General Information About Plasma Cell Neoplasms

There are several types of plasma cell neoplasms. These diseases are all associated with a monoclonal (or myeloma) protein (M protein). They include monoclonal gammopathy of undetermined significance (MGUS), isolated plasmacytoma of the bone, extramedullary plasmacytoma, and multiple myeloma.

(Refer to the Lymphoplasmacytic Lymphoma (Waldenström Macroglobulinemia) section in the PDQ summary on Adult Non-Hodgkin Lymphoma Treatment for more information.)

Incidence and Mortality

Estimated new cases and deaths from multiple myeloma in the United States in 2014:[1]

  • New cases: 24,050.
  • Deaths: 11,090.

Clinical Presentation and Evaluation

Table 1. Clinical Presentation of Plasma Cell Neoplasms

Plasma Cell Neoplasm M Protein Type Pathology Clinical Presentation
MGUS = monoclonal gammopathy of undetermined significance.
MGUS IgG kappa or lambda; or IgA kappa or lambda <10% plasma cells in bone marrow Asymptomatic, with minimal evidence of disease (aside from the presence of an M protein)[2]
Isolated plasmacytoma of bone IgG kappa or lambda; or IgA kappa or gamma Solitary lesion of bone; <10% plasma cells in marrow of uninvolved site Asymptomatic or symptomatic
Extramedullary plasmacytoma IgG kappa or lambda; or IgA kappa or gamma Solitary lesion of soft tissue; most commonly occurs in the nasopharynx, tonsils, or paranasal sinuses[3] Asymptomatic or symptomatic
Multiple myeloma IgG kappa or lambda; or IgA kappa or gamma Often, multiple lesions of bone Symptomatic

Evaluation of patients with monoclonal (or myeloma) protein (M protein)

Idiotypic myeloma cells can be found in the blood of myeloma patients in all stages of the disease.[4,5] For this reason, when treatment is indicated, systemic treatment must be considered for all patients with symptomatic plasma cell neoplasms. Patients with MGUS or asymptomatic, smoldering myeloma do not require immediate treatment but must be followed carefully for signs of disease progression.

The major challenge is to separate the stable, asymptomatic group of patients who do not require treatment from patients with progressive, symptomatic myeloma who should be treated immediately.[6,7]

Patients with a monoclonal (or myeloma) protein (M protein) in the serum and/or urine are evaluated by some of the following criteria:

  • Measure and follow the serum M protein by serum electrophoresis or by specific immunoglobulin assays; however, specific immunoglobulin quantification always overestimates the M protein because normal immunoglobulins are included in the result. For this reason, baseline and follow-up measurements of the M protein should be done by the same method.[8] Quantitative serum-free light chains may be helpful to follow response if an M protein is not apparent.
  • Measure and follow the amount of M-protein light chains excreted in the urine over 24 hours. Measure the total amount of protein excreted over 24 hours and multiply this value by the percentage of urine protein that is M protein, as determined by electrophoresis of concentrated urine protein. An easier, but less accurate, method uses a spot-urine protein electrophoresis.
  • Identify the heavy and light chain of the M protein by immunofixation electrophoresis.
  • Measure the hemoglobin, leukocyte, platelet, and differential counts.
  • Sometimes, determine the percentage of marrow plasma cells. Be aware that marrow plasma-cell distribution may vary in different sites.
  • Measure serum-free kappa and lambda light chain. This is especially useful in cases of oligosecretory plasma-cell dyscrasia or for following cases of light-chain amyloidosis.[9]
  • Take needle aspirates of a solitary lytic bone lesion, extramedullary tumor(s), or enlarged lymph node(s) to determine whether these are plasmacytomas.
  • Evaluate renal function with serum creatinine and a creatinine clearance.
  • Electrophoresis of concentrated urine protein is very helpful in differentiating glomerular lesions from tubular lesions. Glomerular lesions, such as those resulting from glomerular deposits of amyloid or light-chain deposition disease, result in the nonselective leakage of all serum proteins into the urine; the electrophoresis pattern of this urine resembles the serum pattern with a preponderance of albumin.

    In most myeloma patients, the glomeruli function normally allows only the small molecular weight proteins, such as light chains, to filter into the urine. The concentration of protein in the tubules increases as water is reabsorbed. This leads to precipitation of proteins and the formation of tubular casts, which may injure the tubular cells. With tubular lesions, the typical electrophoresis pattern shows a small albumin peak and a larger light-chain peak in the globulin region; this tubular pattern is the usual pattern found in myeloma patients.

