How reliable is histologic examination of bone marrow trephine biopsy specimens for the staging of non-Hodgkin lymphoma? A study of hairy cell leukemia and mantle cell lymphoma involvement of the bone marrow trephine specimen by histologic, immunohistochemical, and polymerase chain reaction techniques

Bone marrow aspiration and biopsy: techniques and practice implications

Bone marrow aspiration and biopsy (BMAB) is a valuable diagnostic procedure commonly performed for evaluation of a wide spectrum of diseases including hematologic abnormalities, nonhematologic malignancies, metabolic abnormalities, and tumor treatment response such as chemotherapy and bone marrow transplantation, hematologic tumor staging, and suspected infection in patients with fever of unknown origin. This minimally invasive intervention offers excellent safety profile and a high diagnostic yield. Radiologists should be familiar with clinical implications of BMAB for patient care and be able to implement various technical armamentarium available to achieve a safe intervention while maximizing procedure yield.

Bone Marrow Involvement by Aggressive B Cell Lymphoma Undetected by Aspirate Immunophenotyping

Staging for newly diagnosed lymphoma is an essential diagnostic step aimed at not only estimating prognosis but also refining the ensuing therapeutic pathway. Bone marrow is routinely sampled for this reason. Morphological assessment of the bone marrow aspirate and biopsy remains the gold standard approach. Nonetheless, ancillary testing such as aspirate immunophenotyping is also used with the aim to increase sensitivity and add diagnostic utility, e.g., to provide proof of clonality. Both of these techniques are fraught with shortcomings and concordance is often not perfect. Cases of infiltrative lymphoma identified by morphology, and not detected by flow cytometry highlights the dangers of over reliance on aspirate immunophenotyping. Under sampling, disintegration, fibrosis and hemodilution are but some causes of a false negative flow result. Therefore, neither technique is sufficient in isolation. In this submission, a case of such a discrepancy is presented as an introduction for review of literature that highlights this phenomenon.

Bone marrow infiltration by flow cytometry at diffuse large B-cell lymphoma NOS diagnosis implies worse prognosis without considering bone marrow histology

BACKGROUND

The significance of discrepant findings between histology (BMB) and flow cytometry (FC) in bone marrow (BM) examination at diffuse large B-cell lymphoma (DLBCL) diagnosis is uncertain.

METHODS

We performed a 5-year retrospective single-center study of patients diagnosed by DLBCL not otherwise specified (n = 82), divided into three groups according to BM infiltration at diagnosis: BMB-/FC- (75.6%), BMB+/FC+ (13.4%), and BMB-/FC+ (11%).

RESULTS

Median infiltration by FC analysis of the BMB-/FC+ group was 0.8% and if we considered BM infiltration as positive in all cases, 4/9 would be upstaged. Median follow was 33 months. Event-free survival (EFS) after 18 months was 82, 23, and 27% for BMB-/FC-, BMB-/FC+, and BMB+/FC+, respectively (p < .001). After 18 months of observation, OS was 87, 46, and 55% for BMB-/FC-, BMB-/FC+, and BMB+/FC+, respectively (p = .001). In multivariate analysis (BM infiltration vs. cell-of-origin according to Hans algorithm and standard IPI), BM infiltration was independently associated with EFS (HR: 1.94, 95% CI: 1.3-2.9) and overall survival (HR: 1.69, 95% CI: 1.1-2.7).

CONCLUSION

In summary, minimal BM infiltration, detected by FC but not by BMB, has same prognostic implications than overt BM infiltration and should be considered as extranodal involvement regardless the infiltration quantity.

Trends in Bone Marrow Sampling and Core Biopsy Specimen Adequacy in the United States and Canada: A Multicenter Study

OBJECTIVES

To assess bone marrow (BM) sampling in academic medical centers.

METHODS

Data from 6,374 BM samples obtained in 32 centers in 2001 and 2011, including core length (CL), were analyzed.

