Multiple myeloma
(Plasma cell myeloma, medullary plasmacytoma)

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Based on the current guidelines and the current state of research, there are different diagnostic recommendations for patients with multiple myeloma. We have summarized the most important information on the classification and diagnostic methods at MLL. In addition, we have compiled further links on prognosis and therapy in multiple myeloma, so that you can inform yourself in more detail.

Method:
Anticoagulant:
Recommendation:

Method:

Cytomorphology
Anticoagulant:

EDTA
Recommendation:

obligatory

Method:

Immunophenotyping
Anticoagulant:

EDTA or Heparin
Recommendation:

facultative

Method:

Chromosome analysis
Anticoagulant:
Recommendation:

no

Method:

FISH
Anticoagulant:

EDTA or Heparin
Recommendation:

obligatory*

Method:

Molecular genetics
Anticoagulant:

EDTA
Recommendation:

obligatory*

* after CD138+ sorting

Classification
Diagnostics
Prognosis
Therapy
Recommendation

Multiple myeloma: Classification and staging

According to the 2022 WHO-classification, multiple myeloma belongs to the group of plasma cell neoplasms within mature B-cell neoplasms (WHO 2022).

The International Staging System (ISS, 2005 – ISS-Score) and the Revised ISS (R-ISS, 2015 – R-ISS-Score; R2-ISS, 2022) of the International Myeloma Working Group IMWG are used for staging. In addition to serum parameters, the R-ISS/R2-ISS also includes cytogenetic risk factors (see below).

Multiple Myeloma: Diagnostic methods and their relevance

Important for differentiating multiple myeloma, monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM)

Cytomorphologic examination of bone marrow aspirates or biopsies is performed as standard procedure to assess plasma cell (PC) numbers and atypia. In combination with immunophenotyping or pathology, this is primarily used to differentiate multiple myeloma (>10% clonal PC) from MGUS (<10% clonal PC).

CD45, CD19, CD56 and CD138 are relevant surface markers in multiple myeloma

Malignant plasma cells often show decreased or absent expression of the pan-leukocyte antigen CD45 and the B-cell marker CD19 compared to healthy, polyclonal plasma cells. In addition, aberrant expression of the antigen CD56, which is normally not expressed relevantly on plasma cells, is apparent in many cases. In some cases, there is loss of expression of CD27 and/or CD81. In about one third of cases, aberrant expression of CD20, CD28, CD33 and CD117 can be detected (WHO 2022).

Determination of measurable/minimal residual disease (MRD)

Immunophenotyping is also useful for follow-up diagnosis after therapy of multiple myeloma and established for the determination of measurable residual disease (MRD). Meta-analyses have confirmed the high prognostic value of MRD negativity (Landgren et al. 2016, Lahuerta et al. 2017, Munshi et al. 2017, Munshi et al. 2020). It is already used as an endpoint in many studies (Mateos et al. 2018, Avet-Loiseau et al. 2020, Anderson et al. 2021, Bertamini et al. 2021).

In classical chromosome analysis, aberrant plasma cells are usually not detected due to low proliferation activity in vitro. Instead, FISH analysis on interphase nuclei is the gold standard in multiple myeloma.

FISH analysis has a special value in multiple myeloma. After enrichment by magnetic activated cell sorting (MACS) for CD138+ cells, a plasma cell purity level of mostly > 80% is achieved even in MGUS, even if the infiltration level in native bone marrow is much lower. Due to the enrichment of CD138+ cells, chromosomal alterations can be detected by FISH in 88-97% of all multiple myelomas, some with great prognostic relevance.

For cytogenetic diagnostics, the International Myeloma Working Group, the European Myeloma Network, and the Cancer Genomics Consortium Plasma Cell Neoplasm Working Group (Lu et al. 2025) recommend performing FISH analyses to detect 17p deletion, 1p deletions, and 1q gains, as well as t(4;14) , t(14;16), t(14;20), and, if applicable, t(11;14) (Caers et al. 2018, Avet-Loiseau et al. 2025, Lu et al. 2025). See Table 1 for markers relevant to risk stratification.

Table 1: Cytogenetic high-risk factors

Publication	High-risk marker
Cytogenetic (after Palumbo et al. 2015)	t(4;14), t(14;16), del(17p)
Cytogenetic (after Sonneveld et al. 2016)	t(4;14), t(14;16), del(17p), t(14;20), 1q gain(s)
Cytogenetic (after Ravi & Gonsalves 2021)	t(4;14), t(14;16), del(17p), t(14;20), 1q gain(s), del(1p), MYC-Rearrangement
(D'Agostino et al. 2022)	t(4;14), del(17p), 1q gain(s)
(Avet-Loiseau et al. 2025)	del(17p) (≥ 20% of selected plasma cells) 1q gain(s) together with t(4;14)/ t(14;16)/t(14;20) or monoallelic del(1p32) biallelic del(1p32)*

*Detection and, if necessary, analysis using NGS-based methods may be required

Differentiation of hyperdiploid and non-hyperdiploid multiple myeloma

Cytogenetically, the hyperdiploid group can be classically distinguished from the non-hyperdiploid group (Sawyer 2011):

Cytogenetic classification of multiple myeloma (International Myeloma Working Group, IMWG):

hyperdiploid MM: 50-60% of patients, multiple trisomies, favorable prognosis

non-hyperdiploid MM: 40-50% of patients, hypodiploid/pseudodiploid chromosome sets, high incidence of IGH translocations, prognosis dependent on specific IGH rearrangement (see Table 1).

