Assessment of bone marrow plasma cell infiltrates in multiple myeloma: the added value of CD138 immunohistochemistry

Advances in estimating plasma cells in bone marrow: A comprehensive method review

The quantitation of plasma cells in bone marrow (BM) is crucial for diagnosing and classifying plasma cell neoplasms. Various methods, including Romanowsky-stained BM aspirates (BMA), immunohistochemistry, flow cytometry, and radiological imaging, have been explored. However, challenges such as patchy infiltration and sample haemodilution can impact the reliability of BM plasma cell percentage estimates. Bone marrow plasma cell percentage varies across methods, with immunohistochemically stained biopsies consistently yielding higher values than Romanowsky-stained BMA or flow cytometry alone. CD138 or MUM1 immunohistochemistry and artificial intelligence image analysis on whole-slide images are emerging as promising tools for accurate plasma cell identification and quantification. Radiological imaging, particularly with advanced technologies like dual-energy computed tomography and radiomics, shows potential for multiple myeloma diagnosis, although standardisation remains a challenge. Molecular techniques, such as allele-specific oligonucleotide quantitative polymerase chain reaction and next-generation sequencing, offer insights into clonality and measurable residual disease. While no consensus exists on a gold standard method for BM plasma cell quantitation, CD138-stained biopsies are favoured for accurate estimation and play a pivotal role in diagnosing and assessing multiple myeloma treatment responses. Combining multiple methods, such as BMA, BM biopsy, and flow cytometry, enhances accuracy of diagnosis and classification of plasma cell neoplasms. The quest for a gold standard requires ongoing research and collaboration to refine existing methods. Furthermore, the rise of digital pathology is anticipated to reshape laboratory medicine and the role of pathologists in the digital era.

What this study adds

This article adds a comprehensive review and comparison of different methods for plasma cell estimation in the bone marrow, highlighting their strengths and limitations. The goal is to contribute valuable insights that can guide the selection of optimal techniques for accurate plasma cell estimation.

Evaluation of a new technique using artificial intelligence for quantification of plasma cells on CD138 immunohistochemistry

INTRODUCTION

The diagnosis of plasma cell neoplasms depends on the accurate quantification of plasma cells, traditionally done by immunohistochemical CD138 staining of bone marrow biopsies. Currently, there is no fully satisfactory reference method for this quantification. In our previous study, we compared the commonly used overview estimation method (method A) with a novel method for counting plasma cells in three representative areas (method B). Results showed comparable concordance parameters between the two methods. In this follow-up study, we compared the previously evaluated methods with a digital analysis method (method C) that uses artificial intelligence in open-source software, QuPath.

METHODS

Archived CD138 immunohistochemically stained trephine sections of bone marrow samples used in our previous study were used (n = 33). Reviewers selected three representative areas on each sample by taking images with a light microscope and camera. Digital analysis was performed using the positive cell detection function in QuPath. The entire process was repeated by each reviewer to test intraobserver concordance (concordance correlation coefficient [CCC]) in addition to interobserver concordance (intraclass correlation coefficient [ICC]).

RESULTS

Intraobserver concordance of method C showed strong agreement for all reviewers with the lowest CCC = 0.854. Interobserver concordance for method C using ICC was 0.909 and 0.949. This showed high interobserver agreement with significant differences between method C and previously assessed method A (ICC = 0.793 and 0.713) and method B (ICC = 0.657 and 0.658).

CONCLUSION

We were able to successfully count CD138-positive plasma cells in bone marrow biopsies using artificial intelligence. This method is superior to both manual counting and overview estimation, regardless of tumour load.

Evaluation of an innovative new method for quantitation of plasma cells on CD138 immunohistochemistry

AIM

To compare the frequently used CD138 immunohistochemistry-based method of plasma cell quantitation, to a proposed new method, using interobserver and intraobserver concordance parameters.

METHODS

Archival CD138 immunohistochemically stained slides made from paraffin-embedded bone marrow biopsies of 33 patients with a confirmed diagnosis of multiple myeloma were used. Light microscopic examination was performed using low magnification lenses (10×) for both the overview estimation method (method A) and the new method (method B), and high magnification lenses (50×), for method B only. For method B, reviewers selected three areas with low, intermediate and high plasma cell densities using 10× lenses. Using a well-defined technique, the 50× lens was then used to count plasma cells as a percentage of all nucleated cells. After blinded relabelling of all the slides, the nine reviewers repeated the plasma cell quantitation using both methods. The plasma cell counts were obtained, and the review times were recorded.

RESULTS

Overall intraobserver concordance was comparable for method A (concordance correlation coefficient (CCC)=0.840) and method B (CCC=0.733). Interobserver concordance for method A (intraclass correlation coefficient (ICC)=0.793 and 0.713) and method B (ICC=0.657 and 0.658) indicated high similarity between reviewers. Method A showed poor interobserver concordance (ICC=0.105) at low plasma cell densities.

CONCLUSIONS

The new method is comparable to the frequently used overview estimation method in terms of intraobserver and interobserver concordance, and cost. The new method has superior interobserver concordance at low plasma cell densities. The new method appears more amenable to digital scanning and analysis.

