Immunophenotype does not correlate with lymph node histology in chronic lymphocytic leukemia/small lymphocytic lymphoma

Dysregulation of PRMT5 in chronic lymphocytic leukemia promotes progression with high risk of Richter's transformation

Richter's Transformation (RT) is a poorly understood and fatal progression of chronic lymphocytic leukemia (CLL) manifesting histologically as diffuse large B-cell lymphoma. Protein arginine methyltransferase 5 (PRMT5) is implicated in lymphomagenesis, but its role in CLL or RT progression is unknown. We demonstrate herein that tumors uniformly overexpress PRMT5 in patients with progression to RT. Furthermore, mice with B-specific overexpression of hPRMT5 develop a B-lymphoid expansion with increased risk of death, and Eµ-PRMT5/TCL1 double transgenic mice develop a highly aggressive disease with transformation that histologically resembles RT; where large-scale transcriptional profiling identifies oncogenic pathways mediating PRMT5-driven disease progression. Lastly, we report the development of a SAM-competitive PRMT5 inhibitor, PRT382, with exclusive selectivity and optimal in vitro and in vivo activity compared to available PRMT5 inhibitors. Taken together, the discovery that PRMT5 drives oncogenic pathways promoting RT provides a compelling rationale for clinical investigation of PRMT5 inhibitors such as PRT382 in aggressive CLL/RT cases.

Recurrent Chromosomal Abnormalities in Tissues Involved by Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

OBJECTIVES

Prognostically relevant chromosomal abnormalities in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) are routinely identified by fluorescence in situ hybridization (FISH) on peripheral blood or bone marrow specimens. We studied the prevalence of chromosomal abnormalities on extramedullary tissues involved by CLL/SLL and evaluated their association with prominent proliferation centers (PPCs).

METHODS

FISH for recurrent abnormalities in CLL/SLL was performed on formalin-fixed, paraffin-embedded biopsy sections. PPCs were identified on H&E-stained sections. Available FISH results on peripheral blood or bone marrow specimens were also reviewed.

RESULTS

Recurrent FISH abnormalities were detected in 69% of 320 CLL/SLL biopsy specimens studied, including +12 (35%), 13q- (24%), 11q- (15%), 17p- (6%), 6q- (2%), and IGH/BCL2 (0.9%). Forty-three patients had abnormal blood or bone marrow FISH analyses, of whom 7 (16%) had discordant +12 and/or 13q-, and 3 (7%) had discordant 17p- or 11q-. Morphology was positive (17%), negative (78%), or equivocal (6%) for PPCs on 247 evaluable biopsy specimens, a finding not significantly associated with FISH results (P = .7).

CONCLUSIONS

Trisomy 12 is overrepresented in tumoral CLL/SLL involvement, compared with the known predominance of 13q- in blood. Discrepancies between leukemic and tissue FISH findings are occasionally encountered. FISH results do not correlate with the presence of PPCs.

Hodgkin Reed-Sternberg-Like Cells in Non-Hodgkin Lymphoma

Reed-Sternberg cells (RSCs) are hallmarks of classic Hodgkin lymphoma (cHL). However, cells with a similar morphology and immunophenotype, so-called Reed-Sternberg-like cells (RSLCs), are occasionally seen in both B cell and T cell non-Hodgkin Lymphomas (NHLs). In NHLs, RSLCs are usually present as scattered elements or in small clusters, and the typical background microenviroment of cHL is usually absent. Nevertheless, in NHLs, the phenotype of RSLCs is very similar to typical RSCs, staining positive for CD30 and EBV, and often for B cell lineage markers, and negative for CD45/LCA. Due to different therapeutic approaches and prognostication, it is mandatory to distinguish between cHL and NHLs. Herein, NHL types in which RSLCs can be detected along with clinicopathological correlation are described. Moreover, the main helpful clues in the differential diagnosis with cHL are summarized.

