Bone marrow histological patterns can predict survival of patients with grade 1 or 2 follicular lymphoma: a study from the Groupe d‘Etude des Lymphomes Folliculaires

Challenges Encountered and Pattern-Based Analysis of Bone Marrow Biopsy in Lymphomas: An Institutional Experience

Objective The evaluation of bone marrow (BM) status is an integral part of the initial workup of patients diagnosed with lymphoma as it plays an important role in staging and predicting prognosis in these patients. This article determines the incidence and pattern of BM involvement in lymphoma cases and distinguishes benign from malignant lymphoid aggregates in BM biopsies.

Materials and Methods The study group included 121 cases of Hodgkin and non-Hodgkin lymphomas for which BM biopsies were performed, fixed in acetic acid-zinc formalin solution, decalcified using 10% formic acid, and subjected to hematoxylin and eosin and immunohistochemistry.

Results The overall incidence of BM biopsy involvement in our study was 31.4% (37/118), including 34.7% (35/101) in cases of B cell lymphomas, 25% (2/8) in cases of T cell lymphomas, and no involvement in Hodgkin lymphoma. The predominant histological pattern of BM involvement was diffused (14/37; 37.8%), followed by interstitial (10/37; 27.1%). Five cases revealed benign nonparatrabecular lymphoid aggregates which could be confused with lymphomatous involvement, especially in low grade lymphomas.

Conclusion A careful examination of the BM biopsies along with clinical history, peripheral blood examination, flow cytometry, and immunohistochemistry will help in arriving at the correct diagnosis.

Past, present and future of prognostic scores in follicular lymphoma

Although most follicular lymphoma (FL) patients have prolonged survival, the identification of those at risk of early progression, multiple relapses or histological transformation is essential for the improvement of long-term outcomes. In this sense, a plethora of prognostic indexes have been developed in the last decades. However, determining which one is more accurate and clinically meaningful remains a challenge. Key factors for the external validity of available indexes include characteristics of the study population, treatment intervention, and design of the study. While initial risk scores were composed of clinical, biochemical, and hematological variables, genomic and imaging data have been incorporated in recent years. Despite an obvious step forward in the knowledge of the natural history and biology of FL, predictions remain inaccurate. Further research will likely incorporate information from circulating tumor DNA and artificial intelligence models to refine the prognostic classification of the heterogeneous FL population.

Comparison of Bone Marrow Involvement with Bone Marrow Biopsy and PET-CT and Evaluation of Any Effects on Survival in Patients Diagnosed with Hodgkin and Non-Hodgkin Lymphoma

We aimed to demonstrate whether PET-CT can replace bone marrow biopsy in detecting bone marrow involvement in subtypes of lymphoma. In addition, we aimed to also reveal whether there is a difference between the mean survival of patients with bone marrow involvement via PET-CT or biopsy. A total of 276 newly diagnosed lymphoma patients who underwent bone marrow biopsy and PET-CT prior to the treatment were scanned retrospectively. Bone marrow biopsy was used as the standard method to investigate the presence of bone marrow involvement in PET-CT. The relationship between bone marrow involvement and mean survival was compared using both methods. Out of the 276 patients, bone marrow involvement was detected with PET-CT and with biopsy, respectively in 56 patients (20.2%) and in 78 patients (28.2%). In terms of PET-CT's accuracy with respect to revealing bone marrow involvement, the highest rates were achieved respectively in diffuse large B cell lymphoma (DLBCL) (87.4%) and Hodgkin lymphoma (HL) (77.7%). In both the PET-CT and bone marrow biopsy methods, Overall Survival (OS) was found to be significantly shorter in patients with involvement than in patients without involvement (P: 0.001). PET-CT may replace bone marrow (BM) biopsy in detecting the bone marrow involvement in aggressive lymphoma subtypes such as DLBCL and HL. The presence of BM involvement at the time of diagnosis in both PET-CT and BM biopsy is associated with poor prognosis, and OS is short in this group.