RESULTS

BM included a biopsy (BMB; 93%) specimen, aspirate (BMA; 92%) specimen, or both (83%). The median (SD) CL was 12 (8.5) mm, and evaluable marrow was 9 (7.6) mm. Tissue contraction due to processing was 15%. BMB specimens were longer in adults younger than 60 years, men, and bilateral, staging, and baseline samples. Only 4% of BMB and 2% of BMB/BMA samples were deemed inadequate for diagnosis. BM for plasma cell dyscrasias, nonphysician operators, and ancillary studies usage increased, while bilateral sampling decreased over the decade. BM-related quality assurance programs are infrequent.

CONCLUSIONS

CL is shorter than recommended and varies with patient age and sex, clinical circumstances, and center experience. While pathologists render diagnoses on most cases irrespective of CL, BMB yield improvement is desirable.

[Bone marrow biopsy: processing and use of molecular techniques]

The rapid technological development in diagnostic pathology, especially of immunohistochemical and molecular techniques, also has a significant impact on diagnostic procedures for the evaluation of bone marrow trephine biopsies. The necessity for optimal morphology, combined with preservation of tissue antigens and nucleic acids on one hand and the wish for short turnaround times on the other hand require careful planning of the workflow for fixation, decalcification and embedding of trephines. Although any kind of bone marrow processing has its advantages and disadvantages, formalin fixation followed by EDTA decalcification can be considered a good compromise, which does not restrict the use of molecular techniques. Although the majority of molecular studies in haematological neoplasms are routinely performed on bone marrow aspirates or peripheral blood cells, there are certain indications, in which molecular studies such as clonality determination or detection of specific mutations need to be performed on the trephine biopsy. Especially, the determination of B- or T-cell clonality for the diagnosis of lymphoid malignancies requires stringent quality controls and knowledge of technical pitfalls. In this review, we discuss technical aspects of bone marrow biopsy processing and the application of diagnostic molecular techniques.

Usefulness of flow cytometric immunophenotyping for bone marrow staging in patients with mantle cell lymphoma after therapy

We evaluated the role of flow cytometric immunophenotyping (FCI) in the assessment of bone marrow (BM) specimens in 104 patients with mantle cell lymphoma (MCL) following treatment with aggressive combination chemotherapy. Of the patients, 77 had no morphologic or FCI evidence of MCL, 13 had morphologic and FCI evidence of MCL, and 14 patients were morphologically negative but FCI showed CD5+ clonal B-cells (M-/FCI+). Retrospective cyclin D1 immunostaining was positive in 3 of 12 M-/FCI+ cases. Clinical staging and follow-up showed that 4 of 12 patients had concurrent extramedullary involvement by MCL, 5 patients subsequently became M+ for MCL in BM (within 2-24 months), and 3 patients had no recurrent MCL on follow-up. We conclude that FCI is more sensitive than morphologic examination of BM at the time of restaging in patients with MCL and that positivity by only FCI in BM often correlates with concurrent disease or subsequent relapse.

Routine use of ancillary investigations in staging diffuse large B-cell lymphoma improves the International Prognostic Index (IPI)

BACKGROUND

The International Prognostic Index (IPI) is used to determine prognosis in diffuse large B-cell lymphoma (DLBCL). One of the determinants of IPI is the stage of disease with bone marrow involvement being classified as stage IV. For the IPI, involvement on bone marrow is traditionally defined on the basis of histology with ancillary investigations used only in difficult cases to aid histological diagnosis. This study aimed to determine the effect of the routine use of flow cytometry, immunohistochemistry and molecular studies in bone marrow staging upon the IPI.

