The World Health Organization classification of hematological malignancies report of the Clinical Advisory Committee Meeting, Airlie House, Virginia, November 1997

Progression to large B-cell lymphoma in splenic marginal zone lymphoma: a description of a series of 12 cases

Splenic marginal zone lymphoma (SMZL) is considered to be an indolent extranodal B-cell lymphoma. Despite its low aggressivity, histologic progression has been described in sporadic reports, although the frequency, characteristics, and underlying molecular abnormalities of this phenomenon are largely unknown. We review here the clinical, morphologic, immunohistochemical, and molecular features of a series of 12 SMZL cases that showed progression to large B-cell lymphoma (LBCL). The most frequent location of secondary LBCL was in peripheral lymph node. This occurred between 12 and 85 months after diagnosis of SMZL. However, in two cases LBCL was diagnosed at the initial stage of the disease (one spleen tumoral nodule and one hilar lymph node). The histologic and immunophenotypic features of these cases were similar to those of transformed LBCL at other sites. In four cases the immunoglobulin heavy chain gene polymerase chain study revealed the same rearrangement pattern in both primary and secondary tumors, thereby confirming their identity and excluding the possibility of a second malignancy. As is the case with other low-grade lymphoproliferative disorders, SMZL may undergo high-grade transformation. These 12 cases represent 13% of our series of SMZL with adequate follow-up. The incidence of large cell transformation in SMZL seems to be lower than in follicular lymphoma (25-60%) and mantle cell lymphoma (11-39%), although it is similar to the frequency of transformation in B-chronic lymphocytic lymphoma/small lymphocytic lymphoma (1-10%). The mean proliferative index (MIB1 staining) in initial SMZL specimens of cases with LBCL transformation was 28.6%, higher than that of MIB1 staining in the overall SMZL series (21.8%), although not statistically significantly so. p53 or p16INK4a inactivation in this series was observed in only one case, in contrast with the situation observed in chronic lymphocytic leukemia, follicular lymphoma, and mantle cell lymphoma. It seems that progression in SMZL is mainly independent of p53 or p16INK4a inactivation. The frequency of the 7q deletion in this series was 3 of 7 (42%). 7q loss may play an alternative role in the inactivation of the p53 and p16INK4a pathway, thereby favoring tumoral progression.

Immunophenotypic analysis of peripheral T-cell neoplasms. A multiparameter flow cytometric approach

We retrospectively reviewed multiparameter flow cytometric analyses in 50 peripheral T-cell neoplasms (PTCNs). Results were interpreted within the context of a large cohort of nonneoplastic T-cell populations. All PTCN diagnoses were confirmed with morphologic and/or molecular analysis. Aberrant populations were defined as discrete immunophenotypic clusters exhibiting loss of or increased or diminished expression of T-cell antigens relative to internal immunophenotypically normal T-cell populations. An antigenic pattern was considered abnormal if it exceeded ranges for T-cell subsets in specific anatomic sites or was not normally encountered. Forty-six of 50 and 41 of 50 demonstrated 1 or more and 2 or more aberrations, respectively. The most common abnormally expressed antigen was CD3, followed by CD7, CD5, and CD2. Except for CD7, abnormally dim or bright antigen expression was more common than deletion. Only 3 cases were abnormal solely based on expansion of an otherwise immunophenotypically normal population; the remainder had patterns of antigen expression not seen in nonneoplastic populations. These data indicate that most PTCNs are aberrant by multiparameter flow analysis. However, results must be interpreted within the context of thorough knowledge of the immunophenotypic spectrum of nonneoplastic T cells.