Treatment outcomes and clinical relevance of the Follicular Lymphoma International Prognostic Index in Korean follicular lymphoma patients treated with chemotherapy

BACKGROUND/AIMS

The Follicular Lymphoma International Prognostic Index (FLIPI) and FLIPI2 are well-known prognostic models for patients with follicular lymphoma (FL). However, their prognostic relevance has not been examined before in Korean patients with FL.

METHODS

We reviewed clinical and laboratory information from our database of patients between 1995 and 2012. In total, 125 patients were stratified in three categories according to FLIPI or FLIPI2 scores: low-, intermediate-, and high-risk groups. We compared FLIPI and FLIPI2 in terms of progression-free survival (PFS) and overall survival (OS).

RESULTS

Among the 125 patients, the prognostic value of FLIPI and FLIPI2 was evaluated in 73 patients who fulfilled the criteria of both prognostic models. Risk stratification by FLIPI and FLIPI2 showed significant differences in unfavorable parameters among each risk group, particularly between low- and intermediate-risk groups. The high-risk group b was significantly associated with poor PFS on both FLIPI and FLIPI2 (p < 0.05). However, the OS was significantly different only in the risk groups determined by FLIPI2 (p = 0.042). In a subgroup analysis of patients who received rituximab-containing chemotherapy, the risk stratification of both prognostic models showed a significant impact on PFS, especially in the low-risk group.

CONCLUSIONS

FLIPI and FLIPI2 are appropriate prognostic models in Korean FL patients, especially for discriminating low-risk patients from intermediate- and high-risk groups.

Bone marrow trephine biopsy involvement by lymphoma: pattern of involvement and concordance with flow cytometry, in 10 years from a single institution

PURPOSE

To evaluate the features of bone marrow (BM) biopsy involvement by lymphoma, pattern of infiltration, morphological analysis and flow cytometry were reviewed at all lymphoma patients over a period of 10 years.

METHODS/PATIENTS

413 cases were included in the study if BM biopsy slides were available. Only 356 patients had both BM trephine biopsy and flow cytometry.

RESULTS

The most frequent subtype was diffuse large B cell (31.2%), followed by follicular lymphoma (18.9%). The predominant pattern was mixed (nodular-interstitial) (9.2%). Morphological marrow infiltration was found in 138 cases, and flow cytometry identified 117 cases with BM involvement. A concordance between the two methods was detected in 305 cases (85.7%). There was discordance in 51 cases (14.3%): morphology positive/FC negative in 33 cases and morphology negative/FC positive in 18.

CONCLUSIONS

Flow cytometry is slightly more useful in detecting involvement when the BM is affected, but this finding is not conclusive.

Prognostic value of bone marrow involvement by clonal immunoglobulin gene rearrangements in follicular lymphoma

Aims

We aimed to evaluate the prognostic value of routine use of PCR amplification of immunoglobulin gene rearrangements in bone marrow (BM) staging in patients with follicular lymphoma (FL).

Methods

Clonal rearrangements were assessed by immunoglobulin heavy and light-chain gene rearrangement analysis in BM aspirates from 96 patients diagnosed with FL and related to morphological detection of BM involvement in biopsies. In 71 patients, results were also compared with concurrent flow cytometry analysis.

Results

BM involvement was detected by PCR in 34.4% (33/96) of patients. The presence of clonal rearrangements by PCR was associated with advanced clinical stage (I–III vs IV; p<0.001), high FL International Prognostic Index (FLIPI) score (0–1, 2 vs ≥3; p=0.003), and detection of BM involvement by morphology and flow cytometry analysis (p<0.001 for both). PCR-positive patients had a significantly poorer survival than PCR-negative patients (p=0.001, log-rank test). Thirteen patients positive by PCR but without morphologically detectable BM involvement, had significantly poorer survival than patients with negative morphology and negative PCR result (p=0.002). The poor survival associated with BM involvement by PCR was independent of the FLIPI score (p=0.007, Cox regression). BM involvement by morphology or flow cytometry did not show a significant impact on survival.