B-cell neoplasms and Hodgkin lymphoma in the spleen

B-cell lymphoma of spleen may be primary (most commonly splenic diffuse large B-cell lymphoma) or secondary (typically low-grade non-Hodgkin lymphoma). Depending on the specific lymphoma subtype, there may be a predominantly white pulp pattern of involvement, a predominantly red pulp pattern or a focal nodular pattern. Splenectomy is the ideal specimen for a multiparametric integrative diagnosis of splenic lymphoma, as it allows for a combined study of morphology, immunohistology, flow cytometry, cytogenetics, and molecular genetic techniques. This review article describes the clinicopathologic characteristics of all the relevant B-cell neoplasms that may be encountered in a splenic biopsy or a splenectomy specimen.

TP53 Staining in Tissue Samples of Chronic Lymphocytic Lymphoma Cases: An Immunohistochemical Survey of 51 Cases

Objective:

Chronic lymphocytic leukemia (CLL) is the most common lymphoproliferative disease in adults. The aim of this study is to find out if the extent of proliferation centers or the immunohistochemical expression of p53 is related to disease prognosis.

Materials and Methods:

In the scope of this study, 54 biopsy specimens from 51 patients (50 of lymph nodes; the others of spleen, tonsil, orbit, and liver) diagnosed with CLL at the Hacettepe University Department of Pathology in 2000-2013 were reevaluated. The clinical and demographic data of the patients were obtained from our patient database. Biopsy samples were assessed semi-quantitatively for the percentage of proliferation center/total biopsy area (PC/TBA) and an immunohistochemical study was performed on representative blocks of tissues for p53 expression.

Results:

When the patients were divided into two categories according to Rai stage as high and low (stages 0, 1, and 2 vs. stages 3 and 4), it was seen that patients with low Rai stage had a better prognosis than those with high stages (p=0.030). However, there was no statistically significant correlation between overall survival and PC/TBA ratio or p53 expression levels.

Conclusion:

In our cohort, PC/TBA ratio and immunopositivity of p53 did not show correlations with overall survival.

Possible role of CD22, CD79b and CD20 expression in distinguishing small lymphocytic lymphoma from chronic lymphocytic leukemia

Aim of the study

Flow cytometry has an important role in diagnosis and classification of B-cell lymphoproliferative disorders (BCLPDs). However, in distinguishing chronic lymphocytic leukemia (CLL) from small lymphocytic lymphoma (SLL) only clinical criteria are available so far. Aim of the study was to determine differences in the expression of common B cell markers (CD22, CD79b and CD20) on the malignant lymphocytes in the peripheral blood samples of CLL and SLL patients.

Material and methods

Peripheral blood samples of 56 CLL and 11 SLL patients were analyzed by 5-color flow cytometry on the CD45/CD19/CD5 gate for CD22, CD79b and CD20.

Results

In the samples collected from the CLL patients, CD22 expression was detected in only 20% of patients in the low pattern, while in SLL patients the expression was medium and present in 90.9% of patients (p < 0.0001). For CD79b expression, statistical significance is reached both in the expression pattern, which was low/medium for CLL and high for SLL, and expression level (p = 0.006). The expression of CD20 was counted as the CD20/CD19 ratio. The average ratio was 0.512 in the CLL patients vs. 0.931 in the SLL patients (p = 0.0001).

Conclusions

The pattern of expression and expression level of CD22, CD79b and CD20 in peripheral blood could be used for distinguishing SLL from CLL patients.