Molecular features of B-cell lymphoma

Malignant transformation of B cells can occur at various steps of lymphocyte development, starting from early B-cell progenitors up to mature B cells, which reflects the heterogeneity of B-cell malignancies with regard to their biologic and clinical behavior. The genetic characterization of B-cell neoplasms during the past two decades has elucidated the mechanisms underlying B-cell lymphomagenesis and led to a more precise definition of lymphoma subgroups. This progress is reflected in the upcoming World Health Organization classification for hematologic neoplasms, which stresses the diagnostic importance of recurrent genetic alterations in leukemias and lymphomas. In the recent past, several genes deregulated by such recurrent chromosomal aberrations have been identified. In addition, the recent introduction of microarray technology has now allowed a more global assessment of gene dysregulation in B-cell oncogenesis and provided a new means for more exactly defining the molecular hallmarks of distinct lymphoma subtypes. This review will focus on recently described molecular features of B-cell lymphomas discovered by the application of new molecular cytogenetic techniques, advanced breakpoint cloning strategies, and microarray approaches.

Primary extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue type in the CNS

Extranodal marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue (MALT) type has been reported in various internal organs. Here a case is reported of MALT lymphoma developing in the cerebellopontine (CP) angle in a patient with Sjogren syndrome, and the concept of MALT lymphoma of the CNS is introduced. Pathologically, the tumor showed inflammatory features of reactive lymphocytic infiltration with follicle formation, but there were slightly atypical lymphocytes and plasmacytes with B-cell markers. These cells invaded reactive follicles, showing follicular colonization, and showed aberrant expression indicating their neoplastic nature. A review of the literature revealed eight cases of MALT lymphoma originating from the dura mater and one from the CP angle. The average age of patients was 50 years (range 28-66 years), and all patients were female. The tumors were slow to develop and the patients were cured after surgical removal and/or additional therapies. It is proposed that MALT lymphoma should be considered as a differential diagnosis of inflammatory pseudotumor of the CNS.

Higher levels of surface CD20 expression on circulating lymphocytes compared with bone marrow and lymph nodes in B-cell chronic lymphocytic leukemia

Differential expression of CD20 surface antigen in B-cell neoplasms at different sites is largely unknown. The number of CD20 antibodies bound per cell (CD20 ABC) in bone marrow (BM), peripheral blood (PB), and lymph node aspirate (LNA) samples from patients with B-cell chronic lymphocytic leukemia (B-CLL) or other B-cell disease was studied using quantitative flow cytometry. CD20 ABC differed significantly with the specimen type in B-CLL, being highest in PB (mean, 9,051) and lower in BM (mean, 4,067) and LNA (mean, 3,951). No difference in CD20 ABC between BM and PB samples was found in splenic lymphoma, mantle cell lymphoma, or follicular lymphoma. Also, we found a significant difference of CD20 ABC by type of disease: lowest in B-CLL; higher in splenic, follicular, and mantle cell lymphoma; and highest in hairy cell leukemia. The lower CD20 surface antigen levels in BM and LNA than in PB in B-CLL may have clinical relevance with regard to the efficacy of rituximab therapy.

Detection of translocations involving the HOX11/TCL3-locus in 10q24 by interphase fluorescence in situ hybridization

The t(10;14)(q24;q11) and its variant t(7;10)(q35;q24), which are recurrent in acute T-cell leukemia, lead to activation of the HOX11/TCL3-gene in chromosomal region 10q24 by juxtaposing this gene to one of the T-cell receptor loci. In the present study, we established a diagnostic assay for detecting these translocations by interphase fluorescence in situ hybridization (FISH). BAC clones flanking the HOX11/TCL3-locus were obtained from a fingerprinted BAC-contig of chromosomal region 10q24. BAC clones located proximal and distal of the HOX11/TCL3-locus were differently labeled and applied to interphase-FISH in seven normal controls and eight T-cell neoplasms with t(10;14)(q24;q11) or t(7;10)(q35;q24). In over 1600 nuclei of controls, a considerable split defined as separation of each one signal for the proximal and distal probe by more than three times the signal diameter was observed in only one cell. In contrast, all T-cell neoplasms with t(10;14) or t(7;10) contained at least 47% of nuclei with a signal split indicating a breakpoint in the HOX11/TCL3-locus. Thus, the established double-color FISH approach provides a new reliable and routinely applicable tool for diagnosing breakpoints in the HOX11/TCL3-locus.