How I approach smoldering multiple myeloma

The current standard of care in smoldering multiple myeloma (SMM) is close surveillance, outside of clinical trials. Efforts are being made to understand the pathobiologic process that leads to the progression of SMM to active MM. This review provides a critical description of available data, including risk factors and risk models of progression, as well as clinical trials investigating interventions for this patient population. We describe 2 cases in which patients were seen before the concept of a myeloma-defining event was established. Today, based on the International Myeloma Working Group criteria, both patients would have been identified as experiencing myeloma-defining events, and therapy would have been initiated. These cases show that occasionally, patients can undergo observation only, even when they exceed criteria for high-risk SMM.

Evaluation of multiple myeloma measurable residual disease by high sensitivity flow cytometry: An international harmonized approach for data analysis

BACKGROUND

Multiple myeloma (MM) measurable residual disease (MRD) evaluated by flow cytometry is a surrogate for progression-free and overall survival in clinical trials. However, analysis and reporting between centers lack uniformity. We designed and evaluated a consensus protocol for MM MRD analysis to reduce inter-laboratory variation in MM MRD reporting.

METHODS

Seventeen participants from 13 countries performed blinded analysis of the same eight de-identified flow cytometry files from patients with/without MRD using their own method (Stage 1). A consensus gating protocol was then designed following survey and discussions, and the data re-analyzed for MRD and other bone marrow cells (Stage 2). Inter-laboratory variation using the consensus strategy was reassessed for another 10 cases and compared with earlier results (Stage 3).

RESULTS

In Stage 1, participants agreed on MRD+/MRD- status 89% and 68% of the time respectively. Inter-observer variation was high for total numbers of analyzed cells, total and normal plasma cells (PCs), limit of detection, lower limit of quantification, and enumeration of cell populations that determine sample adequacy. The identification of abnormal PCs remained relatively consistent. By consensus method, average agreement on MRD- status improved to 74%. Better consistency enumerating all parameters among operators resulted in near-unanimous agreement on sample adequacy.

CONCLUSION

Uniform flow cytometry data analysis substantially reduced inter-laboratory variation in reporting multiple components of the MM MRD assay. Adoption of a harmonized approach would meet an important need for conformity in reporting MM MRD for clinical trials, and wider acceptance of MM MRD as a surrogate clinical endpoint.

Deep Learning Accurately Quantifies Plasma Cell Percentages on CD138-Stained Bone Marrow Samples

The diagnosis of plasma cell neoplasms requires accurate, and ideally precise, percentages. This plasma cell percentage is often determined by visual estimation of CD138-stained bone marrow biopsies and clot sections. While not necessarily inaccurate, estimates are by definition imprecise. For this study, we hypothesized that deep learning can be used to improve precision. We trained a semantic segmentation-based convolutional neural network (CNN) using annotations of CD138+ and CD138- cells provided by one pathologist on small image patches of bone marrow and validated the CNN on an independent test set of image patches using annotations from two pathologists and a non-deep learning commercial software. On validation, we found that the intraclass correlation coefficients for plasma cell percentages between the CNN and pathologist #1, a non-deep learning commercial software and pathologist #1, and pathologists #1 and #2 were 0.975, 0.892, and 0.994, respectively. The overall results show that CNN labels were almost as accurate as pathologist labels at a cell-by-cell level. Once satisfied with performance, we scaled-up the CNN to evaluate whole slide images (WSIs), and deployed the system as a workflow friendly web application to measure plasma cell percentages using snapshots taken from microscope cameras.

Harmonization of Flow Cytometric Minimal Residual Disease Assessment in Multiple Myeloma in Centers of Polish Myeloma Consortium

Minimal residual disease (MRD) status is now considered as one of the most relevant prognostic factors in multiple myeloma (MM) while MRD negativity became an important endpoint in clinical trials. Here, we report the results of the first study evaluating the reproducibility of high-sensitivity flow cytometry MM MRD assessment in four laboratories in Poland. EuroFlow protocols for instrument setting standardization and sample preparation in MM MRD assessment were implemented in each laboratory. In the inter-laboratory reproducibility study, 12 bone marrow samples from MM patients were distributed and processed in participant laboratories. In the inter-operator concordance study, 13 raw data files from MM MRD measurements were analyzed by five independent operators. The inter-laboratory study showed high 95% overall concordance of results among laboratories. In the inter-operator study, 89% of MRD results reported were concordant, and the highest immunophenotype interpretation differences with regard to expression of CD27, CD45, CD81 were noticed. We confirmed the applicability and feasibility of the EuroFlow protocol as a highly sensitive method of MRD evaluation in MM. Results of our inter-center comparison study demonstrate that the standardization of MM MRD assessment protocols is highly desirable to improve quality and comparability of results within and between different clinical trials.