Hsa-miR-15a and Hsa-miR-16-1 expression is not related to proliferation centers abundance and other prognostic factors in chronic lymphocytic leukemia

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) is the commonest leukemia in adults. Here, we aimed to evaluate hsa-miR-15a/hsa-miR-16-1 expression in CLL tissues by qPCR and correlate it with the other clinicopathological features and clinical outcome. 40 formalin-fixed paraffin-embedded (FFPE) lymph node samples obtained from CLL/SLL patients were classified into two categories, “PCs rich” and “typical.” We found a significant common expression level of 4 miRNAs; however, we did not find any significant relationship between PCs presence and miRNAs expression. Moreover, neither the presence of 13q deletion nor the percentage of cells carrying the deletion strictly correlated with miRNAs expression levels, although a significant number of patients with 13q deletion presented hsa-miR-16-1-3p levels below the median value in normal samples (P < 0.05). Finally, although no correlation was found between the expression of each miRNA and other clinicopathological features (Ki67, CD38, ZAP70, and IGVH@ hypermutations), the OS curves showed a positive trend in patients with miRNAs downregulation, though not statistically significant. In conclusion, we showed for the first time that all miRNAs can be successfully studied in FFPE CLL tissues and that del13q and PCs richness do not strictly correspond to miRNAs downregulation; therefore, a specific evaluation may be envisaged at least in patients enrolled in clinical trials.

Proliferation centers in chronic lymphocytic leukemia: correlation with cytogenetic and clinicobiological features in consecutive patients analyzed on tissue microarrays

To better define the significance of proliferation centers (PCs), the morphological hallmark of chronic lymphocytic leukemia (CLL), lymph node biopsies taken from 183 patients were submitted to histopathologic and fluorescence in situ hybridization (FISH) studies using a 5-probe panel on tissue microarrays. Seventy-five cases (40.9%) with confluent PCs were classified as 'PCs-rich' and 108 cases (59.1%) with scattered PCs were classified as 'typical'. Complete FISH data were obtained in 101 cases (55.1%), 79 of which (78.2%) displayed at least one chromosomal aberration. The incidence of each aberration was: 13q- 36,7%, 14q32 translocations 30.8%, 11q- 24.7%, trisomy 12 19.5% and 17p- 15.6%. Five cases showed extra copies of the 14q32 region. The 'PCs-rich' group was associated with 17p-, 14q32/IgH translocation, +12, Ki-67>30%. The median survival from the time of tissue biopsy for PCs-rich and typical groups was 11 and 64 months, respectively (P=0.00001). The PCs-rich pattern was the only predictive factor of an inferior survival at multivariate analysis (P=0.022). These findings establish an association between cytogenetic profile and the amount of PC in CLL, and show that this histopathologic characteristic is of value for risk assessment in patients with clinically significant adenopathy.

Reassessment of small lymphocytic lymphoma in the era of monoclonal B-cell lymphocytosis

BACKGROUND

In the 2008 World Health Organization classification, small lymphocytic lymphoma is defined as a neoplasm with the tissue morphology and immunophenotype of chronic lymphocytic leukemia, but with absence of leukemia. Minimal criteria of tissue involvement to separate small lymphocytic lymphoma from monoclonal B-cell lymphocytosis have not been defined.

DESIGN AND METHODS

We reviewed the clinicopathological features of 36 patients with extramedullary tissue biopsies containing chronic lymphocytic leukemia-type cells and less than 5×10(9)/L peripheral blood monoclonal B cells. Pathological features (extent and patterns of involvement, architectural preservation, presence of proliferation centers) as well as cytogenetic and radiological findings were examined in relation to clinical outcome.

RESULTS

The biopsies were performed to evaluate lymphadenopathy in 20 patients and for other reasons (most frequently staging of a non-hematologic neoplasm) in 16 patients. At latest follow-up (median 23 months), 21 untreated patients had no or stable lymphadenopathy, 3 had regressed lymphadenopathy, and 12 had developed progressive lymphadenopathy and/or received therapy for chronic lymphocytic leukemia/small lymphocytic lymphoma. Features associated with progression/treatment included lymph nodes 1.5 cm or greater on imaging studies (P=0.01) and presence of proliferation centers in the biopsied tissue (P=0.004). Neither the size nor extent of involvement of the excised lymph node correlated with progression/treatment.