Basic diagnostic Panel:

BRAF, KRAS, NRAS, TP53

The identification of mutations in the TP53 gene, which represent a high-risk genetic marker, is of great prognostic significance (Avet-Loiseau et al. 2025) and should therefore be investigated as mandatory (Onkopedia guideline on multiple myeloma). If a TP53 mutation is present in addition to del(17p), resulting in biallelic TP53 inactivation, this leads to an extremely unfavorable prognosis (Walker et al. 2019, Corre et al. 2021).

Beyond the TP53 mutation, mutations in the RAS genes, KRAS and NRAS, are also considered secondary genetic aberrations, with incidences of 20% each. Due to the high incidences of RAS mutations and the availability of pathway-inhibitors, these aberrations represent an interesting future therapeutic option. Accordingly, inhibitors are already being tested in preclinical and clinical studies successfully (Walker et al. 2015, Heuck et al. 2016, Sriskandarajah et al. 2020, Lu et al. 2024).

Another potential target of targeted therapies is the hotspot mutation V600E in the BRAF gene (Andrulis et al. 2013, Robiou du Pont et al. 2017).

Multiple Myeloma: Prognosis

The prognosis for patients with multiple myeloma varies considerably and is influenced by several genetic and chromosomal abnormalities. The prognostic factors mentioned so far (ISS/R-ISS, cytogenetics) have been validated mainly in the context of newly diagnosed MM, and their prognostic significance is largely maintained during the course of therapy and disease (Pawlyn & Davies 2019). In addition, other factors include MRD negativity and duration of relapse-free survival.

Identifying high-risk factors is crucial for risk stratification and developing a tailored treatment plan. The International Myeloma Society/International Myeloma Working Group (IMS-IMWG) has developed a consensus definition for high-risk MM (HRMM) to identify patients who are at increased risk of aggressive disease progression and shorter overall survival (Avet-Loiseau et al. 2025). The following criteria are considered high-risk factors:

• del(17p) (clonal fraction ≥20% of selected CD138-positive cells)

• TP53 mutation (analyzed using an NGS-based method)

• Translocation t(4;14), t(14;16) or t(14;20) together with +1q and/or del (1p32)

• monoallelic del(1p32) together with +1q

• biallelic del(1p32) (analyzed using NGS-based method)

• high β2-microglobulin (>5.5 mg/dL) with normal creatinine (<1.2 mg/dL)

Multiple Myeloma (MM): Prognosis calculation

Click here to access the prognosis calculation of the ISS score and the R-ISS score. In addition, the forecast calculation can be performed according to R2-ISS. The risk of progression from MGUS to myeloma or lymphoproliferative disease can be estimated using the MGUS-Prognosis-Score.

Multiple Myeloma: Therapy

Guidelines on therapy can be found from Rajkumar (Rajkumar 2024), Lin et al. (Lin et al. 2024), Dimopoulos et al. (EHA-ESMO Guidelines, Dimopoulos et al. 2021), from the National Comprehensive Cancer Network (NCCN) (Kumar et al. 2023), and on the Onkopedia website (Onkopedia Guideline Multiple Myeloma), among others.

Recommendation

Due to artifacts, dilution by peripheral blood or focally different infiltration, cytomorphological and flow cytometric assessment of bone marrow aspirates may underestimate the true plasma cell infiltration. Therefore, according to recommendations of the European Myeloma Network (EMN), an additional bone marrow biopsy should be performed (Caers et al. 2018). If there are discrepancies in the determination of plasma cell infiltration on biopsy and aspirate, the IMWG consensus is that the higher of the two values should be used (Rajkumar et al. 2014).

Status: September 2025

Anderson KC et al. Minimal Residual Disease in Myeloma: Application for Clinical Care and New Drug Registration. Clin Cancer Res 2021;27(19):5195-5212.

Andrulis M et al. Targeting the BRAF V600E mutation in multiple myeloma. Cancer Discov 2013;3(8):862-869.

Avet-Loiseau H et al. International Myeloma Society/International Myeloma Working Group Consensus Recommendations on the Definition of High-Risk Multiple Myeloma. J Clin Oncol 2025;Jco2401893.

Avet-Loiseau H et al. Minimal Residual Disease Status as a Surrogate Endpoint for Progression-free Survival in Newly Diagnosed Multiple Myeloma Studies: A Meta-analysis. Clin Lymphoma Myeloma Leuk 2020;20(1):e30-e37.

Bertamini L et al. MRD Assessment in Multiple Myeloma: Progress and Challenges. Curr Hematol Malig Rep 2021;16(2):162-171.

Caers J et al. European Myeloma Network recommendations on tools for the diagnosis and monitoring of multiple myeloma: what to use and when. Haematologica 2018;103(11):1772-1784.