Bone marrow mast cell morphologic features and hematopoietic dyspoiesis in systemic mast cell disease

Systemic mast cell disease (SMCD) cannot be distinguished from reactive mastocytosis (RM) by quantitation of mast cells in aspirate smears, and few studies have analyzed systematically the morphologic features of mast cells in SMCD vs RM. In addition, although SMCD is associated with myeloproliferative disorders/myelodysplastic syndromes (MPD/MDS), it is not known whether subtle signs of dysplasia or MPD can be found in SMCD, suggesting most cases are part of a dysplastic or myeloproliferative process. We compared 18 bone marrow specimens with SMCD with 10 bone marrow specimens from patients with RM. Mast cells in SMCD were more likely to show cytoplasmic hypogranularity, uneven granule distribution, and fusiform morphologic features. Eight cases of SMCD (44%) demonstrated MPD/MDS, and 9 cases (50%) showed subtle evidence of dyspoiesis, with megaloblastic change, nuclear budding of erythroid precursors, and/or atypical megakaryocytes. Mast cells in SMCD appear morphologically different from those in reactive proliferations. Dyspoietic features were present in most cases of SMCD, suggesting that SMCD is part of a spectrum of chronic myeloproliferative/myelodysplastic disorders.

Lymphoma immunophenotyping: a new era in paraffin-section immunohistochemistry

Recent advances in immunohistochemistry have made it possible to investigate lymphomas for the expression of a wide range of antigens in fixed tissues. Epitope retrieval, sensitive detection methods, and the availability of new monoclonal antibodies have all contributed to one's ability to perform detailed immunophenotyping that previously could only be done in cryostat sections or by flow cytometry. Current lymphoma classifications make use of characteristic immunophenotypic profiles that aid in the reproducible diagnosis and subcassification of these neoplasms. The following is a review of the current state of immunophenotyping for lymphoid neoplasms in fixed tissues.

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.

1,3-Butadiene, isoprene and chloroprene: reviews by the IARC monographs programme, outstanding issues, and research priorities in epidemiology

1,3-Butadiene, isoprene and chloroprene have all been evaluated more than once by the IARC Monographs Programme on the Evaluation of Carcinogenic Risks to Humans, most recently in February 1998 (Volume 71). Summaries are available on-line at http://monographs.iarc.fr. 1,3-Butadiene is currently classified in Group 2A (probably carcinogenic to humans), on the basis of limited evidence for increased occupational cancer risk in humans plus sufficient evidence of carcinogenicity at multiple organ sites in rats and especially in mice exposed by inhalation. Four epidemiologic studies are available on cancer risk among workers exposed to 1,3-butadiene, one large study among styrene-butadiene rubber (SBR) workers, and one large and two small studies among 1,3-butadiene production workers. The results of the study of SBR workers suggest an association between butadiene exposure and leukaemia risk, which is consistent with the results of the large study of production workers. This latter study also suggested an increased risk of lymphoreticulosarcoma (ICD-8, 200). The major factors hampering the assessment of the available results are (i) possible misclassification of lymphoid and haematopoietic neoplasms, (ii) limitations in the assessment of past exposure (with the exception of the study of SBR workers) and (iii) a potential confounding effect of agents other than butadiene. Future research priorities include (i) the incorporation of newly developed biomarkers of exposure, (ii) the possible application of intermediate biomarkers, (iii) the replication of the study among SBR workers, possibly in Europe, and (iv) reanalysis of existing data in light of revisions of the classifications of leukaemias and lymphomas in the International Classification of Diseases for Oncology, Third Edition (2000). Isoprene is classified in Group 2B (possibly carcinogenic to humans), on the basis of sufficient evidence for carcinogenicity at multiple organ sites in both mice and rats, especially male mice, exposed by inhalation. No epidemiologic studies are available on cancer risk from occupational exposure to isoprene. Such studies could be conducted within the framework of existing or future studies of SBR workers, assuming that isoprene exposure can be disentangled from butadiene and styrene exposure. Chloroprene is classified in Group 2B on the basis of sufficient evidence for carcinogenicity at multiple organ sites in both mice and rats exposed by inhalation. Studies of chloroprene exposed workers now include chemical workers from the United States, China and Armenia as well as shoe workers from Russia. The results of the studies from China, Armenia and Russia suggest an excess risk of liver cancer. The risk of other neoplasms was not consistently increased. Limitations of available studies include possible bias from cohort enumeration, follow-up, and choice of reference population. In most studies the exposure assessment was poor, the possible confounding effect of co-exposures was not addressed and the statistical power was low. The pathology of the cases of liver cancer should be reviewed. Future research priorities include a replication of available studies in well-defined populations and the development of biomarkers of exposure.