Conclusions

Our results showed that routine use of PCR-based clonality analysis significantly improved the prognostic impact of BM staging in patients with FL. BM involvement by PCR was also an independent adverse prognostic factor.

Stromal cell contribution to human follicular lymphoma pathogenesis

Follicular lymphoma (FL) is the prototypical model of indolent B cell lymphoma displaying a strong dependence on a specialized cell microenvironment mimicking normal germinal center. Within malignant cell niches in invaded lymph nodes and bone marrow, external stimuli provided by infiltrating stromal cells make a pivotal contribution to disease development, progression, and drug resistance. The crosstalk between FL B cells and stromal cells is bidirectional, causing activation of both partners. In agreement, FL stromal cells exhibit specific phenotypic, transcriptomic, and functional properties. This review highlights the critical pathways involved in the direct tumor-promoting activity of stromal cells but also their role in the organization of FL cell niche through the recruitment of accessory immune cells and their polarization to a B cell supportive phenotype. Finally, deciphering the interplay between stromal cells and FL cells provides potential new therapeutic targets with the aim to mobilize malignant cells outside their protective microenvironment and increase their sensitivity to conventional treatment.

Mesenchymal stromal cells orchestrate follicular lymphoma cell niche through the CCL2-dependent recruitment and polarization of monocytes

Accumulating evidence indicates that infiltrating stromal cells contribute directly and indirectly to tumor growth in a wide range of cancers. In follicular lymphoma (FL), malignant B cells are found admixed with heterogeneous lymphoid-like stromal cells within invaded lymph nodes and BM. In addition, mesenchymal stromal cells (MSCs) support in vitro FL B-cell survival, in particular after their engagement toward lymphoid differentiation. We show here that BM-MSCs obtained from patients with FL (FL-MSCs) display a specific gene expression profile compared with MSCs obtained from healthy age-matched donors (HD-MSCs). This FL-MSC signature is significantly enriched for genes associated with a lymphoid-like commitment. Interestingly, CCL2 could be detected at a high level within the FL-cell niche, is up-regulated in HD-MSCs by coculture with malignant B cells, and is overexpressed by FL-MSCs, in agreement with their capacity to recruit monocytes more efficiently than HD-MSCs. Moreover, FL-MSCs and macrophages cooperate to sustain malignant B-cell growth, whereas FL-MSCs drive monocyte differentiation toward a proangiogenic and lipopolysaccharide-unresponsive phenotype close to that of tumor-associated macrophages. Altogether, these results highlight the complex role of FL stromal cells that promote direct tumor B-cell growth and orchestrate FL-cell niche, thus emerging as a potential therapeutic target in this disease.

Prognostic Factors in Follicular Lymphoma

Follicular lymphoma (FL) is one of the most common types of non-Hodgkin's lymphoma. It is usually diagnosed at an advanced stage, for which many treatment options exist, however, no curative standard therapy has been identified. The outcome is highly variable with a median survival of approximately 10 years. The life expectancy of patients with FL has been extended with the use of rituximab, a monoclonal antibody targeting the CD20 antigen on FL cells, but there remains a group of patients who fail to respond to chemoimmunotherapy and die early of their disease. Transformation of FL to an aggressive histology is an important event with high morbidity and mortality. The Follicular Lymphoma International Prognostic Index has become the clinically useful prognostic tool, but gives only a rough estimate of expected outcome. There is a need for useful biomarkers for prediction of the disease course of single patients to individualize therapy, especially in the new era of chemoimmunotherapy.

Bone marrow involvement by hodgkin and non-hodgkin lymphomas

Bone marrow evaluation plays a critical role in staging and predicting prognosis in patients with Hodgkin lymphoma or non-Hodgkin lymphoma. Bone marrow can be the initial site of detection of lymphoma in patients with unexplained symptoms or cytopenias. A comprehensive evaluation of bone marrow includes complete blood counts, blood morphology, bone marrow aspirate, and generous core biopsy sections. Specialized testing should be used in a logical fashion on a case by case basis.