Evaluation of measurable residual disease in multiple myeloma by multiparametric flow cytometry: Current paradigm, guidelines, and future applications

Multiple myeloma (MM) is a heterogeneous group of mature B-cell diseases that are typically characterized by the presence and accumulation of abnormal plasma cells (PCs), which results in the excess production of monoclonal immunoglobulin and/or light chain found in the serum and/or urine. Multiparametric flow cytometry (MFC) is an indispensable tool to supplement the diagnosis, classification and monitoring of the disease due to its high patient applicability, excellent sensitivity and encouraging results from various clinical trials. In this regard, minimal or, more appropriately, measurable residual disease (MRD) negativity by MFC has been recognized as a powerful predictor of favourable long-term outcomes. Before flow cytometry can be effectively implemented in the clinical setting for MM MRD testing, sample preparation, panel configuration, analysis and gating strategies must be optimized to ensure accurate results. This manuscript will discuss the current consensus guidelines for flow cytometric processing of samples and reporting of results for MM MRD testing. We also discuss alternative approaches to detect plasma cells in the presence of daratumumab treatment. Finally, there is a lack of information describing the subclonal distribution of myeloma cells based on their protein expression. The advent of high-dimensional analysis may assist in following the evolution of antigen expression patterns on abnormal plasma cells in patients with relapsed/refractory disease. This in turn can help identify clonal subtypes that are more aggressive for potential informed decision. An analysis using t-SNE to identify the emergence of PCs subclones by MFC, along with the analysis of their immunophenotypic profiles are presented as a future perspective.

Utility of Flow Cytometry and Fluorescence In Situ Hybridization in Follow-up Monitoring of Plasma Cell Myeloma

OBJECTIVES

We sought to investigate the clinical utility of flow cytometry (FC) and fluorescence in situ hybridization (FISH) in the workup of myeloma.

METHODS

We retrospectively reviewed the reports of bone marrow biopsies received for myeloma evaluation between October 2015 and January 2019.

RESULTS

A total of 1,708 biopsy specimens from 469 myeloma patients (mean age, 64.5 years [SD, 9.3]; female, 41.4%) were reviewed. Both FC and FISH had comparable detection rates at the time of initial diagnosis (97.6% vs 98.8%) and for follow-up cases (28.6% vs 28.2%). FC and FISH results were concordant in 98.8% of the initial diagnosis cases and 89.6% of the follow-up cases. The FISH-positive (FISH+)/FC-negative (FC-) discordance and FISH-/FC+ discordance occurred among 81 (5.0%) and 87 (5.4%) follow-up cases. In comparison with all concordant cases, FISH+/FC- discordant cases were more likely to have received treatment with daratumumab (P < .05).

CONCLUSIONS

Plasma cell-enriched FISH and FC have comparable abnormal plasma cell detection rates, and approximately 10% of the follow-up cases have discordant FISH and FC results in which residual disease is detected by only one of these modalities. FISH testing should be considered for cases with negative FC, especially in patients who have received treatment with daratumumab or in cases in which there is concern about specimen adequacy.

Serum BCMA levels predict outcomes in MGUS and smoldering myeloma patients

Soluble BCMA (sBCMA) levels are elevated in monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM). However, the association between sBCMA levels and prognosis in MGUS and SMM has not been studied. We retrospectively analyzed sBCMA levels in stored samples from 99 MGUS and 184 SMM patients. Baseline sBCMA levels were significantly higher in MGUS and SMM patients progressing to MM during clinical follow up. When stratified according to the median baseline sBCMA level for each cohort, higher levels were associated with a shorter PFS for MGUS (HR 3.44 comparing sBCMA ≥77 vs <77 ng/mL [95% CI 2.07-5.73, p < 0.001] and SMM (HR 2.0 comparing sBCMA ≥128 vs <128 ng/mL, 95% 1.45-2.76, p < 0.001) patients. The effect of sBCMA on PFS was similar even after adjusting for the baseline MGUS or SMM risk stratification. We evaluated paired serum samples and found that sBCMA increased significantly in MGUS and SMM patients who eventually progressed to MM, whereas among MGUS non-progressors the sBCMA level remained stable. While our results require independent validation, they suggest that sBCMA may be a useful biomarker to identify MGUS and SMM patients at increased risk of progression to MM independent of the established risk models.

Evaluation of an open-source machine-learning tool to quantify bone marrow plasma cells

AIMS

The objective of this study was to develop and validate an open-source digital pathology tool, QuPath, to automatically quantify CD138-positive bone marrow plasma cells (BMPCs).

METHODS

We analysed CD138-scanned slides in QuPath. In the initial training phase, manual positive and negative cell counts were performed in representative areas of 10 bone marrow biopsies. Values from the manual counts were used to fine-tune parameters to detect BMPCs, using the positive cell detection and neural network (NN) classifier functions. In the testing phase, whole-slide images in an additional 40 cases were analysed. Output from the NN classifier was compared with two pathologist's estimates of BMPC percentage.