RESULTS

Bone marrow trephines of 156 histologically proven DLBCL cases at initial diagnosis were assessed on routine histology, and immunohistochemistry using two T-cell markers (CD45RO and CD3), two B-cell markers (CD20 and CD79a) and kappa and lambda light chains. Raw flow cytometry data on all samples were reanalysed and reinterpreted blindly. DNA extracted from archived paraffin-embedded trephine biopsy samples was used for immunoglobulin heavy chain and light chain gene rearrangement analysis. Using immunophenotyping (flow cytometry and immunohistochemistry), 30 (19.2%) cases were upstaged to stage IV. A further 8 (5.1%) cases were upstaged using molecular studies. A change in IPI was noted in 18 cases (11.5%) on immunophenotyping alone, and 22 (14.1%) cases on immunophenotyping and molecular testing. Comparison of two revised IPI models, 1) using immunophenotyping alone, and 2) using immunophenotyping with molecular studies, was performed with baseline IPI using a Cox regression model. It showed that the revised IPI model using immunophenotyping provides the best differentiation between the IPI categories.

CONCLUSION

Improved bone marrow staging using flow cytometry and immunohistochemistry improves the predictive value of the IPI in patients with DLBCL and should be performed routinely in all cases.

Staging bone marrow in diffuse large B-cell lymphoma: the role of ancillary investigations

Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin's lymphoma (NHL) that requires treatment at initial diagnosis. Treatment decisions may be guided by staging investigations, which include assessment of bone marrow (BM). Traditionally this assessment has included light microscopic examination of the bone marrow aspirate and trephine biopsy. Ancillary testing--including immunophenotyping using flow cytometry on BM aspirates, immunohistochemistry (IHC) on BM trephines and molecular studies using immunoglobulin heavy (IgH) or light (IgL) chain gene rearrangements--are performed as required to aid histological diagnosis. This review examines the evidence for the routine use of ancillary tests in the initial staging of DLBCL, including the limitations, potential pitfalls and possible clinical implications of their use in this setting.

Clinical role of flow cytometry in redefining bone marrow involvement in diffuse large B-cell lymphoma (DLBCL) - a new perspective

AIMS

The clinical role of flow cytometry in staging bone marrow in diffuse large B-cell lymphoma (DLBCL), especially its impact on outcome, remains uncertain. The aim was to determine the contribution of flow cytometry to conventional staging, and to study the impact of this revised staging on survival.

METHODS AND RESULTS

One hundred and thirteen cases of DLBCL diagnosed at The Canberra Hospital from 1996 to 2005 were identified. Blinded analysis of bone marrow (BM) morphology and flow cytometric data showed involvement on morphology (M) in 25 (22.1%) cases, on flow cytometry (F) in 21 (18.6%) cases and overall (M + F) in 32 cases (28.3%); discordance was noted in 16 cases (16.1%). Cases with and without marrow involvement on conventional staging alone (M) had no significant difference in survival (P = NS). However, when BM involvement was defined as positivity on morphology and/or flow cytometry (M + F), the median survival of patients with involvement was significantly worse than patients without involvement (P = 0.026).

CONCLUSIONS

Flow cytometry-positive cases should be included with those positive on morphology in a summative model to define BM involvement in DLBCL, as it may have a potential impact on predicting outcome.

Diagnosis and Classification of Malignant Lymphoma and Related Entities in the Bone Marrow Trephine Biopsy

The trephine bone marrow (BM) biopsy is an important diagnostic tool in patients with malignant lymphoma. BM examination can serve to establish or confirm a primary diagnosis of lymphoma or to determine the extent of disease dissemination for staging purposes. BM histology renders information which cannot be gained equally from aspirate material, such as spacial distribution and extent of infiltrates, BM cellularity and fibrosis. Furthermore, cytology including flow cytometric immunophenotyping can give false-negative results in BM involvement by lymphoma due to intralesional fibrosis. In addition to morphological examination, the availability of a broad panel of antibodies suitable for paraffin-embedded tissues, in conjunction with less damaging decalcification procedures, nowadays enables us to perform complete immunophenotyping on BM trephines and allows for classification of lymphoma infiltrates according to established algorithms. Molecular determination of clonality and interphase fluorescent in situ hybridization can be employed selectively to resolve difficult cases. This review describes important diagnostic features of malignant lymphoma in the BM, relevant differential diagnoses, and the proper use of ancillary techniques.