  • Measure serum levels of calcium, alkaline phosphatase, lactic dehydrogenase, and, when indicated by clinical symptoms, cryoglobulins and serum viscosity.
  • Obtain radiographs of the skull, ribs, vertebrae, pelvis, shoulder girdle, and long bones. Whole-body, low-dose, nonenhanced, multidetector-computed tomography and magnetic resonance imaging (MRI) are being evaluated as measures for therapy response monitoring.[10,11] MRI of the spine or long bones is more sensitive in detecting lytic lesions, but any prognostic or therapeutic value for this information remains to be determined.[11]
  • Perform MRI if a paraspinal mass is detected or if symptoms suggest spinal cord or nerve root compression.
  • If amyloidosis is suspected, perform a needle aspiration of subcutaneous abdominal fat and stain the bone marrow biopsy for amyloid as the easiest and safest way to confirm the diagnosis.[12]
  • Measure serum albumin and beta-2-microglobulin as independent prognostic factors.[13,14]
  • A high plasma cell labeling index (≥3%) or the presence of circulating myeloma cells are considered poor prognostic factors.[15] Primary plasma cell leukemia has a particularly poor prognosis.[16]


These initial studies should be compared with subsequent values at a later time, when it is necessary to decide whether the disease is stable or progressive, responding to treatment, or getting worse.

As mentioned before, the major challenge is to separate the stable, asymptomatic group of patients who do not require treatment from patients with progressive, symptomatic myeloma who should be treated immediately.[6,7]

Monoclonal Gammopathy of Undetermined Significance (MGUS)

Patients with MGUS have an M protein in the serum without findings of multiple myeloma, macroglobulinemia, amyloidosis, or lymphoma and have fewer than 10% of plasma cells in the bone marrow.[2,17,18,19] Patients with smoldering myeloma have similar characteristics but may have more than 10% of plasma cells in the bone marrow.

These types of patients are asymptomatic and should not be treated. They must, however, be followed carefully since about 1% to 2% of MGUS patients per year will progress to develop myeloma (most commonly), amyloidosis, lymphoma, or chronic lymphocytic leukemia and may then require therapy.[19,20,21]

Virtually all cases of multiple myeloma are preceded by a gradually rising level of MGUS.[22,23,24]

Risk factors that predict disease progression include the following:

  • An abnormal serum-free light chain ratio.
  • Non-IgG class MGUS.
  • A high serum-M protein level (≥15 g/L).[25]

Isolated Plasmacytoma of Bone

The patient has an isolated plasmacytoma of the bone if the following are found:

  • A solitary lytic lesion of plasma cells on skeletal survey in an otherwise asymptomatic patient.
  • A bone marrow examination from an uninvolved site contains less than 10% plasma cells.[26,27,28]

When clinically indicated, MRI may reveal unsuspected bony lesions that were undetected on standard radiographs. MRI scans of the total spine may identify other bony lesions.[29]

Extramedullary Plasmacytoma

A patient has extramedullary plasmacytoma if the following are found:

  • Isolated plasma-cell tumors of soft tissues, most commonly occurring in the tonsils, nasopharynx, or paranasal sinuses.
  • Negative findings on skeletal x-rays and bone marrow biopsy.[30,31,32]

Multiple Myeloma

Multiple myeloma is a systemic malignancy of plasma cells that typically involves multiple sites within the bone marrow and secretes all or part of a monoclonal antibody.



Multiple myeloma is highly treatable but rarely curable. The median survival in the prechemotherapy era was about 7 months. After the introduction of chemotherapy, prognosis improved significantly with a median survival of 24 to 30 months and a 10-year survival rate of 3%. Even further improvements in prognosis have occurred because of the introduction of newer therapies such as pulse corticosteroids, thalidomide, lenalidomide, bortezomib, and autologous and allogeneic stem cell transplantation, with median survivals now exceeding 45 to 60 months.[33,34,35,36] Patients with plasma cell leukemia or with soft tissue plasmacytomas (often with plasmablastic morphology) in association with multiple myeloma have poor outcomes.[16,37]

Multiple myeloma is potentially curable when it presents as a solitary plasmacytoma of bone or as an extramedullary plasmacytoma. (Refer to the Isolated Plasmacytoma of Bone and Extramedullary Plasmacytoma sections of this summary for more information.)

