mantle cell lymphoma, a morphological, immunohistochemical and molecular genetic analysis of 41 cases of NHL, originally referred to us as CC, ILL or IDL, was performed. We revised these lymphomas using the strict morphological criteria described in the updated Kiel classification and the more recently described criteria for MCL. The term MCL was used to designate the small lymphocytic B-cell NHL, previously referred to as CC or ILL/ IDL. This revision yielded 20 MCL, 8 CLL, 3 Cb/Cc, 1 CB, 6 IC and 3 MALT lymphomas. The presence of scattered histiocytes was seen in 90% of MCL and 5% of the other cases. No other morphological parameter, besides the used criteria, differentiated between MCL and similar small lymphocytic B cell lymphomas. Helpful immunohistochemical markers to distinguish MCL from similar small lymphocytic lymphomas were CD5+, CD10-, CD23- and Alkaline Phosphatase+. Large fields of dendritic reticulum cells, often in a loose and disrupted arrangement were seen in 82% of MCL and in 19% of the other lymphomas. Analysis with Southern blotting showed a rearrangement in the BCL-1 locus in 12/20 cases of MCL but not in the other 21 lymphomas. Although very specific for MCL, Southern blotting to detect BCL-1 rearrangements is, due to the large number of probes necessary, not of great help in daily practice for routine diagnostic purposes. We conclude that using strict morphological criteria, the diagnosis MCL can be made reliably and that immunophenotyping is helpful in supporting the diagnosis.

Marginal zone lymphoma (low-grade B-cell lymphoma of mucosa-associated lymphoid tissue type) of skin and subcutaneous tissue: a study of 15 patients

Extranodal low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type occurs in the gastrointestinal tract, salivary gland, thyroid, orbit, lung, and breast. We report 15 patients with MALT-type lymphomas involving skin and subcutaneous tissue. All patients had tumors with histologic features of low-grade B-cell lymphoma of MALT type, including marginal zone cells (15 of 15 cases), plasmacytic differentiation (10 of 15 cases), Dutcher bodies (three of 15 cases), and reactive germinal centers (10 of 15 cases). All expressed pan B-cell antigens and monotypic immunoglobulin. Seven patients (five women, two men) aged 29 to 86 years (median, 53 years) had primary MALT-type lymphoma of skin (6) or subcutaneous tissue (1). One patient had persistent disease, and four patients had relapses involving skin, subcutaneous tissue, breast, orbit, and lymph node. At last follow-up (11-121 months; median, 36 months), one patient was alive with disease, and six patients had no evidence of disease. Three patients (two women, one man) aged 36 to 67 years (median, 57 years) had concurrent MALT-type lymphoma involving both subcutaneous tissue and extracutaneous sites at primary diagnosis, including lung, breast, orbit, lymph node, and bone marrow. One patient responded to treatment but relapsed with lymphoma of the skin and breast. The other two patients had persistent disease despite treatment. One patient died of disease at 25 months, and, at last follow-up (7 and 46 months), two patients were alive with disease. Five patients (four women and one man) aged 29 to 72 years (median, 63 years) had secondary skin or subcutaneous involvement by MALT-type lymphoma with primary tumors of ocular adnexa (3) or parotid gland (2). All five patients had relapses, which involved skin or subcutaneous tissue, parotid gland, lacrimal gland, breast, and lymph node. At last follow-up (61-137 months), two patients were alive with disease and three were alive with no evidence of disease. Low-grade B-cell lymphomas of MALT type may arise in or secondarily involve the skin and subcutaneous tissue and have a tendency to affect middle-aged to older women. These tumors are characterized by multiple extranodal relapses and are associated with long patient survival. Patients with primary MALT-type lymphoma of skin or subcutaneous tissue without extracutaneous involvement at diagnosis were more likely to experience prolonged disease-free survival than patients with extracutaneous spread at presentation (p < 0.03).