Expression of activation-induced cytidine deaminase in malignant lymphomas infiltrating the bone marrow

Somatic hypermutation of immunoglobulin genes and class switch recombination are pivotal processes in the germinal center (GC) reaction and have been implicated in the development of malignant B-cell lymphoma. Both processes require the enzyme activation-induced cytidine deaminase (AID). Expression of AID is largely restricted to GC B cells and B cells that undergo class switch recombination outside the GC. AID is also expressed in many B-cell lymphomas. This study investigates the expression of AID of malignant lymphomas infiltrating the bone marrow. Bone marrow trephines (n=130) with infiltration of Hodgkin lymphoma and non-Hodgkin lymphoma of B cell and T-cell type and trephines with reactive lymphoid follicles (n=16) were analyzed immunohistochemically for AID protein. AID is expressed in bone marrow infiltrates of malignant lymphomas. AID was generally detected in lymphomas of GC origin. Tumor cells of hairy cell leukemia are mostly AID. There is apparently no different expression of AID found in bone marrow infiltrates of malignant lymphomas compared with a control group with nodal malignant lymphoma infiltrates (n=105). These results suggest that the expression pattern of AID in lymphoma infiltrates in the bone marrow reflects that of extramedullary lymphoma infiltrates.

Functional alteration of the lymphoma stromal cell niche by the cytokine context: role of indoleamine-2,3 dioxygenase

Human mesenchymal stem cells (MSC) strongly repress activated T-cell proliferation through the production of a complex set of soluble factors, including the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO), which is induced by IFN-gamma. Conversely, MSCs support survival of follicular lymphoma (FL) B cells, in particular after exposure to tumor necrosis factor-alpha (TNF) and lymphotoxin-alpha1beta2 (LT). The role of MSCs on normal and malignant B-cell growth in steady-state and inflammatory conditions remains to be fully explored. We show here that resting MSCs sustain activated normal B-cell proliferation and survival, whereas IFN-gamma-conditioned MSCs mediate IDO-dependent B-cell growth arrest and apoptosis. IFN-gamma, TNF, and LT are significantly overexpressed by the microenvironment of invaded FL-lymph nodes, but their relative expression patterns are highly heterogeneous between samples. In vitro, IFN-gamma abrogates the B-cell supportive phenotype induced by TNF and LT on MSCs. Moreover, IFN-gamma overrules the growth promoting effect of MSCs on primary purified FL B cells. Altogether, these results underline the crucial role of the cytokine context in the local crosstalk between malignant cells and their microenvironment and provide new insights into our knowledge of the FL cell niche that emerges as a new promising target for innovative therapeutic strategies.

Histopathological bone marrow changes after reduced-intensity hematopoietic stem cell transplantation for follicular lymphoma involving bone marrow

Allogeneic stem cell transplantation (allo-SCT) is used as curative therapy for malignant lymphoma, and reduced-intensity hematopoietic stem cell transplantation (RIST) is sometimes performed to avoid the toxicity and mortality associated with myeloablative allo-SCT. RIST is generally preferred for elderly patients with malignant lymphoma. A 62-year-old woman with follicular lymphoma (FL) involving bone marrow (BM) suffered relapse after autologous SCT. RIST was performed; cells were from an unrelated, fully human leukocyte antigen-matched donor. To study the hematopoietic reconstitution, BM biopsy specimens that were obtained at different times after RIST, were evaluated. Engraftment of donor cells was observed on days 19 and 48 after RIST, and residual FL in BM had completely disappeared by day 73 after RIST. This is the first report to document histological BM regeneration after RIST and disappearance of FL involving the BM.

Follicular Lymphoma in Staging Bone Marrow Specimens: Correlation of Histologic Findings With the Results of Flow Cytometry Immunophenotypic Analysis

Context.—Bone marrow (BM) examination is part of the staging workup of lymphoma patients. Few studies have compared BM histologic findings with results of flow cytometric immunophenotyping analysis in follicular lymphoma (FL) patients.

Objective.—To correlate histologic findings with immunophenotypic data in staging BM biopsy and aspiration specimens of FL patients.