Amyloidosis Associated With Plasma Cell Neoplasms

Multiple myeloma and other plasma cell neoplasms may cause a condition called amyloidosis. Primary amyloidosis can result in severe organ dysfunction especially in the kidney, heart, or peripheral nerves. Clinical symptoms and signs include the following:

Elevated serum levels of cardiac troponins, amino-terminal fragment brain-type natriuretic peptide, and serum-free light chains are poor prognostic factors.[38,39] A proposed staging system for primary systemic amyloidosis based on these serum levels requires independent and prospective confirmation.[38]


  1. American Cancer Society: Cancer Facts and Figures 2014. Atlanta, Ga: American Cancer Society, 2014. Available online. Last accessed May 21, 2014.
  2. Kyle RA, Rajkumar SV: Monoclonal gammopathy of undetermined significance and smouldering multiple myeloma: emphasis on risk factors for progression. Br J Haematol 139 (5): 730-43, 2007.
  3. Knowling MA, Harwood AR, Bergsagel DE: Comparison of extramedullary plasmacytomas with solitary and multiple plasma cell tumors of bone. J Clin Oncol 1 (4): 255-62, 1983.
  4. Zandecki M, Facon T, Preudhomme C, et al.: Significance of circulating plasma cells in multiple myeloma. Leuk Lymphoma 14 (5-6): 491-6, 1994.
  5. Billadeau D, Van Ness B, Kimlinger T, et al.: Clonal circulating cells are common in plasma cell proliferative disorders: a comparison of monoclonal gammopathy of undetermined significance, smoldering multiple myeloma, and active myeloma. Blood 88 (1): 289-96, 1996.
  6. He Y, Wheatley K, Clark O, et al.: Early versus deferred treatment for early stage multiple myeloma. Cochrane Database Syst Rev (1): CD004023, 2003.
  7. Kyle RA, Remstein ED, Therneau TM, et al.: Clinical course and prognosis of smoldering (asymptomatic) multiple myeloma. N Engl J Med 356 (25): 2582-90, 2007.
  8. Riches PG, Sheldon J, Smith AM, et al.: Overestimation of monoclonal immunoglobulin by immunochemical methods. Ann Clin Biochem 28 ( Pt 3): 253-9, 1991.
  9. Dispenzieri A, Kyle R, Merlini G, et al.: International Myeloma Working Group guidelines for serum-free light chain analysis in multiple myeloma and related disorders. Leukemia 23 (2): 215-24, 2009.
  10. Horger M, Kanz L, Denecke B, et al.: The benefit of using whole-body, low-dose, nonenhanced, multidetector computed tomography for follow-up and therapy response monitoring in patients with multiple myeloma. Cancer 109 (8): 1617-26, 2007.
  11. Walker R, Barlogie B, Haessler J, et al.: Magnetic resonance imaging in multiple myeloma: diagnostic and clinical implications. J Clin Oncol 25 (9): 1121-8, 2007.
  12. Gertz MA, Li CY, Shirahama T, et al.: Utility of subcutaneous fat aspiration for the diagnosis of systemic amyloidosis (immunoglobulin light chain). Arch Intern Med 148 (4): 929-33, 1988.
  13. Greipp PR: Advances in the diagnosis and management of myeloma. Semin Hematol 29 (3 Suppl 2): 24-45, 1992.
  14. Durie BG, Stock-Novack D, Salmon SE, et al.: Prognostic value of pretreatment serum beta 2 microglobulin in myeloma: a Southwest Oncology Group Study. Blood 75 (4): 823-30, 1990.
  15. Greipp PR, Witzig T: Biology and treatment of myeloma. Curr Opin Oncol 8 (1): 20-7, 1996.
  16. Pagano L, Valentini CG, De Stefano V, et al.: Primary plasma cell leukemia: a retrospective multicenter study of 73 patients. Ann Oncol 22 (7): 1628-35, 2011.
  17. Kyle RA, Therneau TM, Rajkumar SV, et al.: Prevalence of monoclonal gammopathy of undetermined significance. N Engl J Med 354 (13): 1362-9, 2006.
  18. International Myeloma Working Group: Criteria for the classification of monoclonal gammopathies, multiple myeloma and related disorders: a report of the International Myeloma Working Group. Br J Haematol 121 (5): 749-57, 2003.