Fine-Needle Aspiration Biopsy in the Diagnosis and Classification of Primary and Recurrent Lymphoma: A Retrospective Analysis of the Utility of Cytomorphology and Flow Cytometry

We retrospectively reviewed our experience with the fine-needle aspiration biopsy (FNAB) diagnosis of primary and recurrent lymphoma to assess the ability of cytomorphology with and without ancillary flow cytometry (FCM) analysis to diagnose and subclassify these tumors according to the Revised European-American Lymphoma/World Health Organization classifications. We reviewed 139 consecutive FNABS of 84 primary and 55 recurrent lymphomas. FCM was successful in 105 (75%) cases. The overall results, including cases without FCM, included 93/139 (67%) true positive, 7 (5%) false negative, and 39 indeterminate (27 [19%] suspicious and 12 [9%] atypical) diagnoses of lymphoma. In cases with FCM, there were 80/105 (77%) true positive, no false negative, and 25 indeterminate diagnoses (15 [14%] suspicious and 10 [9%] atypical). The overall results of the 84 primary lymphomas were 55 (67%) true positive, 5 (5%) false negative, and 24 indeterminate (14[16%] suspicious and 10 [12%] atypical) diagnoses for lymphoma. Of the 68 primary lymphomas analyzed with FCM, 50 [74%] were true positives, and 28 were indeterminate (11 [16%] suspicious and 7 [10%] atypical). There were no false negatives. Diagnostic accuracy varied among lymphoma subtypes. Subclassification of the positive cases were initially conclusive in only 55/93 cases (59%). However, a retrospective review of the morphologic together with FCM data in 15 of the 23 unclassified cases improved the overall subclassification of positive cases to 77%. Subclassification was best in small lymphocytic lymphoma/chronic lymphocytic leukemia, lymphoplasmacytic lymphoma, Burkitt's lymphoma, mantle cell lymphoma, and plasmacytoma (all 100%). Subclassification was poor in marginal-zone lymphoma (33%), and initially as well in diffuse large B-cell lymphoma (62%), but it improved on review (95%), as did subclassification of follicular lymphoma (77 to 100% on review). Hodgkin's disease was recognized as malignant in only 44% of the cases (7/16) and was classified as such based on morphology alone. This review of our early efforts to diagnose and subclassify lymphoma with FNAB and FCM indicates that although a diagnosis and proper subclassification of lymphoma can be made with certainty in the majority of cases, recurrent or primary, it requires close coordination of cytomorphology and immunophenotyping data, which often comes with close cooperation of cytopathologists and hematopathologists. A mere cytological diagnosis of positive for lymphoma is no longer acceptable if FNAB is to become an independent diagnostic tool for lymphoma.