CONCLUSIONS

Our findings suggest that biopsies containing chronic lymphocytic leukemia-type cells, but lacking proliferation centers and with non-enlarged or only slightly enlarged lymph nodes on imaging, represent a very indolent disease that may best be considered a tissue equivalent of monoclonal B-cell lymphocytosis rather than overt small lymphocytic lymphoma. We propose that such cases be designated as tissue involvement by chronic lymphocytic leukemia/small lymphocytic lymphoma-like cells of uncertain significance.

Chronic Lymphocytic Leukemia, Small Lymphocytic Lymphoma, and Monoclonal B-Cell Lymphocytosis

Chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), and monoclonal B-cell lymphocytosis (MBL) are clonal proliferations of small, mature B cells. CLL and SLL are considered neoplastic, although they are indolent and many patients with these lymphomas never require treatment. Most MBL cases share immunophenotypic and genetic features with CLL and SLL but have a small burden of clonal cells. This review focuses on the pathologic features of CLL, SLL, and MBL and their differential diagnoses. Guidelines are provided to separate the entities from one another and to avoid pitfalls in distinguishing these entities from other lymphomas and from reactive lymphoid proliferations.

Most morphologic features in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) do not reliably predict underlying FISH genetics or immunoglobulin heavy chain variable region somatic mutational status

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is common in the Western world. Genetic abnormalities detected by fluorescence in situ hybridization (FISH) and immunoglobulin heavy chain variable gene region (IGHV) mutational status are well-known independent prognostic indicators in CLL/SLL. Given the requirement for specialized testing to detect such aberrations, we investigated whether morphologic features may predict the presence of a more or less favorable genetic profile. Forty-one SLL cases were morphologically evaluated for expanded proliferation centers, increased large cells outside of proliferation centers, and nuclear contour irregularities (NCI) in small and large tumor cells. ZAP-70 immunohistochemistry and FISH (deletions of 13q14, p53 and ATM and trisomy 12) were successful in all cases. IGHV mutational status was determined in 26/41 cases. Significant NCI in both small and large cells correlated with the presence of an unfavorable FISH abnormality (ie, ATM or p53 deletions). However, despite good specificity (94%), the sensitivity (57%) of this finding is inadequate for routine use. No other significant associations with morphologic features were identified. Strong ZAP-70 positivity correlated with unmutated IGHV (P=0.001), rendering ZAP-70 IHC a useful surrogate for IGHV mutational status. ZAP-70 positivity predicted against finding a favorable FISH deletion 13q14 (P=0.023). Although we only studied 41 cases, we corroborated their validity using Kaplan-Meier overall survival analysis. In conclusion, morphologic features in SLL are not a reliable predictor of underlying genetic status. Thus, we propose a practical, cost-effective approach to the work-up of these cases, which should be driven by clinical necessity.

Expanded and highly active proliferation centers identify a histological subtype of chronic lymphocytic leukemia ("accelerated" chronic lymphocytic leukemia) with aggressive clinical behavior

BACKGROUND

The concept of "accelerated" chronic lymphocytic leukemia is frequently used by both pathologists and clinicians. However, neither histological criteria to define this form of chronic lymphocytic leukemia nor its clinical correlates and prognostic impact have been formally defined in large series of patients.

DESIGN AND METHODS

Tissue biopsies from 100 patients with chronic lymphocytic leukemia were analyzed for the size of proliferation centers and their proliferation rate as assessed by mitosis count and Ki-67 immunostaining. Histological patterns were correlated with main clinico-biological features and outcome.