Ancillary techniques in bone marrow pathology: molecular diagnostics on bone marrow trephine biopsies

Pathologic examination of trephine bone marrow (BM) biopsies plays a central role in the diagnosis and staging of haematological neoplasms and other disorders affecting haematopoiesis. Haematopathology has been profoundly influenced by the advent of molecular genetic techniques suitable for paraffin-embedded tissues, and certain applications, such as the determination of B- and T-cell clonality, belong to its standard diagnostic repertoire. Many of these molecular tests can be performed successfully with nucleic acids extracted from BM trephine biopsies, if some technical aspects specific to this template source such as various fixation and decalcification procedures are taken into consideration. The current indications for molecular BM diagnostics range from the confirmation of lymphoma involvement with gene rearrangement analysis, demonstration of tumor-specific translocations in lymphoid and chronic myeloproliferative disorders along to the detection of microorganisms or marrow involvement by soft tissue sarcomas. The availability of quantitative polymerase chain reaction techniques for the investigation of allelic imbalances and gene expression levels in paraffin-embedded material also open new avenues for research and advanced diagnostics. The molecular detection of minimal residual disease in haematological neoplasms, especially in the context of new treatment strategies, will provide future challenges. This article summarizes the current state of the art in molecular diagnostics applied to paraffin-embedded BM biopsies.

A pathologist's perspective on bone marrow aspiration and biopsy: I. Performing a bone marrow examination

The bone marrow aspirate and biopsy is an important medical procedure for the diagnosis of hematologic malignancies and other diseases, and for the follow-up evaluation of patients undergoing chemotherapy, bone marrow transplantation, and other forms of medical therapy. During the procedure, liquid bone marrow is aspirated from the posterior iliac crest or sternum with a special needle, smeared on glass microscope slides by one of several techniques, and stained by the Wright-Giemsa or other techniques for micro-scopic examination. The bone marrow core biopsy is obtained from the posterior iliac crest with a Jamshidi or similar needle and processed in the same manner as other surgical specimens. Flow cytometric examination, cytochemical stains, cytogenetic and molecular analysis, and other diagnostic procedures can be performed on bone marrow aspirate material, while sections prepared from the bone marrow biopsy can be stained by the immunoperoxidase or other techniques. The bone marrow procedure can be performed with a minimum of discomfort to the patient if adequate local anesthesia is utilized. Pain, bleeding, and infection are rare complications of the bone marrow procedure performed at the posterior iliac crest, while death from cardiac tamponade has rarely occurred from the sternal bone marrow aspiration. The recent development of bone marrow biopsy needles with specially sharpened cutting edges and core-securing devices has reduced the discomfort of the procedure and improved the quality of the specimens obtained.

Clinical utility of bone marrow flow cytometry in B-cell non-Hodgkin lymphomas (B-NHL)

AIM

To determine the efficacy of flow cytometry (FC) in the assessment of bone marrow (BM) in B-cell non-Hodgkin lymphoma (B-NHL). FC is a common practice, but is far from being validated.

METHODS AND RESULTS

Morphological analysis and FC immunophenotyping were performed on 421 samples. T-cell lymphomas, Hodgkin's disease, chronic lymphocytic leukaemia and hairy cell leukaemia were not included in the study. Clonality was assessed by the standard kappa/lambda/CD19 test. Aberrant immunophenotypes present in the B-cell subpopulation were also investigated. A double-step procedure was employed in all cases to increase the sensitivity of the FC procedure. Of 380 evaluable samples, 188 corresponded to follicular lymphoma (FL), 58 to diffuse large B-cell lymphoma (DLBCL), 57 to mantle cell lymphoma (MCL), seven to Burkitt's lymphoma and the remaining 70 samples to other low-grade lymphomas. Morphological marrow infiltration was found in 148 cases, and flow immunophenotyping identified 138 cases with BM involvement. A concordance between the two methods was detected in 298 cases (79%). There was a discordance in 82 cases (21%): morphology positive/FC negative in 46 cases and morphology negative/FC positive in 36 (61% of all cases with discordance were from FL). There was no difference in outcome when patients with discordances were compared with patients without discordances.

