CD5 negative and CD5 positive splenic marginal B-cell lymphomas have differential cytogenetic patterns

Prognostic significance of aberrant CD5 expression in B-cell leukemia

Aberrant expression of CD5 (as a T-cell marker) is seen in some leukemia and lymphoma of B lineage origin. Given that the signaling resulting from the expression of this marker plays an essential role in the development of leukemia and lymphoma, evaluating the expression of this marker is of paramount importance. Therefore, our goal in this study was to investigate the prognostic importance of CD5 expression in B-cell leukemia and lymphoma. We evaluate CD5 expression in normal and leukemic B-cells by identifying relevant literature through a PubMed search (1998-2018) of English language papers using the terms: ‘CD5,’ ‘B-cell,’ ‘Leukemia,’ and ‘Lymphoma.’ We are doing this thorough comparison of results from CD5 positive and negative cases to make a correct decision about prognostic importance of CD5 expression in these malignancies. In a number of B-cell malignancies, CD5 is expressed in varying degrees. Due to the different origins and characteristics of these malignancies, the results of CD5 expression evaluations are heterogeneous and impossible to generalize. However, CD5 expression is sometimes associated with clinicopathologic findings, more invasive clinical course, and even resistance to treatment (specifically in DLBCL) among CD5- positive patients, which appears to be a function of CD5 signaling and its downstream factors such as STAT3. Depending on the type of malignancy, CD5 expression is associated with good or bad prognosis, which can be used as an auxiliary prognostic factor to assess the clinical course of B-cell malignancies. Moreover, the difference in expression levels of CD5 in a variety of B-cell malignancies allows for differential diagnosis of these malignancies, which can be helpful when diagnosis is difficult.

Diagnostic Algorithm of Common Mature B-Cell Lymphomas by Immunohistochemistry

CONTEXT

- Different types of mature B-cell lymphomas, including plasma cell neoplasms, exhibit distinct immunohistochemical profiles, which enable them to be correctly diagnosed. However, except for rare examples of lymphoma-specific immunohistochemistry, such as cyclin D1 in mantle cell lymphoma and annexin A1 in hairy cell leukemia, immunohistochemical profiles of mature B-cell lymphomas overlap and lack specificity.

OBJECTIVES

- To systemically review immunohistochemical features associated with commonly encountered mature B-cell lymphomas based on the presence or absence of CD5 and CD10; to review the immunophenotypic profile of plasma cells derived from plasma cell myelomas and B-cell lymphomas; and to review a group of rare, aggressive B-cell lymphomas with antigen expression features of plasma cells.

DATA SOURCES

- Published and PubMed-indexed English literature was reviewed.

CONCLUSIONS

- Although the presence or absence of CD5 and CD10 expression should be included in the initial immunohistochemistry screening panel for mature B-cell lymphomas, appropriate and judicial use of other B-cell antigens is necessary to ensure correct diagnoses. Furthermore, although the status of CD5 and CD10 expression is associated with certain prototypes of B-cell lymphomas, their expression is not specific. Plasma cells from plasma cell neoplasias and B-cell lymphomas exhibit overlapping but relatively distinct immunophenotypes; thus, a panel of immunohistochemical markers (CD19, CD45, CD56, and CD117) can be employed for their proper identification. Lastly, CD138 staining results are almost always positive in a group of aggressive B-cell lymphomas with plasmablastic features, including plasmablastic plasma cell myeloma, plasmablastic lymphoma, and ALK-1⁺ large B-cell lymphoma.

Diagnostic and clinical considerations in concomitant bone marrow involvement by plasma cell myeloma and chronic lymphocytic leukemia/monoclonal B-cell lymphocytosis: a series of 15 cases and review of literature

CONTEXT

Plasma cell myeloma and chronic lymphocytic leukemia are both common hematologic malignancies, sharing many epidemiologic features. Concomitant detection of the 2 conditions poses special diagnostic challenges for the pathologist.

OBJECTIVE

To describe the pathologic findings in cases of concomitant bone marrow involvement by myeloma and CD5(+) monoclonal B cells and to outline the differential diagnostic possibilities, suggest a workup for correct diagnosis, and examine clinical outcome.

DESIGN

Fifteen cases that met the diagnostic criteria were identified from pathology databases at 4 participating institutions. Morphologic findings were reviewed, additional immunohistochemical stains performed, and flow cytometric, cytogenetic, and relevant laboratory and clinical information was summarized. Previously published cases were searched from electronic databases and cross-references.

RESULTS

Most patients (13 of 15) were older males. Often (11 of 15) they presented clinically with myeloma, yet had both monotypic plasma cells and B cells in the diagnostic marrow. In 4 patients, myeloma developed 24 months or later after chronic lymphocytic leukemia. In 7 patients, myeloma and CD5(+) B cells showed identical immunoglobulin light-chain restriction. Primary differential diagnoses include lymphoplasmacytic lymphoma, marginal zone lymphoma, and chronic lymphocytic leukemia with plasmacytoid differentiation. CD56 and/or cyclin D1 expression by plasma cells was helpful for correct diagnosis. Most patients in our cohort and published reports were treated for plasma cell myeloma.