RESULTS

A suspicion of disease transformation was the main reason for carrying out tissue biopsy, which was performed at a median time of 14 months (range, 0 to 204 months) after the diagnosis of chronic lymphocytic leukemia. The biopsy showed histological transformation to diffuse large B-cell lymphoma in 22 cases. In the remaining 78 patients, the presence of expanded proliferation centers (broader than a 20x field) and high proliferation rate (either >2.4 mitoses/proliferation center or Ki-67 >40%/proliferation center) predicted a poor outcome and were selected to define a highly proliferative group. Thus, 23 patients with either expanded proliferation centers or high proliferation rate were considered as having "accelerated" chronic lymphocytic leukemia. These patients displayed particular features, including higher serum lactate dehydrogenase levels and more frequently elevated ZAP-70 than "non-accelerated" cases. The median survival from biopsy of patients with "non-accelerated" chronic lymphocytic leukemia, "accelerated" chronic lymphocytic leukemia and transformation to diffuse large B-cell leukemia was 76, 34, and 4.3 months, respectively (P<0.001).

CONCLUSIONS

The presence of expanded and/or highly active proliferation centers identifies a group of patients with "accelerated" chronic lymphocytic leukemia characterized by an aggressive clinical behavior.

Intravascular lymphocytosis in acute appendicitis: potential mimicry of chronic lymphocytic leukaemia

AIMS

Intravascular lymphocytosis (IVL) in appendectomy specimens is a fairly common phenomenon but has not been described and studied in detail. The aim was to describe the IVL phenomenon in appendiceal specimens removed for appendicitis that can mimic chronic lymphocytic leukaemia and to investigate factors that could contribute to the development of IVL.

METHODS AND RESULTS

The clinicopathology of 100 appendectomy cases and the appendices from 20 right hemicolectomy cases were reviewed. The IVL phenomenon was more commonly seen in laparoscopic appendectomy specimens [Fisher's exact 0.011, odds ratio (OR) 3.14] and in patients <38 years old (Fisher's exact 0.012, OR 3.01).

CONCLUSIONS

Surgical manipulation and the patient's innate immunity are contributary factors to the development of the IVL phenomenon. Pathologists should be aware of this histological artefact in order to prevent overdiagnosis of intravascular lymphoid neoplasia.

CD38 expression in chronic lymphocytic leukemia is regulated by the tumor microenvironment

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease with a highly variable outcome. The prognosis of patients with CLL may be predicted using a number of biomarkers, including the level of CD38 expression at the leukemic cell surface. This study investigates the hypothesis that CD38 expression by CLL cells reflects interactions with nonmalignant cells within pseudofollicles in secondary lymphoid tissue where tumor cell proliferation is thought to occur. CD38 expression is higher in tissues that contain pseudofollicles compared with those that do not. In addition, we show that CD38 expression in CLL is dynamic, changes in response to contact with activated CD4(+) T cells, and identifies cells that are primed to proliferate. Finally, we demonstrate close contact between activated CD4(+) T cells and proliferating tumor in primary patient tissue. Proliferating tumor cells in lymph nodes express CD38, which is in turn associated with an increased number of CD31(+) vascular endothelial cells. Although the factors resulting in colocalization of tumor, T cells, and endothelium remain unclear, the existence of these cellular clusters may provide an explanation for the association between CD38 expression and adverse outcome in CLL and suggests novel therapeutic targets.

Application of Immunohistochemistry in the Diagnosis of Non-Hodgkin and Hodgkin Lymphoma

Context.—Beginning with the immunologic classifications of Lukes and Collins and Kiel and culminating in the Revised European-American Lymphoma and World Health Organization classifications, the diagnosis of lymphoid tumors relies heavily on the determination of cell lineage, maturation, and function, based on antigen expression in addition to morphology and clinical features. Technologic advances in immunology, antibody production, genetic analysis, cloning, and the identification of new genes and proteins by microarray and proteomics have provided pathologists with many antibodies to use in routine diagnosis.

Objective.—To provide guidance to the practicing pathologist in the appropriate selection of an antibody panel for the diagnosis of lymphoma based on morphology and relevant clinical data and to avoid pitfalls in the interpretation of immunohistochemical data. Attention is given to some of the newer antibodies, particularly against transcription factors, that are diagnostically and prognostically useful.

Data Sources.—The information presented in this article is based on review of the literature using the OVID database (Ovid MEDLINE 1950 to present with daily update) and 20 years of experience in diagnostic hematopathology.