Is myelodysplastic related acute myelogenous leukemia a distinct entity from de novo acute myelogenous leukemia? Potential for targeted therapies

Acute myelogenous leukemia (AML) can be separated by whether the presentation was proceeded by a myelodysplastic (MDS related AML) or developed de novo (dAML). Clinically, MDS related AML (mAML) has been considered to have a worse prognosis that dAML. The objective of this literature review was to identify unique biologic features of mAML. Compared to dAML, mAML is characterized by an altered immunophenotype (increased frequency of CD34, CD11b and CD25), lack of leukemic progenitor cell suppression due to TGFbeta1, increased bcl-2 expression, presence of inducible nitric oxide synthase, lower levels or mrp transcripts and increased expression of p53. Possible interpretations of these differences between mAML and dAML are presented. Implications for mAML directed therapy are discussed.

Early-stage Hodgkin's disease

Treatment of Hodgkin's disease (HD) is strictly dependent on stage. Historically, early-stage HD included the limited stages I, II, and IIIA (according to the Cotswolds modification of the Ann Arbor classsification), whereas advanced HD included stage III with B symptoms and stage IV. It was then observed that early-stage HD with certain clinical risk factors had a significantly worse outcome. As a consequence, several studies defined these patients as suffering from early-stage unfavorable (or intermediate-stage) HD, demanding a more aggressive treatment. The treatment of early-stage HD is changing strikingly. Until recently, extended-field (EF) irradiation has been considered the standard treatment. However, because of the recognition of its high relapse rate and fatal long-term effects, EF radiotherapy is now being abandoned by most study groups. Instead, for favorable early-stage HD, mild chemotherapy for control of occult disease is combined with involved-field (IF) irradiation. In early-stage unfavorable (intermediate) HD, four cycles of chemotherapy plus IF irradiation is accepted as standard treatment.

The diagnostic significance of Myf-3 hypermethylation in malignant lymphoproliferative disorders

Deregulated methylation of cytosine in DNA is a frequent finding in malignancy that is reflected by general genomic hypomethylation and regional hypermethylation that includes the myogenic gene Myf-3. In this study of 198 DNA samples from 186 patients with a wide range of lymphoproliferative disorders (LPD), the methylation status of Myf-3 was assessed to evaluate its significance in the diagnosis of malignant LPD. DNA was digested with the restriction endonucleases HpaII and MspI, and using the Southern blot (SB) technique, the size and density of fragments that hybridized with a Myf-3 probe were used to assign the methylation status. None of the samples from 45 patients from a wide age range with benign LPDs had evidence of altered Myf-3 methylation and there was no age-related methylation change. By contrast, 115/123 (93%) of samples from patients with non-Hodgkin lymphoma (NHL) or lymphoid leukemia had increased Myf-3 methylation. There was no methylation alteration in 22/24 (92%) of samples from patients with Hodgkin lymphoma (HL), nor in five of six samples from LPDs that had atypical histopathologic features which were not diagnostic of lymphoma, while the remaining sample of atypical LPD had hypermethylated Myf-3 fragments. There was an association between increasing Myf-3 methylation and higher histopathologic grade of malignancy within specific lymphoma categories. It is concluded that the detection of increased Myf-3 methylation is a sensitive and specific test of malignancy which may complement other molecular methods that are currently used for the assessment of clonality. It may be of particular diagnostic use in natural killer (NK) and null cell malignancies for which other indicators of clonality are lacking. Furthermore, methylation status may prove to be of potential prognostic value.