RESULTS

The training set included manual counts ranging from 2403 to 17 287 cells per slide, with a median BMPC percentage of 13% (range: 3.1%-80.7%). In the testing phase, the quantification of plasma cells by image analysis correlated well with manual counting, particularly when restricted to BMPC percentages of <30% (Pearson's r=0.96, p<0.001). Concordance between the NN classifier and the pathologist whole-slide estimates was similarly good, with an intraclass correlation of 0.83 and a weighted kappa for the NN classifier of 0.80 with the first rater and 0.90 with the second rater. This was similar to the weighted kappa between the two human raters (0.81).

CONCLUSIONS

This represents a validated digital pathology tool to assist in automatically and reliably counting BMPC percentage on CD138-stained slides with an acceptable error rate.

Automated digital enumeration of plasma cells in bone marrow trephine biopsies of multiple myeloma

AIMS

Determination of the number of plasma cells in bone marrow biopsies is required for the diagnosis and ongoing evaluation of plasma cell neoplasms. We developed an automated digital enumeration platform to assess plasma cells identified by antigen expression in whole bone marrow sections in multiple myeloma, and compared it with manual assessments.

METHODS

Bone marrow trephine biopsy specimens from 91 patients with multiple myeloma at diagnosis, remission and relapse were stained for CD138 and multiple myeloma oncogene 1 (MUM1). Manual assessment and digital quantification were performed for plasma cells in the entire trephine section. Concordance rates between manual and digital methods were evaluated for each antigen by intraclass correlation analyses (ICC) with associated Spearman's correlations.

RESULTS

The digital platform counted 16 484-1 118 868 cells and the per cent CD138 and MUM1-positive plasma cells ranged from 0.05% to 93.5%. Overall concordance between digital and manual methods was 0.63 for CD138 and 0.89 for MUM1. Concordance was highest with diffuse plasma cell infiltrates (MUM1: ICC=0.90) and lowest when in microaggregates (CD138: ICC=0.13). Manual counts exceeded digital quantifications for both antigens (CD138: mean=26.4%; MUM1: mean=9.7%). Diagnostic or relapse threshold counts, as determined by CD138 manual assessments, were not reached with digital counting for 16 cases (18%).

CONCLUSIONS

Automated digital enumeration of the entire, immunohistochemically stained bone marrow biopsy section can accurately determine plasma cell burden, irrespective of pattern and extent of disease (as low as 0.05%). This increases precision over manual visual assessments which tend to overestimate plasma burden, especially for CD138, and when plasma cells are in clusters.

Clinical, pathological and molecular features of plasmablastic lymphoma arising in the gastrointestinal tract: A review and reappraisal

Plasmablastic lymphoma (PBL) is a CD20-negative large B-cell lymphoma with a plasmacytic phenotype and a dismal prognosis, which has been defined as a distinct entity only in the 2008 WHO Classification of Haematopoietic and Lymphoid Tissue and confirmed in the 2017 Edition. Current knowledge of the biological, clinical and prognostic features of PBL is mostly limited, resulting in diagnostic issues, as well as in lack of standard of care and effective therapeutic options. PBL commonly affects the oral cavity of HIV-positive individuals, however the gastrointestinal (GI) tract is the most common extraoral site, and in this location most patients are HIV-negative. In this review, we focus on the clinical, morphological and prognostic features of PBL arising in the GI tract, in order to improve knowledge on this rare, but aggressive disease.

Prevalence of Syndecan-1 (CD138) Expression in Different Kinds of Human Tumors and Normal Tissues

Syndecan-1 (CD138) is a transmembrane proteoglycan known to be expressed in various normal and malignant tissues. It is of interest because of a possible prognostic role of differential expression in tumors and its role as a target for indatuximab, a monoclonal antibody coupled with a cytotoxic agent. To comprehensively analyze CD138 in normal and neoplastic tissues, we used tissue microarrays (TMAs) for analyzing immunohistochemically detectable CD138 expression in 2,518 tissue samples from 85 different tumor entities and 76 different normal tissue types. The data showed that CD138 expression is abundant in tumors. At least an occasional weak CD138 immunostaining could be detected in 71 of 82 (87%) different tumor types, and 58 entities (71%) had at least one tumor with a strong positivity. In normal tissues, a particularly strong expression was found in normal squamous epithelium of various organs, goblet and columnar cells of the gastrointestinal tract, and in hepatocytes. The highly standardized analysis of most human cancer types resulted in a ranking order of tumors according to the frequency and levels of CD138 expression. CD138 immunostaining was highest in squamous cell carcinomas such as from the esophagus (100%), cervix uteri (79.5%), lung (85.7%), vagina (89.7%) or vulva (73.3%), and in invasive urothelial cancer (76.2%). In adenocarcinomas, CD138 was also high in lung (82.9%) and colorectal cancer (85.3%) but often lower in pancreas (73.3%), stomach (54.2% in intestinal type), or prostate carcinomas (16.3%). CD138 expression was usually low or absent in germ cell tumors, sarcomas, endocrine tumors including thyroid cancer, and neuroendocrine tumors. In summary, the preferential expression in squamous cell carcinomas of various sites makes these cancers prime targets for anti-CD138 treatments once these might become available. Abundant expression in many different normal tissues might pose obstacles to exploiting CD138 as a therapeutic target, however.