Conclusions.—Immunophenotyping is required for the diagnosis and classification of lymphoid malignancies. Many paraffin-reactive antibodies are available to the pathologist but most are not specific. To avoid diagnostic pitfalls, interpretation of marker studies must be based on a panel and knowledge of a particular antigen's expression in normal, reactive, and neoplastic conditions.

The proliferation center microenvironment and prognostic markers in chronic lymphocytic leukemia/small lymphocytic lymphoma

Prognostication in chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) based, in part, on ZAP-70 and CD38 expression, and to a lesser extent, on MUM1/IRF4 expression, is currently of great interest. The more aggressive type of CLL/SLL is reportedly characterized by neoplastic cells that are more responsive to B-cell signaling with proliferation centers (PCs), a potentially important site of neoplastic cell stimulation. To study the relationship of these markers to each other and to the pattern of PCs, immunohistochemical stains for ZAP-70 and MUM1/IRF4 were performed and the PC patterns assessed (where possible) in 29 tissue biopsies with CLL/SLL. CD38 expression was assessed in 18 cases using flow cytometry. Ten evaluable cases had a typical PC pattern and 16 an atypical pattern with larger or more confluent PCs and/or more numerous paraimmunoblasts/transformed cells. ZAP-70 was positive in 14 of 28 cases, including 3 with atypical PCs and enhanced PC staining. All 29 cases showed MUM1/IRF4 expression in PCs. Seven cases, none with atypical PC, also showed uniform positivity throughout, 14 showed weaker staining of surrounding lymphocytes, and 8 had PC staining only. CD38 was positive in 14 of 18 cases. The only significant association identified was between uniform MUM1/IRF4 positivity and typical PCs (P = .004). These findings highlight the complex interrelationship of prognostic markers in CLL/SLL and demonstrate potentially important microenvironmental variations in their expression. They support the hypothesis that PCs are a site for B-cell receptor signaling, which helps explain reported site-dependent antigenic variation in CLL/SLL, and suggest that PC morphology may correlate with other biological features.

CD5-Positive B-Cell Neoplasms of Indeterminate Immunophenotype

The flow cytometric classification of CD5-positive small B-cell neoplasms is dependent largely on the differential expression of CD23 and FMC-7. Occasional CD5-positive neoplasms with prominent co-expression of these antigens are encountered, precluding definitive immunophenotypic classification. The authors studied the clinicopathologic features of 26 neoplasms with this indeterminate immunophenotype. Available morphologic material was reviewed and analysis of CYCLIN D1 derangement was performed in selected cases by a combination of immunohistochemical, molecular, and cytogenetic techniques. Individual neoplasms were classified based on correlation of morphologic features and results of CYCLIN D1 studies. The neoplasms were classified into five categories: chronic lymphocytic leukemia (14 cases), "favor chronic lymphocytic leukemia" (3 cases), mantle cell lymphoma (3 cases), lymphoplasmacytic lymphoma (1 case), and unclassifiable (5 cases). Three of the unclassifiable neoplasms had morphologic features of mantle cell lymphoma, but CYCLIN D1 derangement could not be demonstrated. Neither relative expression of CD23 and FMC-7 nor intensity of CD20 or surface immunoglobulin expression was helpful in final classification. The authors conclude that CD5-positive small B-cell neoplasms with an indeterminate immunophenotype are a heterogeneous group, requiring additional studies for final classification. The majority (65%) appear to be chronic lymphocytic leukemia, with most of the remaining cases either definitively mantle cell lymphoma or unclassifiable.