CONCLUSIONS

Most samples showed concordance between morphological and FC results. FC identified BM involvement in the absence of morphological infiltration. Morphology/FC discordance seems to have no influence on the outcome of FL patients.

Hodgkin and non-Hodgkin lymphoma involving bone marrow

The role of bone marrow examination in diagnosis and staging of patients with Hodgkin lymphoma, B-non-Hodgkin lymphoma, and T-non-Hodgkin lymphoma is reviewed. Optimal routine and specialized bone marrow examination techniques are discussed. The salient morphologic, immunophenotypic, and genetic features of mature and immature B, T neoplasms and classic Hodgkin lymphoma in bone marrow are delineated, along with recommendations to distinguish these overt neoplasms from non-neoplastic processes.

Update in the pathologic features of mature B-cell and T/NK-cell leukemias

Modern diagnosis of mature B- and T-cell leukemias requires integration of morphologic, immunophenotypic, and molecular genetic features. This integrative approach has allowed more precise definitions of specific disease entities. This in turn provides better information for clinicians to select proper therapy and determine prognosis. The characteristic pathologic features of these disorders are reviewed.

A comparison of flow cytometry, bone marrow biopsy, and bone marrow aspirates in the detection of lymphoid infiltration in B cell disorders

AIMS

To evaluate the diagnostic value of bone marrow aspirates, trephine biopsies (BMB), and flow cytometry (FC) in the assessment of bone marrow infiltration in chronic lymphoid disorders.

METHODS

Investigations were carried out in 110 diagnostic and follow up specimens from B cell disorders, namely: chronic lymphocytic leukaemia (CLL; 65), non-Hodgkin's lymphoma (NHL; 39), and hairy cell leukaemia (HCL; 6). A selected panel of monoclonal antibodies was used both for FC and immunohistochemistry.

RESULTS

In CLL there was agreement between the three investigations in 71% of samples and in 88% when only FC and BMB were compared. In nine of 65 samples, FC and BMB were positive, although the aspirate was reported as negative. Four BMB negative samples had minimal residual disease (MRD) detected by FC, whereas two samples were positive both on BMB and aspirate but showed no evidence of disease on FC. In NHL, there was agreement between the three investigations in 22 of 39 cases, and in 27 of 39 cases there was agreement between FC and BMB. In eight of 39 NHL cases, FC was negative but the BMB was either positive (five) or uncertain (three), whereas in three of 39, FC was positive but BMB was either negative (one) or uncertain (two). In three of five uncertain BMB, no clonal population was detected by the polymerase chain reaction, whereas in the remaining two cases the nodular aggregates disappeared on further sectioning.

CONCLUSIONS

Both BMB and FC are better than bone marrow aspirates for the detection of infiltration in B cell disorders. FC might be slightly more sensitive than BMB to detect MRD in CLL, whereas BMB may be slightly better than FC in NHL.

