The molecular biology of B-cell lymphoma: clinicopathologic implications

Primary cutaneous B-cell lymphomas: a practical approach

PCBCL are a heterogeneous group of B-cell lymphomas that originate in the skin, with the absence of extracutaneous disease at diagnosis. Overall, these cutaneous lymphomas have an excellent prognosis. Recurrences are common but dissemination is rare. The EORTC classification allows a more uniform diagnosis and treatment of patients with PCBCL. Careful clinical and pathologic correlation is critical in confirming a diagnosis of PCBCL, before deciding on therapy. Several therapeutic options that are aimed at cure, are available. In most instances, chemotherapy should not be the first line of treatment.

Comparative genomic hybridization analysis of primary cutaneous B-cell lymphomas: identification of common genomic alterations in disease pathogenesis

To investigate genetic alterations in primary cutaneous B-cell lymphomas (PCBCLs), we have analyzed 29 cases of PCBCL. Comparative genomic hybridization showed chromosome imbalances (CIs) in 12 cases (41%). The mean number of CIs per sample was 2.05 +/- 2.97, with gains (1.48 +/- 2.38) more frequent than losses (0.56 +/- 1.40). The common regions of gains were 18/18q (50%), 7/7p (42%), 3/3q (33%), 20 (33%), 1p (25%), 12/12q (25%), and 13/13q (25%), whereas loss of 6q was frequent (42%). Among the different subsets of PCBCLs, CI was seen in 50% of diffuse large-cell lymphomas (DLCLs), 33% of marginal zone lymphomas, and 8% of follicle center cell lymphomas and unclassified lymphomas. A similar pattern of CI was observed in these lymphomas, but loss of 6q and gains of 3/3q were present only in DLCLs. Microarray-based genomic analysis of four DLCL cases identified oncogene gains of SAS/CDK4 (12q13.3) in three cases and MYCL1 (1p34.3), MYC (8q24), FGFR2 (10q26), BCL2 (18q21.3), CSE1L (20q13), and PDGFB (22q12-13) in two cases, whereas losses of AKT1 (14q32.3), IGFR1 (15q25-26), and JUNB (19p13.2) were identified in three cases, and losses of FGR (1p36), ESR (6q25.1), ABL1 (9q34.1), TOP2A (17q21-22), ERBB2 (17q21.2), CCNE1 (19q13.1), and BCR (22q11) were each identified in two cases. In addition, real-time-polymerase chain reaction detected amplification of BCL2 in 5 of 29 cases. These findings suggest that there are complex but consistent genetic alterations associated with the pathogenesis of PCBCLs.

Primary cutaneous B-cell lymphoma: review and current concepts

PURPOSE

Primary cutaneous B-cell lymphoma (PCBCL) has only recently been recognized as a distinct clinical entity. With the advent of improved immunophenotyping and immunogenotyping, increasing numbers of PCBCL cases are being diagnosed. However, there is much confusion regarding the classification, treatment, and prognosis of these patients. The purpose of this article is to review and analyze the available data to provide the clinician with a concise summary of the diagnosis, prognosis, and treatment of PCBCL.

DESIGN

We conducted a thorough review of the medical literature on PCBCL, with a focus on classification, prognosis, and treatment trials.

RESULTS AND CONCLUSION

PCBCL is defined as a B-cell lymphoma originating in the skin. There is no evidence of extracutaneous disease at presentation and for 6 months after diagnosis, as assessed by adequate staging procedures. Currently, the European Organization for Research and Treatment of Cancer classification is the most concise disease classification scheme, dividing the subtypes of PCBCL by clinical behavior and histopathologic findings. Based on this classification, the most common subtype of PCBCL is follicular center cell lymphoma. PCBCL is generally an indolent form of lymphoma with a good prognosis. Although local cutaneous recurrences are observed in 25% to 68% of patients, dissemination to internal organs is rare. Five-year survival rates typically range from 89% to 96%. A specific subtype, large B-cell lymphoma of the leg, is noted to have a poorer prognosis, with a 5-year survival rate of 58%. Overly aggressive treatment of PCBCL has not been shown to improve survival or prevent relapse. The treatment of choice usually varies depending on the type of PCBCL, the body surface area, and the location of the involvement, as well as the age and general health condition of the patient. The majority of studies indicate that PCBCL is highly responsive to radiation therapy. Polychemotherapy should be reserved for involvement of noncontiguous anatomic sites or those with extracutaneous spread.