Petrous apex non-secretory plasma cell myeloma with aberrant cytokeratin expression

Multiple myeloma is a monoclonal proliferation of plasma cells with common involvement of vertebrae, ribs and skull vault. However, involvement of skull base is relatively uncommon and myeloma manifesting initially as a petrous apex mass is distinctly rare. We report a rare case of non-secretory multiple myeloma in a 52-year-old Egyptian male presenting primarily as a right petrous apex mass with abducens nerve palsy. Additionally, neoplastic cells aberrantly expressed cytokeratin. Although rare, plasma cell myeloma should be considered in the differential diagnosis of petrous apex masses.

Monitoring of Measurable Residual Disease in Multiple Myeloma by Multiparametric Flow Cytometry

Recent interest in high sensitivity multiple myeloma (MM) measurable residual disease (MRD) testing is a direct consequence of the high-quality responses achieved using novel therapeutic agents and better treatment strategies. Traditional diagnostic measures such as immunohistochemistry and morphology have detection sensitivities of only 10^-2 - 10^-3, which do not reliably predict progression free survival (PFS) or overall survival (OS) after these treatments. Contemporary monitoring of MM MRD has switched to more sensitive platforms such as quantitative allele-specific oligonucleotide polymerase chain reaction (ASO-qPCR), next-generation sequencing (NGS), and multiparametric flow cytometry (MFC). Though both ASO-qPCR and NGS have excellent detection sensitivities (10^-5 - 10^-6), both technologies have lower applicability when compared to MFC. Conventional MFC can easily reach a detection sensitivity of 10^-4 and when optimized can achieve a sensitivity of 10^-5 - 10^-6. Current consensus guidelines require a minimum of 2 million and recommend 5 million events be acquired to reach a minimum sensitivity of 10^-5. As conventional immunophenotyping protocols are unable to attain these numbers, alternative MFC staining procedures are required. This manuscript describes two high-sensitivity MFC approaches that can be used for MM MRD testing.

Role of CD138, CD56, and light chain immunohistochemistry in suspected and diagnosed plasma cell myeloma: A prospective study

Introduction:

Plasma cells (PCs) have conventionally been counted on the bone marrow aspirate, and small focal involvement may be missed even on bone marrow biopsy sections.

Material and Methods:

We aimed to study the role of CD138, CD56, anti-κ, and anti-λ immunohistochemistry (IHC) to separate PC myeloma from reactive plasmacytosis and to study the utility of these in cases suspected as myelomas and lacking >10% PCs on bone marrow aspirate. The study comprised 35 diagnosed myelomas, 20 reactive plasmacytosis, and 19 M-band positive suspected myelomas. CD138 IHC was performed on all cases along with CD56, anti-κ, and anti-λ IHC. PCs were counted on CD138-immunostained sections by manual count and by image analysis. In addition, CD56 expression was correlated with clinical features in diagnosed myeloma group.

Results:

In all cases, both manual counts and image analysis, PC counts were significantly higher on the CD138 stained sections than bone marrow aspirates. It was seen that the manual PC counts and image analysis counts were equivalent in diagnosed myeloma cases. CD56 expression was seen in ~62.85% diagnosed myeloma cases while it was negative in cases of reactive plasmacytosis. CD56 expression was significantly higher in patients with lytic lesions (78.26% vs. 21.74%). CD138, anti-κ, and anti-λ IHC also helped classify 11/19 (57.8%) cases correctly.

Conclusion:

The use of CD138 along with the light chain and CD56 IHC adds a high diagnostic value in myeloma patients and suspected myeloma cases. The PCs can be counted manually on the CD138-immunostained sections and correlate well with the counts obtained by image analysis.

Combined Immunohistochemistry after Mass Spectrometry Imaging for Superior Spatial Information

OBJECTIVE

Tissue slides analyzed by MS imaging (MSI) are stained by H&E (Haematoxylin and Eosin) to identify regions of interest. As it can be difficult to identify specific cells of interest by H&E alone, data analysis may be impaired. Immunohistochemistry (IHC) can highlight cells of interest but single or combined IHC on tissue sections analyzed by MSI have not been performed.

METHODS

We performed MSI on bone marrow biopsies from patients with multiple myeloma and stained different antibodies (CD38, CD138, MUM1, kappa- and lambda). A combination of CK5/6/TTF1 and Napsin-A/p40 is stained after MSI on adenocarcinoma and squamous cell carcinoma of the lung. Staining intensities of p40 after MSI and on a serial section are quantified on a tissue microarray (n = 44) by digital analysis.

RESULTS

Digital evaluation reveals weaker staining intensities after MSI as compared to serial sections. Staining quality and quantity after MSI enables to identify cells of interest. On the tissue microarray, one out of 44 tissue specimens shows no staining of p40 after MSI, but weak nuclear staining on a serial section.

CONCLUSION

We demonstrated that single and double IHC staining is feasible on tissue sections previously analyzed by MSI, with decreased staining intensities.