Bone marrow biopsy: interpretive guidelines for the surgical pathologist

Ideally, the bone marrow core biopsy should be reviewed with knowledge of the clinical history, complete blood count, and findings in the peripheral blood and bone marrow aspirate smears. However, for a variety of reasons, the pathologist may receive the core biopsy and aspirate clot section without all of this information. Although this approach is not optimal, a great deal of valuable information can be generated from these specimens. Over the past 20 years, there has been considerable progress in the fields of flow cytometric analysis, immunohistochemistry, and molecular diagnostic studies that can be performed on smears or extracted DNA from paraffin embedded tissue. These modalities have augmented and refined diagnostic criteria formerly ascertained by light microscopy, cytochemistry, and cytogenetics. This is particularly true of some myeloid and lymphoreticular neoplasms where a collaborative and multidisciplinary approach to the diagnosis has become necessary. Despite this growing complexity and dependence on newer methodologies, the traditional role of histopathology in evaluating the bone marrow biopsy remains as important as it has been in the past. In this review, we focus on contemporary practices and expectations for interpreting bone marrow biopsies and clot sections.

Analysis of immunoglobulin H gene rearrangement by polymerase chain reaction in primary central nervous system lymphoma

OBJECT

Diagnosing primary central nervous system lymphoma (PCNSL) may be difficult either because of a paucity of tumor cells in the brain biopsy specimens or a failure to demonstrate monoclonality on immunomorphological studies. Monoclonality can also be demonstrated by amplification of the rearranged immunoglobulin H genes by polymerase chain reaction (PCR) to the framework region (FR)3 and FR2 complementarity determining region (CDR)-III and CDR-II of these genes. The PCR method is feasible with formalin-fixed, paraffin-embedded biopsy material and has proven to be helpful in the diagnosis of non-Hodgkin lymphoma on biopsy samples obtained from various locations in the body. Nevertheless, few studies have addressed the value of this method in the context of PCNSL. In the present study, the contribution of both FR3 single and FR2 seminested PCR procedures for confirming the diagnosis of PCNSL was estimated retrospectively in 30 cases of PCNSL and in three cases of epidural lymphoma.

METHODS

Twenty-eight cases of immunophenotypically confirmed PCNSL and two of suspected lymphoma were studied. Tissue specimens obtained in 22 cases of other cerebral diseases, among which were various inflammatory conditions. were used as negative controls. In 18 (60%) of 30 cases the results of FR3 PCR demonstrated monoclonality, whereas FR2 PCR showed monoclonality in 12 cases (40%). In 11 cases FR3 PCR yielded monoclonal patterns and FR2 PCR did not, whereas reversibly in five cases FR2 PCR proved monoclonality and FR3 PCR failed to do so. Adding the results of FR3 to those of FR2 PCR, monoclonal patterns were obtained in 23 (77%) of 30 cases. In both cases in which lymphoma was suspected but not proven immunomorphologically, FR3 PCR revealed monoclonality, as did FR2 PCR in one case. In all 22 control lesions either polyclonal patterns were seen or no consistent patterns were obtained. In the PCNSL group, older age of patients and multifocal presentation of lesions on neuroimaging were significantly associated with worse survival. No correlation between histological subtype and clinical outcome was elucidated.

CONCLUSIONS

The application of FR3 and FR2 PCR is a useful additional tool in making the diagnosis of PCNSL. Moreover, in some cases the PCR method may be essential in distinguishing neoplasia from reactive conditions.

Immunohistochemical detection of immunoglobulin light chain expression in B-cell non-Hodgkin lymphomas using formalin-fixed, paraffin-embedded tissues and a heat-induced epitope retrieval technique