CD5-expressing B-cell lymphomas/leukemias: relatively high frequency of CD5+ B-cell lymphomas with an overall poor prognosis in Nagasaki Japan

To characterize CD5+ B-cell neoplasms in Japan, where chronic lymphocytic leukemia (CLL) is rare and of different subtypes in comparison with Western countries, we collected 58 cases of CD5+ B-cell lymphomas/leukemias and analyzed their clinicopathologic features. According to the French-American-British (FAB) and standard histologic classification, the cases corresponded to small lymphocytic lymphoma (SLL, group I; n = 22, consisting of CLL, n = 10, CLL/PL, n = 3, and CLLmixed, n = 7); intermediate differentiated lymphoma/mantle cell lymphoma (IDL/MCL, group II, n = 18); and others with CD5-positive lymphomas (group III, n = 18). The CD5+ B-cell lymphomas showed morphologic and prognostic variability among the three groups. The clinical and immunophenotypic features were remarkably consistent in leukemic disease being seen in 73% of all cases, splenomegaly in 63%, and intense CD19, CD20, surface membrane immunogobulin M (SmIgM) or SmIgM and SmIgD, light-chain expression, and no CD10 expression. The median survival time of groups I, II, and III was 7.8, 3.3, and 0.8 years, respectively. These findings suggest that CD5 antigens may serve as valid markers for the prognosis and clinical features of B-cell lymphomas and that CD5+ B-cell lymphomas with an overall poor prognosis occurs at a relatively high frequency in Japan. This also suggests that a combination of immunophenotypic and morphologic features is of value for characterizing CD5+ B-cell neoplasms.

The morphologic spectrum of non-Hodgkin's lymphomas with BCL1/cyclin D1 gene rearrangements

BCL1/PRAD1 gene rearrangements involving the cyclin D1 gene are a feature of about 70% of centrocytic/mantle-cell lymphomas (CC/MCL) but are identified in only a small proportion of other B-cell non-Hodgkin's lymphomas. Of 37 lymphomas found to have BCL1/cyclin D1 (PRAD1, CCND1) gene rearrangements, 30 fit the morphologic and immunophenotypic criteria for typical CC/MCL. Seven cases with morphologic features atypical for CC/MCL were identified. CD5+ monoclonal B cells were documented in all these cases. Six cases were subsequently stained for cyclin D1 protein, and all showed nuclear positivity. Five cases had variably sized foci of cells with moderately abundant pale cytoplasm resembling parafollicular/monocytoid B cells, marginal zone cells, hairy cells, or even proliferation centers. Transformed-appearing cells were also present in some lymphomas. In one case, striking follicular colonization created a markedly nodular growth pattern mimicking a follicular lymphoma. A sixth case had a marked predominance of small, round lymphocytes at some sites, mimicking a small lymphocytic lymphoma. Five of these six cases also had areas more typical of CC/MCL. The seventh case was a CD5-positive splenic marginal zone-like lymphoma (SMZL) with plasmacytic differentiation and circulating villous lymphocytes consistent with a splenic lymphoma with villous lymphocytes (SLVL). These cases illustrate the morphologic spectrum of small B-cell lymphoid neoplasms that have BCL1/cyclin D1 gene rearrangements and overexpression of cyclin D1. Despite the BCL1 translocation and cyclin D1 overexpression, the splenic lymphoma with plasmacytic differentiation was definitely not a CC/MCL and fit the clinicopathologic entity of SMZL/SLVL. The other six cases are best considered CC/MCL variants based on a combined morphologic, immunophenotypic, and genotypic evaluation. Genotypic or immunophenotypic studies to identify cyclin D1 rearrangements and overexpression, although not pathognomonic, are useful in recognizing these variant CC/MCL cases, which can mimic almost any of the other well-described but more indolent low-grade B-cell lymphomas and leukemias. Some of the variant CC/MCL cases had features in common with the CD5+ cyclin D1+ SMZL/SLVL, suggesting a possible relationship between these two otherwise distinct entities.

Translocation t(8;16)(p11;p13) in acute non-lymphocytic leukemia: report on two new cases and review of the literature

Two new cases of t(8;16)(p11;p13) in acute nonlymphocytic leukemia (ANLL) are described. These two patients in addition to the 34 previously described, showed a striking association with myelomonocytic (M4) or monocytic (M5) leukemia, extramedullary infiltration, erythrophagocytosis and disseminated intravascular coagulation. One of our patients showed a TCRbeta gene rearrangement. Alltogether 36 cases of t(8;16) ANLL have been documented until today. We here review their clinical and cytogenetic features.