Consensus in the Management of Multiple Myeloma in India at Myeloma State of the Art 2016 Conference

The science of multiple myeloma (MM) and related plasma cell disorders is rapidly evolving with increased understanding of the disease biology and recent approval of the newer drugs widening the therapeutic armamentarium. Despite multiple international guidelines regarding the management of this disease, the practice of managing MM is not uniform amongst Indian physicians. There are challenges in management which are unique to the Indian patients. This review discusses these challenges and the consensus of the nation-wide experts in dealing with the same. We also briefly highlighted the perspective of international experts as discussed in the Myeloma State of the Art conference held in September 2016 at PGI, Chandigarh. An Indian Myeloma Academic Groupe (IMAGe) group was formed to strengthen the research, create awareness about myeloma and related disorders and form consensus guidelines/ recommendations that can be adapted to the Indian Scenario.

Quantification of bone marrow plasma cell infiltration in multiple myeloma: usefulness of bone marrow aspirate clot with CD138 immunohistochemistry

Accurate quantification of plasma cells (PCs) in bone marrow (BM) is critical for diagnosis and assessment of treatment response in patients with multiple myeloma (MM). We compared the % of BM PC quantified by 250 cell differential count on May-Giemsa-stained BM smears, by counting 500 - 2500 cells in 2 - 5 representative microscopy fields in CD138-immunostained BM clot and biopsy sections, and CD38/CD45/CD138 gated BM PCs on flow cytometry (FCM) in 150 sets of BM samples from 120 patients. Percentages of PC were significantly correlated between BM biopsy and clot, and between smear and FCM (r = 0.96, 0.93, respectively). However, quantification by smear and FCM significantly underestimated the PC compared to biopsy or clot, and the degree of underestimation increased with blood dilution. FCM consistently showed lower % of PC compared to aspirate smears. Fifty-nine of 103 patients with M-protein level < 3000 mg/dL in serum or 500 mg/24 h in urine and diagnosed with monoclonal gammopathy of undetermined significance (MGUS) based on smear alone were reclassified as smoldering MM when reassessed using CD138-stained biopsy/clot sections. Among the 72 patients with sMM diagnosed by BM biopsy and/clot, three patients (4.2%) had extensive BM infiltration of PC (≥ 60%) and required treatment. Our data clearly showed the necessity of CD138 immunostaining of BM biopsy/clot specimens for correct diagnosis of MM and related disorders. Copyright © 2016 John Wiley & Sons, Ltd.

An Organotypic High Throughput System for Characterization of Drug Sensitivity of Primary Multiple Myeloma Cells

In this work we describe a novel approach that combines ex vivo drug sensitivity assays and digital image analysis to estimate chemosensitivity and heterogeneity of patient-derived multiple myeloma (MM) cells. This approach consists in seeding primary MM cells freshly extracted from bone marrow aspirates into microfluidic chambers implemented in multi-well plates, each consisting of a reconstruction of the bone marrow microenvironment, including extracellular matrix (collagen or basement membrane matrix) and stroma (patient-derived mesenchymal stem cells) or human-derived endothelial cells (HUVECs). The chambers are drugged with different agents and concentrations, and are imaged sequentially for 96 hr through bright field microscopy, in a motorized microscope equipped with a digital camera. Digital image analysis software detects live and dead cells from presence or absence of membrane motion, and generates curves of change in viability as a function of drug concentration and exposure time. We use a computational model to determine the parameters of chemosensitivity of the tumor population to each drug, as well as the number of sub-populations present as a measure of tumor heterogeneity. These patient-tailored models can then be used to simulate therapeutic regimens and estimate clinical response.

Plasmablastic Lymphoma of Small Intestine: A Rare Case Report with Review of Literature

Plasmablastic lymphoma (PBL) is a rare aggressive neoplasm characterized by diffuse proliferation of large neoplastic cells with plasma cell immunophenotype. Cell of origin of PBL is believed to be a postgerminal center B-lymphocyte or plasmablast. The malignant cells in PBL usually do not express CD20 (B cell marker) but do express markers of plasmacytic differentiation, such as CD38, CD138, or MUM1/IRF4, akin to plasma cell myeloma (PCM). PBL though originally described in the oral cavity, has now been found to occur in extraoral locations as well. Small intestine as a site of PBL has been described very rarely. PBL remains a diagnostic challenge given its overlapping morphologic and immunophenotypic features with other high grade lymphomas and PCM. We report a rare case of PBL of small intestine in a 48 years old HIV infected male patient. To the best of our knowledge this represents sixth case in the literature described in this location. An unusual rare pattern of CD138 positivity by IHC is also reported along with extensive review of literature of PBL in extraoral locations.

A limited plasma cell flow cytometry panel with reflex CD138 immunohistochemistry is an optimal workflow process for evaluating plasma cell neoplasms in bone marrow specimens

OBJECTIVES

To determine the optimal workflow combination of flow cytometry (FC) and immunohistochemistry tests for efficient and cost-effective evaluation of plasma cell (PC) neoplasms (PCNs) in bone marrow (BM) specimens.