Corre J et al. del(17p) without TP53 mutation confers a poor prognosis in intensively treated newly diagnosed patients with multiple myeloma. Blood 2021;137(9):1192-1195.

D'Agostino M et al. Second Revision of the International Staging System (R2-ISS) for Overall Survival in Multiple Myeloma: A European Myeloma Network (EMN) Report Within the HARMONY Project. J Clin Oncol 2022;40(29):3406-3418.

Dimopoulos MA et al. Multiple myeloma: EHA-ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up(dagger). Ann Oncol 2021;32(3):309-322.

Heuck CJ et al. Inhibiting MEK in MAPK pathway-activated myeloma. Leukemia 2016;30(4):976-980.

Kumar SK et al. Multiple Myeloma, Version 2.2024, NCCN Clinical Practice Guidelines in Oncology. J Natl Compr Canc Netw 2023;21(12):1281-1301.

Lahuerta JJ et al. Depth of Response in Multiple Myeloma: A Pooled Analysis of Three PETHEMA/GEM Clinical Trials. J Clin Oncol 2017;35(25):2900-2910.

Landgren O et al. Role of MRD status in relation to clinical outcomes in newly diagnosed multiple myeloma patients: a meta-analysis. Bone Marrow Transplant 2016;51(12):1565-1568.

Lin CH et al. Current Novel Targeted Therapeutic Strategies in Multiple Myeloma. Int J Mol Sci 2024;25(11).

Lu Q et al. Multiple myeloma: signaling pathways and targeted therapy. Mol Biomed 2024;5(1):25.

Lu X et al. Guidelines for the testing and reporting of cytogenetic results for risk stratification of multiple myeloma: a report of the Cancer Genomics Consortium Plasma Cell Neoplasm Working Group. Blood Cancer J 2025;15(1):86.

Mateos MV et al. Daratumumab plus Bortezomib, Melphalan, and Prednisone for Untreated Myeloma. N Engl J Med 2018;378(6):518-528.

Munshi NC et al. A large meta-analysis establishes the role of MRD negativity in long-term survival outcomes in patients with multiple myeloma. Blood Adv 2020;4(23):5988-5999.

Munshi NC et al. Association of Minimal Residual Disease With Superior Survival Outcomes in Patients With Multiple Myeloma: A Meta-analysis. JAMA Oncol 2017;3(1):28-35.

Onkopedia Leitlinie „Multiples Myelom“ 2024; DGHO 2024.

Palumbo A et al. Revised International Staging System for Multiple Myeloma: A Report From International Myeloma Working Group. J Clin Oncol 2015;33(26):2863-2869.

Pawlyn C, Davies FE. Toward personalized treatment in multiple myeloma based on molecular characteristics. Blood 2019;133(7):660-675.

Rajkumar SV. Multiple myeloma: 2024 update on diagnosis, risk-stratification, and management. Am J Hematol 2024;99(9):1802-1824.

Rajkumar SV et al. International Myeloma Working Group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol 2014;15(12):e538-e548.

Ravi G, Gonsalves WI. Current diagnosis, risk stratification and treatment paradigms in newly diagnosed multiple myeloma. Cancer Treat Res Commun 2021;29(100444.

Robiou du Pont S et al. Genomics of Multiple Myeloma. J Clin Oncol 2017;35(9):963-967.

Sawyer JR. The prognostic significance of cytogenetics and molecular profiling in multiple myeloma. Cancer Genet 2011;204(1):3-12.

Sonneveld P et al. Treatment of multiple myeloma with high-risk cytogenetics: a consensus of the International Myeloma Working Group. Blood 2016;127(24):2955-2962.

Sriskandarajah P et al. Combined targeting of MEK and the glucocorticoid receptor for the treatment of RAS-mutant multiple myeloma. BMC Cancer 2020;20(1):269.

Walker BA et al. Mutational Spectrum, Copy Number Changes, and Outcome: Results of a Sequencing Study of Patients With Newly Diagnosed Myeloma. J Clin Oncol 2015;33(33):3911-3920.

Walker BA et al. A high-risk, Double-Hit, group of newly diagnosed myeloma identified by genomic analysis. Leukemia 2019;33(1):159-170.

WHO Classification of Tumours Editorial Board. Haematolymphoid tumours [Internet]. Lyon (France): International Agency for Research on Cancer; 2022. (WHO classification of tumours series, 5th ed.; vol. 11). Available from: https://tumourclassification.iarc.who.int/chapters/63.

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Multiple myeloma (Plasma cell myeloma, medullary plasmacytoma)

Multiple myeloma: Classification and staging

Multiple Myeloma: Diagnostic methods and their relevance

Cytomorphology

Immunophenotyping

Chromosome analysis

Fluorescence in situ hybridisation (FISH)

Table 1: Cytogenetic high-risk factors

Molecular genetics

Multiple Myeloma: Prognosis

Multiple Myeloma (MM): Prognosis calculation

Multiple Myeloma: Therapy

Recommendation

You may also be interested in

Multiple myeloma
(Plasma cell myeloma, medullary plasmacytoma)