Z-138: a new mature B-cell acute lymphoblastic leukemia cell line from a patient with transformed chronic lymphocytic leukemia

We describe a new mature B-cell acute lymphoblastic leukemia (ALL) cell line designated Z-138 that was derived from a patient with chronic lymphocytic leukemia (CLL) whose disease underwent transformation to a rare, aggressive form of mature B-cell ALL. This cell line has an L3 morphology, ultrastructural characteristics of lymphoblasts, B-lineage surface markers and an immunoglobulin heavy-chain gene rearrangement identical to the rearrangement observed in the patient's blasts from whom the cell line was derived. Z-138 cells produce granulocyte-macrophage colony-stimulating factor (GM-CSF) and high levels of granulocyte-CSF (G-CSF), but they do not exhibit a proliferative response to either cytokine. Both the patient's lymphoblasts and Z-138 cells exhibited cytogenetic abnormalities including t(8;14), t(14;18) and a chromosome 11 abnormality similar to the t(11;14) of the parental cells, resulting in marked overexpression of cyclin D1 (BCL-1 (PRAD1)) mRNA in Z-138 cells. Since these karyotypic anomalies have been associated with low grade (t(14;18)), intermediate grade (t(11;14)) and high grade (t(8;14)) lymphomas, their development may be involved in the unusual aggressive transformation of this patient's CLL.

Extracellular matrix and beta 1 integrin expression in nodal and extranodal T-cell lymphomas

Since non-Hodgkin's lymphoma (NHL) cells interact with surrounding structures similarly to their normal counterparts, micro-environmental changes and the aberrant expression of adhesion molecules are considered to be of importance in lymphomagenesis. In this immunohistochemical study, the composition of several extracellular matrix (ECM) components and the expression of their beta 1 integrin receptors were examined in nodal and extranodal T-cell NHLs. Except for the T-lymphoblastic NHLs, almost all T-NHLs displayed abundant deposition of matrix and considerable expression of the alpha 4 and beta 1 integrin chains. This is in contrast to B-cell NHLs, which show ECM patterns comparable to those in reactive lymphoid tissue or, in cases of high-grade malignancy, active matrix degradation and very low expression or absence of beta 1 integrins, as previously described. This difference is probably based on distinct cytokine production in B- and T-cell malignancies. As in B-NHL, nodal and extranodal T-NHLs of the same morphological subtype exhibit identical ECM patterns, which suggests that malignant lymphoid cells of both B and T origin create at least part of their own specific micro-environment.

Distribution of extracellular matrix components and their receptors in human lymphoid tissue and B-cell non-Hodgkin lymphomas

In this study the distribution patterns of various extracellular matrix components and their receptors (i.e. beta 1 integrins) in B-cell non-Hodgkin lymphomas were examined and compared to those in reactive lymphoid tissue. Neoplastic follicles within follicular lymphomas showed similar patterns to that observed in reactive follicles, which appeared to be strongly associated with the presence of follicular dendritic cells. Diffuse lymphomas of low and intermediate malignancy grade revealed features comparable to those of interfollicular areas of reactive lymphoid tissue, irrespective to which compartment the tumour cells were related. Highly malignant lymphomas, however, displayed unique extracellular matrix configurations, resulting from active matrix degradation by macrophages; this may support rapid tumour growth. Extranodal lymphomas showed virtually the same matrix patterns as their nodal counterparts, suggesting that (malignant) lymphoid cells generate (at least partly) their own specific microenvironment. In reactive lymphoid tissue beta 1 integrins were mainly found on resident cells and except for alpha 4, alpha 5 (and beta 1) the lymphoid cells expressed very little, if any, beta 1 integrins. In comparison, expression of these integrins on lymphoma cells was reduced (follicular lymphomas) or could not be detected at all (diffusely growing lymphomas); this might contribute to the growth pattern and metastatic properties of the tumours.

bcl-2 protein expression and correlation with the interchromosomal 14;18 translocation in cutaneous lymphomas and pseudolymphomas