Design.—Bone marrow biopsy specimens of untreated FL patients were reviewed. Histologic findings were correlated with 3-color flow cytometric immunophenotyping results on corresponding BM aspirates.

Results.—Bone marrow biopsy specimens (with or without aspirates) of 114 patients with histologic evidence of FL in BM were reviewed. There were 76 bilateral and 38 unilateral biopsies performed, resulting in 190 specimens: 187 involved by FL and 3 negative (in patients with a positive contralateral specimen). The extent of BM involvement was &lt;5% in 32 (17.1%), ≥5% and ≤25% in 102 (54.6%), &gt;25% and ≤50% in 27 (14.4%), and &gt;50% in 26 (13.9%) specimens. The pattern of involvement was purely paratrabecular in 81 (43.3%), mixed in 80 (42.8%), and purely nonparatrabecular in 26 (13.9%). Immunophenotyping was only performed unilaterally, on BM aspirates of 92 patients, and was positive for a monoclonal B-cell population in 53 (57.6%) patients. Immunophenotyping was more often negative when biopsy specimens showed FL with a purely paratrabecular pattern. For comparison, we assessed 163 FL patients without histologic evidence of FL in BM also analyzed by flow cytometric immunophenotyping. A monoclonal B-cell population was identified in 5 patients (3%).

Conclusions.—Our data suggest that 3-color flow cytometric immunophenotyping adds little information to the evaluation of staging BM specimens of FL patients.

Clinical and molecular prognostic factors in follicular lymphoma

The observed variability in the clinical course of follicular lymphoma (FL), along with the diverse range of therapeutic options available, necessitates accurate prognostic stratification of the individual patient. A number of clinical, laboratory, and pathologic parameters have been associated with both good and poor risk disease; in some instances these have been incorporated into readily calculable prognostic indices. With new insights into disease biology and the resulting identification of biomarkers that have arisen from the analysis of both the genome and the transcriptome, more accurate individualization of prognosis will be realized. At present the clinical application of such biomarkers, however, remains largely in its infancy. This review examines the clinical and molecular prognostic features that have been identified as of value in FL.

Human mesenchymal stem cells isolated from bone marrow and lymphoid organs support tumor B-cell growth: role of stromal cells in follicular lymphoma pathogenesis

Accumulating evidence indicates that the cellular microenvironment plays a key role in follicular lymphoma (FL) pathogenesis, both within tumor lymph nodes (LNs) and in infiltrated bone marrow where ectopic LN-like reticular cells are integrated within malignant B-cell nodular aggregates. In normal secondary lymphoid organs, specific stromal cell subsets provide a highly specialized microenvironment that supports immune response. In particular, fibroblastic reticular cells (FRCs) mediate immune cell migration, adhesion, and reciprocal interactions. The role of FRCs and their postulated progenitors, that is, bone marrow mesenchymal stem cells (MSCs), in FL remains unexplored. In this study, we investigated the relationships between FRCs and MSCs and their capacity to sustain malignant B-cell growth. Our findings strongly suggest that secondary lymphoid organs contain MSCs able to give rise to adipocytes, chondrocytes, osteoblasts, as well as fully functional B-cell supportive FRCs. In vitro, bone marrow-derived MSCs acquire a complete FRC phenotype in response to a combination of tumor necrosis factor-alpha and lymphotoxin-alpha1beta2. Moreover, MSCs recruit primary FL cells that, in turn, trigger their differentiation into FRCs, making them able to support malignant B-cell survival. Altogether, these new insights into the cross talk between lymphoma cells and their microenvironment could offer original therapeutic strategies.

Grading of follicular lymphoma using flow cytometry

BACKGROUND

The treatment and prognosis of follicular lymphoma (FL) is dependant on the grade of the disease. In the World Health Organization classification of lymphoma, grading of FL into low grade (1 and 2) and high grade (3) is recommended. Grading of FL is possible in excision biopsy; histological grading is subjective and inconsistent. Grading is extremely difficult in needle core biopsies and fine needle aspirates. We attempted to grade FL using flow cytometry (FCM) and CD19/ forward scatter.