Primary endometrial T-cell lymphoma. A case report

Primary lymphomas of the female genital tract are rare. Most involve the cervix rather than the uterine corpus. All of those previously reported have been B-cell lymphomas, with the exception of 1 case report of an endometrial T-cell lymphoma in a Japanese woman. We report the case of a white woman from the United States with a diffuse large cell lymphoma of the endometrium, characterized as a peripheral T-cell type on the basis of immunophenotypic and molecular probe studies. Staging evaluation revealed tumor limited to the endometrium (stage IE). The patient underwent a total abdominal hysterectomy, bilateral salpingo-oophorectomy, and lymph node dissection and received 6 cycles of combination chemotherapy, after which she remained free of disease at last follow-up of 36 months. Unusual features of this lymphoma case are discussed, with emphasis on differential diagnosis and speculation on histogenesis. This case illustrates that, while most peripheral T-cell lymphomas are widely disseminated at presentation, those limited to a single extranodal site may have a favorable outcome akin to that associated with high-grade extranodal B-cell lymphomas of early stage.

Chromosomal analyses of 52 cases of follicular lymphoma with t(14;18), including blastic/blastoid variant

We have identified 52 patients of follicular lymphoma (FL) with t(14;18)(q32;q21). Histologically, the lymphomas were placed into six groups according to their cellular composition and growth pattern. Chromosome analysis revealed that all cases but one had additional secondary chromosomal abnormalities. The most frequent numerical aberrations were gains of chromosomes 7 (38%), X (36%), 5 (15%), 12 (15%), 18/der(18)t(14;18) (25%), and 21 (15%). Structural abnormalities of chromosome 1 were seen in 19 tumors (36%) affecting both arms with breakpoints clustered at 1p36. Other structural abnormalities included partial deletions of 6q, 10q, and 13q. Breakpoint at 8q24 was seen in four cases. The chromosome aberrations were correlated with the morphological subtypes of follicular lymphoma. Gain of chromosome 7 appeared to be associated with follicular large cell lymphoma. The incidence of trisomy 5 and 12, and 13q- was higher in follicular lymphoma with aggressive histological features than in low-grade lymphoma. In addition, complexity of the karyotype and high degree of polyploidy increased with the grade. The most valuable cytogenetic markers in the t(14;18) lymphomas are those involving 8q24 which was found exclusively in the blastic/blastoid variant FL. Therefore, chromosome analysis in relation to histologic pattern of follicular lymphoma can provide additional information in predicting tumor evolution and transformation to a higher-grade malignancy.

Hepatosplenic alphabeta T-cell lymphomas: a report of 14 cases and comparison with hepatosplenic gammadelta T-cell lymphomas

Hepatosplenic gammadelta T-cell lymphoma is a distinct entity, characterized by occurrence in young adult males with hepatosplenomegaly, B-symptoms, peripheral blood cytopenias, and no lymphadenopathy; lymphomatous infiltrates in the splenic red pulp, hepatic sinusoids, and bone marrow sinuses; T-cell receptor (TCR) gammadelta chains and a cytotoxic T-cell phenotype; isochromosome 7q; and an aggressive clinical course. In comparison, this study describes the clinicopathologic features of 14 hepatosplenic T-cell lymphomas expressing TCR alphabeta chains. They occurred in 11 women and 3 men with a median age of 36 years. Clinical presentation was similar to that described previously for hepatosplenic gammadelta T-cell lymphomas, except for the female preponderance and age distribution (5 patients younger than 13 years of age and 5 patients older than 50 years of age). Disease distribution was primarily in the splenic red pulp and hepatic sinusoids, although liver infiltrates were largely periportal in four cases. Bone marrow involvement, observed in eight patients, was usually interstitial and/or within the sinuses. Lymph nodes were involved in five patients, although lymphadenopathy was demonstrable in only two. Ten cases were composed of intermediate-size tumor cells with round/oval nuclei, slightly dispersed chromatin, inconspicuous nucleoli, and scant to moderate amounts of cytoplasm. Four lymphomas contained primarily large cells with irregular nuclei, dispersed chromatin, discernible nucleoli, and moderate to abundant cytoplasm. Tumor cells in all 14 lymphomas were cytotoxic alphabeta T-cells; 13 co-expressed natural killer cell-associated antigens and showed T-cell clonality. Three lymphomas were associated with Epstein-Barr virus. Two of four cases had an isochromosome 7q. Eleven patients are dead, eight within a year of diagnosis, and two patients have maintained complete remissions after combination chemotherapy. These data show that hepatosplenic T-cell lymphomas include an alphabeta-subtype. This group, along with the previously recognized gammadelta group, should be recognized as phenotypically heterogeneous subtypes of the same disease entity.