Immunohistochemistry in diagnostic dermatopathology

Immunopathology continues to be important in diagnostic dermatopathology. Immunopathology is an invaluable tool for assessing the tissue of origin or direction of differentiation of cells. In some cases this can result in a more precise diagnosis. This article reviews the role of immunopathology in determining the biologic behavior of hematolymphoid infiltrates. It explores the methodology of immunoperoxidase, discusses the most commonly used antibody reagents, and presents a series of diagnostic dilemmas in which immunopathology can be useful. In each case a strategy is established that maximizes the likelihood of making a definitive diagnosis.

New classification of low-grade lymphoma

The problem of morphologic classification of the indolent non-Hodgkin's lymphomas has been addressed by the National Cancer Institute Working Formulation, the International Lymphoma Study Group, and other groups. The criteria for classification have expanded to include biologic and laboratory parameters. Clinical aspects are important, because diagnostic categories that obscure discrete entities, such as mucosa-associated B-cell lymphoma could adversely affect therapy. This and other indolent non-Hodgkin's lymphomas and mantle-cell lymphoma, which has been provisionally included among them, are reviewed. Variations in nomenclature, immunohistochemical and molecular characteristics, and whenever possible, prognosis and clinical outcome are described. The need for further correlation with clinical outcome of these entities is noted.

Low-grade lymphomas: new entities and treatment concepts

Therapy for patients with low-grade lymphomas has never been standardized. Recently, new entities have been described which are included in the REAL classification, and whether these entities should be regarded as separate diseases is not yet clear. Regardless, three new developments in the management of patients with low-grade lymphomas deserve special attention for treatment programs in the future. First, it appears that patients with stage I, II, and III low-grade lymphomas may enjoy very prolonged disease-free intervals after treatment with combination chemotherapy and radiation therapy programs. Although investigators disagree on prognostic factors, new features, such as beta 2-microglobulin appear to predict results better than any other feature, and future studies should address this prognostic factor in assessing their results. Second, for patients with advanced stage disease, administration of interferon as maintenance therapy prolongs the disease-free interval, and use of this drug should be further investigated. Finally, molecular studies using PCR for bcl-2 may be clinically relevant in detecting residual disease in patients with follicular lymphomas, and future studies should focus on the value of eliminating the residual disease from blood and marrow.

UCL3D3 and UCL4D12 reactivity in small B-cell neoplasms with special emphasis on monocytoid B-cell lymphoma

Two recently described monoclonal antibodies, UCL3D3 and UCL4D12, have been reported to have some specificity for mantle zone B lymphocytes and marginal zone/follicular center B lymphocytes, respectively, in the spleen. Forty-nine B-cell neoplasms, including 20 cases of monocytoid B-cell lymphoma (MBCL), were studied by frozen section immunohistochemistry with these antibodies to evaluate their utility. Tonsil, lymph node, and reactive spleen also were studied with the antibodies. Although a wide overlap was observed among the different lymphomas, a majority of cases of MBCL and half of cases of hairy cell leukemia (HCL) reacted with both markers, suggesting both marginal/follicular and mantle cell antigen expression. None of four cases of mantle cell lymphoma reacted with the proposed mantle cell marker UCL3D3, whereas three of these cases immunoreacted with UCL4D12. This marker is known to react with a subpopulation of follicular center cells and possibly with marginal zone lymphocytes. A comparison of nodal and extranodal neoplasms failed to show a significant difference in the pattern of immunoreactivity with these antibodies. Tonsil and lymph node controls showed some mantle zone staining with both antibodies, and there was a slight overlap in mantle and marginal zone staining of the spleen controls. These findings suggest an immunologic similarity between some cases of HCL and MBCL. However, the findings also would suggest that these antibodies, particularly UCL4D12, have less specificity than has been previously assumed, and UCL4D12 may not have practical utility in the evaluation of low grade B-cell lymphomas.