MATERIALS AND METHODS

Cases of FL seen in our institution and submitted for FCM were evaluated for the percentage of cells detected beyond the 500-channel mark (on a 1024 scale) on a CD19/forward scatter dot plot. We hypothesized that these cells most likely represent centroblasts and their percentage would reflect the grade of the disease. Histological grading of the lymphoma on the open biopsies constituted the reference for FL grade.

RESULTS

Thirty-six cases of FL, including 22 males and 14 females, ranging in age from 19 to 92 years (median, 42 years), were studied. There were 17 cases of low grade (grade 1; n=10 and grade 2; n=7) and 19 cases of high grade (grade 3) FL. The percentage of cells identified beyond the 500-channel mark on CD19/forward scatter dot plot ranged from 0.12% to 12.55% (median, 4.9%) in low grade (grade 1 and 2) whereas the percentage of those cells in high grade FL ranged from 6.22% to 51.95% (median, 21%; P=0.00001).

CONCLUSION

Our findings suggest that using a CD19/forward scatter dot plot can help identify centroblasts in FL making grading possible on FCM, especially in small biopsies and fine needle aspirates.

Bone Marrow Biopsy Involvement by Non-Hodgkin's Lymphoma

To evaluate the features of bone trephine biopsy involvement by non-Hodgkin lymphoma, 450 specimens were evaluated for percentage of marrow involvement, pattern of involvement, presence of germinal centers or follicular structures, and discordance with other involved sites. A subset of 197 cases was evaluated for evidence of concurrent peripheral blood involvement. Follicular grade 1 lymphoma (30.4%) was the most common type to involve the marrow, followed by diffuse large B-cell lymphoma (16.0%), mantle cell lymphoma (9.3%), low-grade B-cell lymphoma, not otherwise specified (8.7%), lymphoplasmacytic lymphoma (8.4%), follicular grade 2 lymphoma (7.1%), and mature T- and NK-cell lymphomas (6.4%). A mixed pattern of infiltration was most common, followed by paratrabecular, nodular, diffuse, and interstitial patterns. Greater than 90% of follicular lymphomas had at least a focal paratrabecular infiltration pattern, but this pattern was also seen with other lymphoma types. Interstitial disease infiltration tended to correlate with lymphoplasmacytic lymphoma but was also not specific. The presence of germinal centers or follicular structures was associated with follicular lymphoma in 88% of cases. Discordance between the bone marrow morphology and other tissue sites was observed in 24.9% of cases and was most often seen with follicular or diffuse large B-cell lymphoma. Peripheral blood involvement by lymphoma was observed in 29% of cases, found in all disease groups except for follicular grade 3 lymphoma. This study highlights the frequency of different lymphoma patterns in the marrow, limitations of primary lymphoma classification on biopsy material alone, and the relative frequency of marrow discordance and peripheral blood involvement by marrow lymphoma.

Clonal selection in the bone marrow involvement of follicular lymphoma

To characterize the pathways of bone marrow (BM) involvement of follicular lymphoma (FL), we performed morphological and immunophenotypical analysis of tumor cells from lymph nodes (LNs) and corresponding BMs in 21 patients with FL. In three cases, genealogical trees were constructed based on the immunoglobulin variable region heavy chain (IgV(H)) gene sequences of tumor clones from LNs and BMs. Results showed that FLs within the BMs display identical or lower cytological grades than in the LNs. In the majority of cases, different proportions of tumor cells expressed bcl-2, CD10 and Ki67 in LNs and BMs. Tumor cells in the BM showed ongoing somatic hypermutation of the IgV(H) genes; the distribution of these mutations was highly consistent with antigen selection. The topology of the genealogical trees revealed that different subclones populate the LN and BM and BM infiltration may occur at different points of the clonal evolution of FL. Early descendants of the original tumor clone and derivatives of diversified tumor clones may invade the BM. These results suggest that the BM involvement of FL is associated with intensive clonal selection of tumor cells, and the BM provides a microenvironment similar to the germinal centers of LNs, where tumor cells retain their biological nature.