Immunophenotypic and genotypic markers of follicular center cell neoplasia in diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCL) are a biologically and clinically heterogeneous entity. Although some DLBCL represent transformation of follicular lymphomas (FL), the proportion that is of follicular center cell (FCC) origin remains uncertain. Immunophenotypic and genotypic markers used to suggest a FCC origin for a lymphoma (bcl-6 and CD10 expression, lack of CD138 expression, bcl-2 rearrangements [R]) or to subdivide DLBCL (bcl-2 expression, bcl-6 R) were therefore investigated in 22 FL and 44 DLBCL using paraffin section immunostains and Southern blot/polymerase chain reaction analysis. All FL tested were bcl-6+ (19) and CD138- (22) with 16/19 also bcl-2 and CD10+ (classic phenotype), one bcl2+, CD10- (grade III) and two bcl2-, CD10+ (grade II or III). Bcl-2R was identified in 4/5 FL-GrI, 3/6 FL-GrII, and 1/3 FL-GrIII. Bcl-6R was found in 0/5, 2/4, and 0/3 FL, respectively. All but 3/41 DLBCL were bcl-6+ with 17/37 also bcl-2+ and CD10+. Three of these cases were also CD138+. Twelve bcl-6+ cases were bcl-2+, CD10-, six bcl-2-, CD10+, and two bcl-2-, CD10-. The three bcl-6- cases were bcl-2+, CD138- and two were CD10+. Bcl-2R was identified in 5/27 DLBCL with 4/5 bcl-2+, 3/4 tested CD10+ and 4/4 bcl-6+. Bcl-6R was identified in 7/26 including three with a classic FL phenotype. The vast majority of DLBCL in this study have an immunophenotype that supports a FCC origin. Although the proportion of DLBCL that co-expressed bcl-6, CD10 and bcl-2 was lower than for the FL, absence of bcl-2 or CD10 may be associated with higher grade FL It is also possible that bcl-6 expression is not completely specific for a FCC origin. Only a minority of cases suggested postfollicular differentiation. Only a minority of DLBCL show bcl-2R, suggesting that many have a different molecular pathogenesis than most low-grade FL. Bcl-6R did not exclude a FCC origin.

De novo CD5+ diffuse large B-cell lymphomas. A heterogeneous group containing an unusual form of splenic lymphoma

We reviewed our institutional experience with de novo CD5+, large B-cell lymphomas to determine whether they represent a distinct entity and are related to CD5+ small B-cell disorders. We identified 13 cases with multiparameter flow cytometry over a period of 58 months (5% of large B-cell lymphomas) in 7 females and 6 males. Three groups were identified. Group 1 (2 cases) had diffuse splenic red pulp involvement with a distinctive cordal pattern of infiltration, no other clinical evidence of mass disease, microscopic disseminated disease on further workup, and an identical immunoglobulin-negative immunophenotype. Group 2 cases (7 cases) were clinically and morphologically heterogeneous and had an immunophenotype resembling mantle cell lymphoma (FMC7-positive, CD23-). Group 3 (4 cases) had miscellaneous immunophenotypes, including one closely resembling chronic lymphocytic leukemia. Cyclin D1 was positive in only 1 of 10 evaluable cases (group 2). We conclude that CD5+ diffuse large B-cell lymphomas are heterogeneous; most cases do not seem to be related to chronic lymphocytic leukemia or mantle cell lymphoma. However, we identified a subgroup of primary splenic CD5+ large B-cell lymphoma with diffuse red pulp involvement and believe this may represent a distinct clinicopathologic entity.