Different clonal origin of B-cell populations of chronic lymphocytic leukemia and large-cell lymphoma in Richter's syndrome

Prognostic Value of Accumulative Expression of COX-2 and p53 in Small and Diffuse Large B Cell Lymphoma

Cyclooxygenase-2 (COX-2) plays an important role in carcinogenesis, which catalyzes the conversion of arachidonic acid into prostaglandins. P53 is a tumor suppressor gene that contributes to apoptosis and cell cycle control. There is functional interaction between p53 and COX-2, which lead to abrogation of apoptosis and progression of malignancy. To assess the relationship between COX-2, p53 expression and the clinicopathololgic features in SLL and DLBCL. We immunohistochemically examined the expression of COX-2 and p53 in non-neoplastic lymphoid cells, lymph nodal low-grade (50 cases of SLL), intermediate and high-grade lymphomas (100 cases of DLBCL) and their corresponding bone marrow specimens. The expression of COX-2 and p53 was absent in the in non-neoplastic lymphoid cells. In contrast, their expression values increased progressively with the advancing grade of lymphoma (p < 0.001). COX-2 expression was significantly associated with advanced disease stage, high-grade lymphomas, and disease relapse and p53 expression. The p53was detected in 64.5% in patients positive for COX-2. The expressions of COX-2 and p53 proteins, were significantly associated with shorter overall-survival and progression free survival. Here we report up-regulation of COX-2and p53 protein expression in SLL and DLBCL indicating their interactive involvement in the pathogenesis of lymphoma. Our data provide a rationale for further investigation of COX-2 expression in lymphomas for potential prognostic, chemopreventive and chemotherapeutic purposes.

Second Malignancies and Richter's Syndrome in Patients with Chronic Lymphocytic Leukemia

Second malignancies are frequent complications in patients with chronic lymphocytic leukemia (CLL). Patients with this leukemia may develop large cell lymphoma (LCL) known as Richter's syndrome (RS). RS occurs in CLL patients of about 3% and may develop in a single lymph node or more often in a group of nodes. However, in some patients extranodal localization of aggressive lymphoma in RS has been observed. Besides LCL, Hodgkin's disease, prolymphocytoid leukemia, multiple myeloma and acute lymphoblastic leukemia may also occur as RS variants. The origin of lymphoid cells in RS remains tentative. However, CLL and RS originate from the same clone for some patients, whereas, in other patients cells of aggressive lymphoma do not have the features of the same clone as the CLL cells. The prognosis of RS is poor. Survival in different studies will be usually 2-5 months. The secondary development or coexistence of myeloproliferative disorders or myelodysplastic syndrome and solid tumors have also been rarely documented in CLL patients. It is of great concern that therapy may further increase the risk of a second neoplasm. However, until now, there are no clear evidence that alkylating agents or purine nucleoside analogs may be associated with an increased incidence of second malignancies in patients with CLL. In this review, epidemiology, biology, clinical characteristic and treatment approaches in RS and other secondary neoplasms in patients with CLL are discussed.

The basis and rational use of molecular genetic testing in mature B-cell lymphomas

An increasing number of neoplasms are associated with variably specific genetic abnormalities. This is best exemplified by hematological malignancies, in which there is a growing list of entities that are defined by their genetic lesion(s); this is not (yet) the case in mature B-cell lymphomas. However, enhanced insights into the pathogenesis of this large and diverse group of lymphomas have emerged with the ongoing unraveling of a plethora of fascinating genetic abnormalities. The purpose of this review is to synthesize well-recognized data and nascent discoveries in our understanding of the genetic basis of a spectrum of mature B-cell lymphomas, and how this may be applied to contemporary clinical practice. Despite the explosion of new and exciting knowledge in this arena, with the potential for enhanced diagnostic and prognostic strategies, it is essential to remain cognizant of the limitations (and complexity) of genetic investigations, so that assays can be developed and used both judiciously and rationally.

Clonal relationship between Hashimoto thyroiditis and thyroid lymphoma

BACKGROUND

Although Hashimoto thyroiditis (HT) is a predisposing factor for B-lineage thyroid lymphoma, clonal B-cell populations in HT are rare.