  19. Bird J, Behrens J, Westin J, et al.: UK Myeloma Forum (UKMF) and Nordic Myeloma Study Group (NMSG): guidelines for the investigation of newly detected M-proteins and the management of monoclonal gammopathy of undetermined significance (MGUS). Br J Haematol 147 (1): 22-42, 2009.
  20. Attal M, Harousseau JL, Stoppa AM, et al.: A prospective, randomized trial of autologous bone marrow transplantation and chemotherapy in multiple myeloma. Intergroupe Français du Myélome. N Engl J Med 335 (2): 91-7, 1996.
  21. Kyle RA, Therneau TM, Rajkumar SV, et al.: A long-term study of prognosis in monoclonal gammopathy of undetermined significance. N Engl J Med 346 (8): 564-9, 2002.
  22. Weiss BM, Abadie J, Verma P, et al.: A monoclonal gammopathy precedes multiple myeloma in most patients. Blood 113 (22): 5418-22, 2009.
  23. Landgren O, Kyle RA, Pfeiffer RM, et al.: Monoclonal gammopathy of undetermined significance (MGUS) consistently precedes multiple myeloma: a prospective study. Blood 113 (22): 5412-7, 2009.
  24. Bladé J, Rosiñol L, Cibeira MT: Are all myelomas preceded by MGUS? Blood 113 (22): 5370, 2009.
  25. Rajkumar SV, Kyle RA, Therneau TM, et al.: Serum free light chain ratio is an independent risk factor for progression in monoclonal gammopathy of undetermined significance. Blood 106 (3): 812-7, 2005.
  26. Ozsahin M, Tsang RW, Poortmans P, et al.: Outcomes and patterns of failure in solitary plasmacytoma: a multicenter Rare Cancer Network study of 258 patients. Int J Radiat Oncol Biol Phys 64 (1): 210-7, 2006.
  27. Dimopoulos MA, Moulopoulos LA, Maniatis A, et al.: Solitary plasmacytoma of bone and asymptomatic multiple myeloma. Blood 96 (6): 2037-44, 2000.
  28. Dimopoulos MA, Hamilos G: Solitary bone plasmacytoma and extramedullary plasmacytoma. Curr Treat Options Oncol 3 (3): 255-9, 2002.
  29. Liebross RH, Ha CS, Cox JD, et al.: Solitary bone plasmacytoma: outcome and prognostic factors following radiotherapy. Int J Radiat Oncol Biol Phys 41 (5): 1063-7, 1998.
  30. Tournier-Rangeard L, Lapeyre M, Graff-Caillaud P, et al.: Radiotherapy for solitary extramedullary plasmacytoma in the head-and-neck region: A dose greater than 45 Gy to the target volume improves the local control. Int J Radiat Oncol Biol Phys 64 (4): 1013-7, 2006.
  31. Michalaki VJ, Hall J, Henk JM, et al.: Definitive radiotherapy for extramedullary plasmacytomas of the head and neck. Br J Radiol 76 (910): 738-41, 2003.
  32. Alexiou C, Kau RJ, Dietzfelbinger H, et al.: Extramedullary plasmacytoma: tumor occurrence and therapeutic concepts. Cancer 85 (11): 2305-14, 1999.
  33. Kumar SK, Rajkumar SV, Dispenzieri A, et al.: Improved survival in multiple myeloma and the impact of novel therapies. Blood 111 (5): 2516-20, 2008.
  34. Ludwig H, Durie BG, Bolejack V, et al.: Myeloma in patients younger than age 50 years presents with more favorable features and shows better survival: an analysis of 10 549 patients from the International Myeloma Working Group. Blood 111 (8): 4039-47, 2008.
  35. Brenner H, Gondos A, Pulte D: Recent major improvement in long-term survival of younger patients with multiple myeloma. Blood 111 (5): 2521-6, 2008.
  36. Palumbo A, Anderson K: Multiple myeloma. N Engl J Med 364 (11): 1046-60, 2011.
  37. Bladé J, Fernández de Larrea C, Rosiñol L, et al.: Soft-tissue plasmacytomas in multiple myeloma: incidence, mechanisms of extramedullary spread, and treatment approach. J Clin Oncol 29 (28): 3805-12, 2011.
  38. Kumar S, Dispenzieri A, Lacy MQ, et al.: Revised prognostic staging system for light chain amyloidosis incorporating cardiac biomarkers and serum free light chain measurements. J Clin Oncol 30 (9): 989-95, 2012.
  39. Pinney JH, Lachmann HJ, Bansi L, et al.: Outcome in renal Al amyloidosis after chemotherapy. J Clin Oncol 29 (6): 674-81, 2011.
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