METHODS

Various workflow combinations of immunohistochemistry and FC for 4,031 BM specimens worked up for PCNs were compared. Turnaround time (TAT), immunohistochemistry usage, technical charges, and addendum/amendment rates were compared between periods to determine the optimal workflow combination.

RESULTS

Five distinct workflow periods were identified, with varying combinations of full or limited FC panels for assessing PC clonality and CD138/κ/λ immunohistochemistry for PC quantification. Replacement of full FC with limited FC was associated with significant reductions in TAT and number of immunostains performed per case. Elimination of immunohistochemistry on cases determined to be polyclonal by FC also resulted in significant reductions in immunohistochemistry usage and significant cost savings.

CONCLUSIONS

Assessment of PC clonality using a limited FC panel followed by reflex CD138 immunohistochemistry on cases that are monoclonal by FC provides an optimal and cost-effective workflow for evaluating PCNs in BM samples.

Biology and bioinformatics of myeloma cell

Multiple myeloma (MM) is a plasma cell disorder that occurs in about 10% of all hematologic cancers. The majority of patients (99%) are over 50 years of age when diagnosed. In the bone marrow (BM), stromal and hematopoietic stem cells (HSCs) are responsible for the production of blood cells. Therefore any destruction or/and changes within the BM undesirably impacts a wide range of hematopoiesis, causing diseases and influencing patient survival. In order to establish an effective therapeutic strategy, recognition of the biology and evaluation of bioinformatics models for myeloma cells are necessary to assist in determining suitable methods to cure or prevent disease complications in patients. This review presents the evaluation of molecular and cellular aspects of MM such as genetic translocation, genetic analysis, cell surface marker, transcription factors, and chemokine signaling pathways. It also briefly reviews some of the mechanisms involved in MM in order to develop a better understanding for use in future studies.

Assessment of bone marrow fibrosis and angiogenesis in monitoring patients with multiple myeloma

The aim of our study was to emphasize the importance of accurate and standardized techniques for detailed monitoring of the microenvironment in multiple myeloma (MM). Bone marrow fibrosis, angiogenesis, and plasma cell infiltrates in bone marrow biopsy (BMB) samples at the time of diagnosis and on completion of therapy were analyzed for 42 patients with newly diagnosed MM. Computerized image analysis was used for all slides stained with anti-CD138 and anti-CD34. The patients with fibrosis in pretreatment BMB samples had significantly higher microvessel density (MVD) and plasma cell infiltrates. In posttreatment BMB samples, nonresponders had a significantly higher frequency and grade of fibrosis and higher values of MVD, total vascular area, and plasma cell percentage. The overall survival of nonresponders and patients with increased marrow fibrosis in posttreatment BMB samples was significantly shorter. The obtained results confirm that complex morphologic examination of the bone marrow microenvironment during the monitoring of MM can provide better prognostic significance.

Utility of a column-free cell sorting system for separation of plasma cells in multiple myeloma FISH testing in clinical laboratories

Targeted FISH analysis is an essential component of the management of plasma cell myeloma for identification of cytogenetic abnormalities. The purpose of this study was to evaluate the column-free method, RoboSep® (RS), for sorting CD138-expressing cells in bone marrow aspirates. Comparative analysis of column-based and RS methodologies was carried out on 54 paired bone marrow aspirate validation samples from patients undergoing work-up for plasma cell dyscrasia. Abnormalities detected by FISH analysis using an IGH@/CCND1 probe set were seen in 54% with RS, and 44% with column-based. We found a statistically significant difference between the yield of abnormalities detected in paired positive cases (p = 0.0001). An additional 183 consecutive post-validation samples sorted by RS showed recurrent genetic abnormalities in 85/120 (71%) of successfully sorted samples with ≥ 1% plasma cells but in none of 63 samples in which FISH analysis was completed on samples that could not be sorted due to insufficient plasma cells upon cell sorting. The column-free method successfully sorted PC, when present in ≥ 1% of cells, for detection of abnormalities by FISH. Furthermore, our data suggest that FISH analysis should not be performed on samples with an inadequate yield at the cell selection step.

Waldenström macroglobulinemia: a review of the entity and its differential diagnosis

The definition of Waldenström macroglobulinemia (WM), originally described in 1944, has been refined substantially over time. The current fourth edition of the World Health Organization of lymphoid neoplasms, in large part, adopted criteria proposed for WM at a consensus conference in 2002. WM is defined as lymphoplasmacytic lymphoma involving the bone marrow associated with a serum immunoglobulin (Ig) M paraprotein of any concentration. Morphologically, WM is composed of a variable mixture of lymphocytes, plasmacytoid lymphocytes, and plasma cells. Immunophenotypically, the neoplastic cells express monotypic IgM and light chain: B lymphocytes express pan-B-cell antigens and surface Ig are usually negative for CD5 and CD10; and plasma cells are typically positive for CD138, CD38, CD45, cytoplasmic Ig, and CD19 (in a substantial subset of cases). The putative cell of origin of WM is a postantigen selected memory B-cell that has undergone somatic hypermutation. The most common cytogenetic abnormality in WM is del(6q), usually in the region 6q23-24.3, present in 40% to 50% of cases. IGH gene translocations are rare and recurrent chromosomal translocations or gene aberrations have not been identified in WM. Here, we provide a historical perspective of WM, review clinical and pathologic aspects of the disease as it is currently defined, and discuss some practical issues in the differential diagnosis of WM that pathologists encounter in the signout of cases.