Definitive diagnosis of B-cell non-Hodgkin lymphomas often requires demonstration of B-cell monoclonality. Immunohistochemical detection of monotypic immunoglobulin light chain expression, and thereby B-cell monoclonality, may be accomplished readily using fresh cell suspensions or frozen tissue sections. However, immunohistochemical detection of immunoglobulin light chain expression in formalin-fixed, paraffin-embedded tissues is more difficult; with few exceptions, techniques suitable for formalin-fixed, paraffin-embedded tissues are not widely available. This report describes and validates a method for detecting immunoglobulin light chain expression in formalin-fixed, paraffin-embedded tissues using a heat-induced epitope retrieval technique. This method was evaluated in a series of 113 cases of B-cell non-Hodgkin lymphoma, including 73 cases with correlative flow cytometric immunophenotyping data. Monotypic light chain expression was demonstrated in 91 (81%) of 113 cases, including several small core biopsy specimens with extremely limited tissue. Compared with the reference method (flow cytometric immunophenotyping), the specificity of the assay was 100%. Interobserver reproducibility was excellent, with 87% concordance between two independent observers categorizing cases as indeterminate, suggestive or diagnostic of kappa or lambda light chain restriction (Cohen kappa statistic: 0.81). In summary, the described method permits demonstration of immunoglobulin light chain expression in formalin-fixed, paraffin-embedded tissues in approximately 80% of cases of B-cell non-Hodgkin lymphoma with a high degree of specificity and excellent interobserver reproducibility. The assay is sufficiently robust for diagnostic use in small biopsies in which fresh tissue is unavailable.

Reliability of lymphoma classification in bone marrow trephines

The aim of this study was to test and establish the accuracy and reliability of lymphoma classification in bone marrow trephines according to the new World Health Organization (WHO) classification by considering predominantly the morphology and immunophenotype. Therefore, we retrospectively compared lymphoma diagnoses, rendered exclusively on bone marrow trephines without knowledge of lymph node diagnosis in 124 patients, with the results of the reference centres that had reviewed lymph node (n = 90) or extranodal biopsies (n = 34). The overall concordance rate was higher than 85% and 91%, respectively, when patients with discordant malignancy grades were excluded. The concordance rate for low-grade B-cell lymphomas was 93% and for high-grade B-cell lymphomas 84%. The main reasons for discordant diagnoses were divergent immunophenotypes among low-grade B-cell lymphomas (6 out of 81, i.e. 7.4%) and discrepant malignancy grades within high-grade B-cell lymphomas (6 out of 31, i.e. 19.4%). No relationship between discordant diagnoses and chemotherapy given during the course of the disease with the site of biopsy (i.e. lymph nodes, extranodal sites) was noted. We conclude from our results that bone marrow trephines are a reliable tool, not only for establishing bone marrow infiltration, but also for the subtyping of lymphomas.

Polymerase chain reaction-based diagnosis of bone marrow involvement in 170 cases of non-Hodgkin lymphoma

BACKGROUND

Up to the current time, diagnosis of bone marrow (BM) involvement in non-Hodgkin lymphoma (NHL) has been based on morphologic findings. Polymerase chain reaction (PCR) for antigen receptor gene rearrangements has the potential to increase the detection sensitivity of minimal degrees of BM involvement. The authors therefore assessed PCR-based clonalities of BM concurrently with morphology from 170 cases with NHL and evaluated the usefulness of comparative analysis of clonalities between bilateral BMs and the lymph node and the clinical significance of PCR based clonalities of BM.

METHODS

Bilateral BM clot sections of 170 cases and 47 lymph nodes were tested for immunoglobulin heavy chain gene rearrangement or T-cell receptor gamma gene rearrangement according to the B- or T-lineage of the lymph node.

RESULTS

When compared with morphology, the results of PCR showed an unexpectedly low positive concordance rate of 61.0% for B-cell NHL and 57.1% for T-cell NHL. When the clonality of BM was compared with that of lymph nodes in B-cell NHL, bilateral clonalities of BM showed high concordance with the clonality of the lymph nodes. PCR-based clonality did not show significant impact on survival.

CONCLUSIONS

Morphology remains the gold standard in the evaluation of BM involvement by NHL. Although the comparative analysis of BM clonality and that of the lymph nodes is considered a valuable tool that increases the reliability of clonality, PCR-based clonality of BM does not significantly add to the sensitivity of diagnosing BM involvement by NHL.