Surface and cytoplasmic immunoglobulin expression in B-cell chronic lymphocytic leukemia (CLL)

Flow cytometric analysis of abnormal lymphocyte populations in chronic lymphocytic leukemia (CLL) has been widely reported to show weak expression of surface immunoglobulin (sIg). The international scoring system to help discriminate between CLL and other B-cell lymphoproliferative disorders lists this as the first of 5 criteria worth 1 point each. In the present study, 30 cases of CLL were studied for surface and cytoplasmic Ig expression. 23 of these 30 (76.7%) cases were positive for sIg. Of these 23, 14 cases (60.9%) showed moderate to bright sIg expression. All of these 23 cases were positive for CD5 and CD23; all were negative for CD10 and only 6 (26.1%) were positive for FMC7. 27 of 30 (90.0%) cases expressed cytoplasmic immunoglobulin (cIg) compared to 5% reported by others. This shows that cytoplasmic Ig occurs in a much greater percentage of cases than reported previously. 23 of 30 (76.7%) cases showed positivity for both surface and cytoplasmic Ig, with 15 showing kappa light chain restriction and 8 showing lambda light chain restriction. Six expressed cytoplasmic Ig only, with 4 showing kappa light chain restriction and 2 showing lambda light chain restriction. One case expressed neither cytoplasmic nor surface Ig. CD38 positivity portends a worse prognosis. Of the 29 cases tested for CD38, 13 (44.8%) were positive. Of these 13 cases, 12 were in the surface Ig/cytoplasmic Ig+ group and 1 in the cytoplasmic Ig+ group only. Also, of the 23 cases tested for CD22 expression, 16 (69.6%) were positive. These data question the use of both "weak" surface Ig expression and lack of CD22 expression as valid scoring criteria for CLL.

Real-time quantitative reverse transcription-PCR for cyclin D1 mRNA in blood, marrow, and tissue specimens for diagnosis of mantle cell lymphoma

BACKGROUND

Overexpression of cyclin D1 mRNA, found in mantle cell lymphoma (MCL), is a critical diagnostic marker. We investigated the use of real-time reverse transcription-PCR (RT-PCR) for cyclin D1.

METHODS

We studied 97 fresh specimens (50 blood, 30 bone marrow, 15 lymph node, and 2 other samples) from patients diagnosed with a variety of lymphoproliferative diseases, including 25 cases of MCL. We used real-time quantitative RT-PCR to evaluate cyclin D1 mRNA expression. Because blood and marrow specimens may contain only a minority of potentially malignant cells (as opposed to most lymph nodes) and to increase sensitivity, we normalized the cyclin D1 mRNA concentrations to mRNA of a B-cell-specific marker, CD19, as well as to previously characterized beta(2)-microglobulin mRNA.

RESULTS

In 16 of 21 cases of MCL with overt disease, the ratio of cyclin D1 mRNA to beta(2)-microglobulin mRNA was increased, but all 21 cases showed increased ratios of cyclin D1 mRNA to CD19 mRNA. Cyclin D1 mRNA was low or undetectable in various lymphoproliferative diseases, including cases of ambiguous immunophenotype. The mRNA ratios were stable over 3-7 days of sample storage.

CONCLUSION

Quantitative RT-PCR for cyclin D1 mRNA normalized to CD19 mRNA can be used in the diagnosis of MCL in blood, marrow, and tissue.

Immunobiology of chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia increasingly is being recognized as a useful model disease with which to study more general processes involved in the evolution of neoplastic disease. The accessibility of the tumor cells and the capacity to confirm their clonal relatedness allow for evaluation of the processes associated with neoplastic transformation and/or disease progression. Recent studies have provided fascinating insight into the potential pathogenesis and pathophysiology of this disease. In addition, features of leukemia cells have been identified that can distinguish subsets of patients that have different tendencies for disease progression. Gene expression studies have identified a relatively small number of genes that are differentially expressed between these subsets, allowing for focused attention on proteins that might contribute to the noted differences in clinical behavior. Finally, recognition that chronic lymphocytic leukemia cells depend upon specific microenvironmental growth and survival factors identifies novel targets for disease intervention. This article focuses on the reports of the past year that have contributed to these areas of active research on chronic lymphocytic leukemia, the most common adult leukemia in Western societies.