AIM

To investigate whether there is a clonal relationship between HT and primary thyroid lymphoma.

METHODS

Clonalilty and sequence similarity was determined by PCR followed by sequencing and comparing immunoglobulin heavy chain (IgH) gene rearrangement sequences to germline sequences and to each other.

RESULTS

12/20 patients with primary thyroid lymphoma had a previous history and histological diagnosis of HT. Clonal IgH bands associated with a polyclonal background were present in four of these 12 cases of HT; of these four, three had reproducible clonal IgH bands from the subsequently developed lymphoma. The range of similarity (homology) of multiple clonal bands in HT with the germline IgH varied from 90% to 96.3%. Multiple clonal bands in HT had sequence similarity (homology) of 62-100% with the clonal band in the lymphoma from the same patient. At least one clonal band in HT had more than 96% similarity (homology) with the clonal band of lymphoma in all three cases.

CONCLUSION

Sequence similarity between the clonal bands in HT and subsequently developed thyroid lymphoma is supportive of the argument that primary thyroid lymphoma may evolve from HT.

A Common Clonal Origin of Nodal Marginal Zone B-Cell Lymphoma and Plasma Cell Myeloma Demonstrating Different Immunophenotypes

We demonstrated an 83-year-old male case of composite lymphoma. Before 18 years, he was diagnosed with nodal marginal zone B-cell lymphoma in the cervical lymph node. Peripheral blood showed anemia and IgA (kappa)-type monoclonal gammopathy (IgA; 3,625 mg/dL). Bone marrow aspiration biopsy exhibited plasma cell myeloma, in which atypical plasma cells were positive for cytoplasmic IgA (kappa) and atypical lymphoid cells intermingled were positive for CD20. In contrast, cervical lymph node biopsy revealed nodal marginal zone B-cell lymphoma, in which lymphoma cells were positive for cytoplasmic IgG (lambda). Southern blotting analysis of the IgH gene showed same clonal rearrangement band in both lymph node and bone marrow samples and additional band in the bone marrow. Sequence analyses of the IgH gene showed an identical sequence of CDR3 in both samples. Thus, we demonstrated a common clonal origin of composite lymphoma comprising nodal marginal zone B-cell lymphoma and plasma cell myeloma. Nodal marginal zone B-cell lymphoma recurred in cervical lymph node and involved into the bone marrow, differentiating into plasma cell myeloma in which Ig isotype switched and monoclonal gammopathy developed. Sequence analysis of the IgH gene was a powerful tool for determination of clonal origin.

Richter syndrome in B-cell chronic lymphocytic leukemia

Richter syndrome (RS) is well known as a secondary high-grade lymphoma, mostly diffuse large B-cell lymphoma (DLBCL) developed in patients with B-cell chronic lymphocytic leukemia (B-CLL). In this review, we describe clinicopathological, histological, immunophenotypical and genetic findings of RS. The patients with RS, regardless of transformation of pre-existing clone or de novo malignant clone, were resistant to conventional combined chemotherapy and died within months of diagnosis. Molecular techniques can provide convincing results for the clonal relationship of RS to pre-existing B-CLL. When RS carries a same rearrangement band or a same sequence as B-CLL by Southern blotting or nucleotide sequence analyses of immunoglobulin heavy and/or light chain genes, it is suggested to that RS transforms from original B-CLL. These analyses have showed that approximately two-thirds of RS cases evolved from a B-CLL clone. How and where does the B-CLL clone evolve to RS? The genetic alteration of transforming B-CLL clone into RS has been addressed. Abnormalities of chromosomes 11 and 14 were most frequently involved in RS, but non-specific. In addition, RS does not include chromosomal translocation between Ig locus and oncogenes or rearrangements of bcl-6 gene, both of which were found in some de novo DLBCL. Several candidates, such as mutation of p53 gene and abnormalities of cyclin dependent kinase inhibitor, have been proposed to play an important role in the transformation of a part of B-CLL. However, there is still uncertainty as to how B-CLL progresses or develops into RS.