Evaluation of B cell lymphoid infiltrates in bone marrow biopsies by morphology, immunohistochemistry, and molecular analysis

AIMS

Morphological criteria to distinguish between reactive and neoplastic B cell lymphocytoid infiltrates in trephines have been defined but are not always reliable. Polymerase chain reaction (PCR) analysis of the CDR3 region of the immunoglobulin heavy chain (IgH) gene which, by demonstrating monoclonality, can provide additional arguments in favour of lymphoid malignancy is now frequently used for the detection and follow up of B cell lymphoma (NHL). The aim of this study was to investigate the usefulness of morphological findings in bone marrow biopsies in comparison with data obtained by PCR analysis.

METHODS

Eighty nine bone marrow biopsies displaying lymphoid infiltrates were evaluated by morphology and immunohistochemistry as well as by CDR3-PCR using consensus framework 3 (FRW3) and JH primers.

RESULTS

The presence of a clonal B cell proliferation was demonstrated by PCR analysis in 45 biopsies, including 21 samples considered to be positive, 17 to be suspicious, and seven to be negative by morphology. In the remaining 44 trephines we found no evidence of clonality, although 12 of these trephines were thought to be positive by morphology.

CONCLUSIONS

These results, revealing an incomplete correlation between CDR3-PCR data and immunomorphological findings, indicate that molecular analysis may be more sensitive and specific in general. However, false negative PCR results do occur, which emphasises the necessity to combine both diagnostic tools in the evaluation of lymphoid infiltrates.

Small B-cell lymphoproliferative disorders: an overview of diagnostic approach

Despite their common origin from the B-cell mature lymphoid system, small B-cell lymphomas/leukaemias represent in fact an heterogeneous group of diseases. Recent advances in immunohistochemistry and molecular techniques have improved our knowledge of the immune system and lymphoid neoplasms. An international consensus has been recently reached among pathologists and clinicians, that recognises clinico-pathological entities which are defined by a combination of morphological, immunophenotypical, genetic and clinical features. In each entity, a range of histological grade and clinical aggressiveness can be encountered. Recognition of these entities, combined with clinical prognostic factors has clinical implications in terms of response to treatment and prognosis. The purpose of this paper is to focus on a practical approach, either clinical or pathological, of the diagnosis of small B-cell lymphoma/leukaemia.

The product of the t(11;18), an API2-MLT fusion, is an almost exclusive finding in marginal zone cell lymphoma of extranodal MALT-type

BACKGROUND

Extranodal marginal zone cell lymphoma (MZCL) of MALT-type share similar features with nodal and splenic MZCL regarding morphology and immunophenotype. At the genetic level, recent cytogenetic studies have shown that t(11;18) is a recurring abnormality in extranodal MALT-type MZCL but has hitherto never been reported in nodal or splenic MZCL. The aim of the present study was to determine the prevalence of t(11;18) in a large series of nodal, splenic and extranodal MALT-type MZCL, using a sensitive real-time RT-PCR method.

MATERIALS AND METHODS

Ninety-three MZCL cases were divided on clinical grounds into 61 extranodal MALT-type, 19 splenic and 12 nodal MZCL. One case that presented with a massive splenomegaly but for which also gastro-intestinal localisations were found, was left unclassified. A real-time RT-PCR method for the detection of the API2-MLT fusion resulting from t(11;18) was performed on RNA extracted from frozen tissue sections.

RESULTS

The API2-MLT fusion was detected in 12 cases, which were all extranodal MALT-type lymphomas of the stomach, except for one case. The remaining positive case was the unclassified case, for which the translocation was detected in the spleen and in hilar lymph node tissue.

CONCLUSIONS

While similarities between MZCL from different anatomic sites have lend us to propose that all MZCL have a common normal counterpart, the almost exclusive detection of t(11;18) in gastric MALT-type lymphoma favours its recognition as a separate lymphoma entity. The absence of the translocation in nodal and splenic MZCL challenges the idea of these lymphomas being secondary to MALT-type lymphomas of the gut. The unclassified case illustrates the inadequate approaches available at present to identify and define the various MZCL.