The interchromosomal 14;18 translocation occurs in approximately 70-80% of follicular lymphomas and in a lower proportion of high-grade non-Hodgkin lymphomas of the lymph nodes. This translocation results in the fusion of the bcl-2 oncogene on chromosome 18 with immunoglobulin heavy chain genes on chromosome 14, and in the expression of higher amounts of normal bcl-2 protein. We studied bcl-2 expression in biopsies of 108 patients with benign and malignant cutaneous lymphoproliferative diseases (B-cell lymphoma, primary cutaneous, 42; secondary cutaneous, 21; primary cutaneous T-cell lymphoma, 21; B-cell pseudolymphoma, 24), using a monoclonal anti-bcl-2 antibody on paraffin-embedded tissue sections, bcl-2 protein was detected immunohistochemically in 16 of 63 cases of cutaneous B-cell lymphoma, whereas cutaneous T-cell lymphomas and B-cell pseudolymphomas were negative. The proportion of bcl-2 protein expression was significantly higher in secondary (11/21) than in primary cutaneous B-cell lymphomas (5/42; chi 2 test, p < 0.001). Biopsies from 25 of these patients (B-cell lymphoma, 22; B-cell pseudolymphoma, three) were analyzed previously on the molecular level for the t(14;18), using polymerase chain reaction amplification of DNA obtained from paraffin-embedded sections. In four of 11 cases of bcl-2 protein-positive B-cell lymphoma (primary, one; secondary, three) the t(14;18) was detected by polymerase chain reaction. All other cases of B-cell lymphoma, including seven cases where bcl-2 protein was detected by immunohistology, and B-cell pseudolymphoma were negative. These results demonstrate: 1) bcl-2 protein is expressed in a small portion of cutaneous B-cell lymphomas; 2) bcl-2 protein expression is significantly more frequent in secondary than in primary cutaneous B-cell lymphoma; 3) only approximately one-third of cases expressing the bcl-2 protein are characterized also by the t(14;18). bcl-2 protein expression might indicate that the cutaneous manifestation of the lymphoma represents a secondary spread from a node-based lymphoma.

Ocular adnexal lymphoproliferative lesions

Ocular adnexal lymphoproliferative lesions consist of a spectrum of disease entities, including reactive lymphoid hyperplasia, atypical lymphoid hyperplasia, and lymphoma. No clinical or radiologic criteria facilitate a distinction among these lymphoproliferative lesions. The two hyperplastic processes may evolve to localized or systemic lymphoma. A similar pattern is evident in other mucosa-associated lymphoid tumors elsewhere in the body. Most ocular adnexal lymphomas are small lymphocytic non-Hodgkin's tumors with an indolent course; frequently, they remain localized to the ocular adnexa. In comparison, intermediate- and high-grade lymphomas are less common in the ocular adnexa but more aggressive. An approach to the diagnosis and treatment of these complex entities is suggested. Despite new pathologic classification schemes, immunophenotypic labeling, and molecular genetic analysis, the prognosis for patients with small-cell lymphoma in the ocular adnexa is difficult to predict.

Analysis of the 14;18 translocation in cutaneous lymphomas using the polymerase chain reaction

A series of 25 cutaneous B-cell lymphoid proliferations was analyzed for the presence of the (14; 18) translocation using the polymerase chain reaction. Junctional sequences of rearranged chromosomes 14 and 18 were amplified in vitro, and t (14; 18) specific sequences were detected in 1 of 14 primary cutaneous B-cell lymphomas, in 3 of 8 primary nodal B-cell lymphomas and in none of 3 B-cell pseudolymphomas. These results indicate that the t (14; 18) may occur in a small subset of primary cutaneous lymphoma. However, the difference in incidence of the t (14; 18) between primary nodal and primary cutaneous lymphomas suggests that different molecular mechanisms are involved in the pathogenesis of these lymphomas.

Translocation t(11;14)(q13;q32) in chronic lymphoid disorders

The translocation t(11;14)(q13;q32) has been described in a spectrum of B-lymphoproliferative diseases and involves a putative oncogene, BCL1, which maps to chromosome band 11q13. Recent evidence indicates that this abnormality may delineate particular subtypes of lymphoma, such as intermediate lymphocytic and centrocytic lymphomas. Thus the possible significance of the t(11;14) within B-cell disorders should be reexamined in the light of a more objective approach to classifying these diseases by morphology, histology, and immunophenotype. We describe 16 patients with t(11;14)(q13;q32) from a series of 90 patients with chronic lymphoid disorders in whom clonal chromosome abnormalities were detected. All the cases were leukemic: prolymphocytic (B-PLL; 4/15 cases), chronic lymphocytic leukemia (CLL) with increase in prolymphocytes (2/9 cases), or non-Hodgkin lymphoma in leukemic phase, intermediate (3/4 cases), lymphoplasmacytic (2/2 cases), splenic lymphoma with villous lymphocytes (4/18 cases), and follicular (1 case). None of the CLL (25) or hairy cell leukemia cases (15) had t(11;14). Our findings showed that t(11;14) occurred in leukemias of mature B cells with lymphoplasmacytic features as judged by morphology and immunophenotype.