Biclonality of gastric lymphomas

The pathogenesis and clonal evolution of gastric diffuse large B-cell lymphoma (DLBCL) and its relationship to extranodal marginal zone B-cell lymphoma (MZBL), mucosa-associated lymphoid tissue (MALT) type, are still controversial. The aim of this study was to establish the clonality of morphologically distinct areas of gastric lymphomas as well as their genetic relationship to each other. Six gastric lymphomas, consisting of two MZBL, MALT type, two DLBCL, and two "composite" lymphomas were subjected to laser capture microdissection and subsequent PCR-based amplification of the immunoglobulin heavy chain gene. One DLBCL showed a biclonal pattern of rearranged immunoglobulin heavy chain (IgH) genes of two different areas without evidence of a common origin. Two composite DLBCL with areas of extranodal MZBL, MALT type, were also biclonal and displayed different IgH gene rearrangements in the small-cell and in the large-cell components, respectively. Sequencing of the CDR3 region revealed unique VH-N-D and D-N-JH junctions, thus corroborating the presence of two genuinely distinct tumor clones in each of these three cases. In contrast, the remaining three gastric lymphomas (one DLBCL and two MZBL, MALT type) showed IgH gene rearrangements in which CDR3 regions were identical in the different tumor areas. Our results suggest that gastric DLBCL may be composed of more than one tumor cell clone. Further, DLBCL may not necessarily evolve by transformation of a low-grade lymphoma, but may also originate de novo. An ongoing emergence of new tumor clones may considerably hamper molecular diagnosis and follow-up of gastric DLBCL.

High-grade T-cell lymphoma complicating B-cell chronic lymphocytic leukemia: an unusual manifestation of "Richter's syndrome"

Approximately 3% of patients with B-cell chronic lymphocytic leukemia (CLL) develop a high-grade large-cell lymphoma consistent with Richter's Syndrome. In most cases, these lymphomas are of B-cell origin and are believed to arise by clonal evolution from the CLL cells. We present a case of a patient with a 10-year history of B-CLL who developed an aggressive large-cell lymphoma, confirmed by immunophenotype to be of T-cell origin. We suggest that in patients with CLL, immunodysregulation can result in the proliferation of T cells, which may mutate and result in the development of a new malignant clone.

High-grade transformation of low-grade non-Hodgkin's lymphomas: mechanisms of tumor progression

In the natural history of low-grade non-Hodgkin's lymphomas (NHL) a prolonged indolent phase of the disease may be followed by clinical progression toward intermediate and high-grade disease. The abrupt appearance of diffuse large cell lymphoma (DLL) in patients with low-grade NHL is usually associated with an accelerated clinical course and shorter time of survival. The histologic transformation has been described for chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL), follicular lymphoma (FL), mantle cell lymphoma (MCL) and lymphoma of mucosa-associated lymphoid tissue (MALT). Although the histological transformation of low-grade lymphomas are relatively frequent, the clonal relationship between the two neoplasms and pathogenetic mechanisms underlying the progression of the disease are widely debated. In this review, we will focus on the possible relationship between the low-grade and the transformed high-grade NHLs and genetic lesions that may be associated with the histologic transformation and clinical progression of the disease.

Distinct clonal origin of low-grade MALT-type and high-grade lesions of a multifocal gastric lymphoma

AIMS

Low-grade mucosa-associated lymphoid tissue (MALT) lymphoma and high-grade B-cell non-Hodgkin's lymphoma (NHL) of the stomach may occur simultaneously. To determine the clonal relationship between these tumours, we compared the immunoglobulin heavy chain gene (IgH) rearrangements of low and high-grade components of a multifocal gastric NHL.

METHODS AND RESULTS

The complementary determining region 3 (CDR3) of the IgH gene rearrangements were polymerase chain reaction (PCR) amplified, cloned and sequenced. The analysis of the CDR3 sequences rearranged by tumour cells of low-grade MALT and the high-grade NHL revealed different nucleic acid sequences.

CONCLUSION

These findings suggest that low-grade MALT and high-grade B-cell components of multifocal gastric NHL may represent unrelated clones.