CONCLUSIONS

Concomitant detection of myeloma and chronic lymphocytic leukemia in the bone marrow is a rare event, which must be carefully differentiated from lymphomas with lymphoplasmacytic differentiation for correct treatment.

Cytogenetic aberrations and their prognostic value in a series of 330 splenic marginal zone B-cell lymphomas: a multicenter study of the Splenic B-Cell Lymphoma Group

We conducted a retrospective collaborative study to cytogenetically characterize splenic marginal zone lymphoma (SMZL) and ascertain the prognostic value of chromosomal aberrations. Of 330 cases, 72% displayed an aberrant karyotype, 53% were complex, and 29% had a single aberration. The predominant aberrations were gains of 3/3q and 12q, deletions of 7q and 6q and translocations involving 8q/1q/14q. CD5 expression was detected in 39 of 158 cases (25%). The cytogenetic makeup of the CD5+ group differed significantly from that of the CD5− group. Cases with unmutated IGHV were significantly associated with deletions of 7q and TP53. A strong association was noted between usage of the IGVH1-2 and deletion 7q, 14q alterations, and abnormal karyotype. On univariate analysis, patients with more than or equal to 2 aberrations, 14q alterations, and TP53 deletions had the shortest survival; 7q deletion did not affect survival. On multivariate analysis, cytogenetic aberrations did not retain prognostic significance; the parameters negatively affecting survival were hemoglobin and age. In conclusion, the cytogenetic profile of SMZL is distinct from other B-cell lymphomas. Complexity of the karyotype, 14q aberrations, and TP53 deletions are poor prognostic indicators and may be considered together with other clinicobiologic parameters to ascertain the prognosis of SMZL.

CD5 expression identifies a subset of splenic marginal zone lymphomas with higher lymphocytosis: a clinico-pathological, cytogenetic and molecular study of 24 cases

BACKGROUND

Classically, splenic marginal zone B-cell lymphoma is characterized by the absence of CD5 expression. Cases of apparent splenic marginal zone B-cell lymphoma showing CD5 expression, as diagnosed by blood studies, have been described; however, in the absence of histological evidence, the correct diagnosis of these cases is controversial because of possible confusion with other CD5-positive small B-cell neoplasms.

DESIGN AND METHODS

We report a series of 24 CD5-positive, t(11;14)-negative cases of splenic marginal zone B-cell lymphoma diagnosed by flow cytometry studies of blood and histologically proven on spleen sections. Clinical data as well as morphological, immunological, cytogenetic and molecular characteristics were assessed to evaluate the similarities and differences of these cases with those of classical CD5-negative splenic marginal zone B-cell lymphoma.

RESULTS

The CD5 expression detected in blood by flow cytometry was confirmed in most cases by immunohistochemistry on spleen sections. In general, cases of CD5-positive and CD5-negative splenic marginal zone B-cell lymphoma did not appear different and, in particular, they showed similar karyotypic changes such as 7q deletion, trisomy 3, trisomy 18 and biased IGHV usage (i.e. VH1-2). The main differences were a higher lymphocyte count at diagnosis (8.15x10(9)/L versus 3.90x10(9)/L; P=0.005) and more frequent diffuse bone marrow infiltration (34% versus 8%; P=0.03) in the CD5-positive group. A tendency to a more mutated IGHV status in the CD5 positive cases was observed (80% versus 54.5%; (P=0.11). No significant differences in outcome were found in relation to CD5 expression.

CONCLUSIONS

This study confirms the existence of cases of CD5-positive splenic marginal zone B-cell lymphoma and shows that these cases are closely related to classical splenic marginal zone lymphoma. Whether or not CD5-positive splenic marginal zone B-cell lymphoma constitutes a true subset obviously requires the study of more cases.

Clinicopathologic features of CDK6 translocation-associated B-cell lymphoproliferative disorders

Cyclin-dependent protein kinase 6 (CDK6), in cooperation with cyclin Ds, drives cell cycle progression from G1 to S phase through phosphorylation and subsequent inactivation of retinoblastoma 1 protein. Alteration of this pathway results in both nonhematologic and hematologic malignancies, which include a small subset of B-cell lymphoproliferative disorders (BLPDs). We identified 5 cases of BLPD that carried CDK6 chromosomal translocations and characterized their clinical, pathologic, immunophenotypic, and genetic features. Common clinical characteristics included marked neoplastic lymphocytosis, systemic lymphadenopathy, splenomegaly, and bone marrow involvement. Three patients were diagnosed with low-grade B-cell lymphoma and had an indolent clinical course, and 2 patients (one who transformed to large B-cell lymphoma, and the other who was initially diagnosed with a high-grade B-cell lymphoma) had an aggressive clinical course. Immunophenotypically, the neoplastic B cells expressed CD5, CDK6, and cytoplasmic retinoblastoma 1 protein in all cases, expressed phospho-RB, p27kip1, and cyclin D2 in most cases, and uniformly lacked expression of all other cyclins. In 4 cases, the CDK6 translocation partner was kappa immunoglobulin light-chain gene; and in the fifth case, the CDK6 translocation partner was unknown. These distinct clinicopathologic and cytogenetic features distinguish the CDK6 translocation-associated BLPDs (CDK6-BLPDs) from other mature B-cell lymphomas.