Update on the Diagnosis and Classification of the Plasma Cell Neoplasms

The plasma cell neoplasms are malignancies of the most terminally differentiated cells in B-cell ontogeny and are usually associated with the production of a monoclonal immunoglobulin molecule or M protein. These malignancies include tumors whose clinical manifestations are directly attributable to the end-organ damage induced by the dysregulated proliferation of neoplastic plasma cells. In contrast, disorders, such as primary amyloidosis, have a paradoxically low burden of neoplastic plasma cells, rendered highly pathogenic by the end-organ damage induced by deposition of the secreted paraprotein. In this article, discussion focuses on plasma cell myeloma. The molecular pathogenesis of plasma cell myeloma is reviewed and the diagnosis of the plasma cell neoplasms discussed.

Monitoring residual myeloma: high-resolution serum/urine electrophoresis or marrow biopsy with immunohistochemical analysis?

Numerous methods exist for monitoring residual disease in multiple myeloma using peripheral blood, urine, and bone marrow (BM) techniques. This study was conducted in a cohort of 83 patients to compare residual disease detection using serum protein electrophoresis (SPE) and urine protein electrophoresis (UPE) with immunofixation with immunoperoxidase staining of BM tissue sections. Of the 83 patients, 49 had a positive SPE and/or UPE result and all had BM involvement shown by immunohistochemical analysis. The results for SPE and UPE were negative in 17 patients, and all 17 had a negative immunohistochemical BM result for a negative predictive value for SPE/UPE of 100%. In addition, SPE and UPE detected residual disease in 17 patients with negative BM biopsy studies. SPE and UPE can be used to screen patients for residual disease, and negative results for both can obviate the need for BM biopsy for the detection of residual disease by immunohistochemical analysis.

Combined evaluation of bone marrow aspirate and biopsy is superior in the prognosis of multiple myeloma

Background

Estimation of plasma cell infiltrates in bone marrow aspirates (BMA) and bone marrow biopsy (BMB) is a standard method in the diagnosis and monitoring of multiple myeloma (MM). Plasma cell fraction in the bone marrow is therefore critical for the classification and optimal clinical management of patients with plasma cell dyscrasias. The aim of the study was to compare the percentage of plasma cells obtained by both methods with the patient clinical parameters and survival.

Methods

This retrospective study included BMA and BMB of 59 MM patients. The conventional differential count was determined in BMA to estimate the percentage and cytologic grade of plasma cells. The pattern of neoplastic infiltration and percentage of plasma cells were estimated on CD138 immunostained BMB slides microscopically and by computer-assisted image analysis (CIA).

Results

Significantly higher values of plasma cell infiltrates were observed in pathologist (47.7 ± 24.8) and CIA (44.1 ± 30.6) reports in comparison with cytologist analysis (30.6 ± 17.1; P < 0.001 and P < 0.0048, respectively). BMB assessment by pathologist counting and using CIA showed strongest correlation (r = 0.8; P < 0.0001). Correlation was also observed between the pathologist and cytologist counts (r = 0.321; P = 0.015) as well as comparing the percentage of plasma cells in BMA and CIA (r = 0.27; P = 0.05). Patients with clinical stage I/II had a significantly lower CIA plasma cell count than those with clinical stage III (P = 0.008). Overall survival was shorter in patients with more than 25% of atypical plasma cell morphology estimated in BMA (P = 0.05) and a higher percentage of tumor cell infiltrates estimated by the pathologist and CIA (P = 0.0341 and P = 0.013, respectively).

Conclusion

Study results suggested the combined analyses to be useful as a routine procedure to achieve more accurate and informative diagnostic data.

Metastatic hepatocellular carcinoma with CD138 positivity: an unusual mimic of multiple myeloma?

CD138 is a monoclonal anti-syndecan-1 antibody that is often used to identify plasma cells in the bone marrow of patients with multiple myeloma (MM). Several carcinomas may also express CD138 including prostate, colon, renal cell, and hepatocellular carcinoma (HCC). We report a case of metastatic HCC that presented as a soft tissue mass on the back of a 67-year-old male. Based on the clinical and radiologic findings, MM was strongly suspected. In addition, fine-needle aspiration biopsy (FNAB) of the mass revealed neoplastic cells that were positive for CD138, both by immunohistochemistry (IHC) and flow cytometry. The cytomorphologic features however did not support a diagnosis of MM, but were consistent with metastatic HCC. Our case highlights the potential problems that may arise by over-reliance on IHC and flow cytometry. Careful morphologic assessment as well as clinical and radiologic correlation are very important when evaluating any CD138-positive neoplasm. This approach should improve diagnostic accuracy and reduce the risk of erroneous interpretation of aberrant IHC results. In addition, we examined the expression of CD138 in known cases of HCC.