Smouldering myeloma is a disease classified as intermediate in a spectrum of step-wise progressive diseases termed

plasma cell dyscrasia Plasma cell dyscrasias (also termed plasma cell disorders and plasma cell proliferative diseases) are a spectrum of progressively more severe monoclonal gammopathies in which a clone or multiple clones of pre-malignant or malignant plasma cells ( ...

s. In this spectrum of diseases, a clone of plasma cells secreting monoclonal

paraprotein A myeloma protein is an abnormal antibody (immunoglobulin) or (more often) a fragment thereof, such as an immunoglobulin light chain, that is produced in excess by an abnormal monoclonal proliferation of plasma cells, typically in multiple myelo ...

(also termed

myeloma protein A myeloma protein is an abnormal antibody (immunoglobulin) or (more often) a fragment thereof, such as an immunoglobulin light chain, that is produced in excess by an abnormal monoclonal proliferation of plasma cells, typically in multiple myelom ...

or M protein) causes the relatively benign disease of

monoclonal gammopathy of undetermined significance Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell dyscrasia in which plasma cells or other types of antibody-producing cells secrete a myeloma protein, i.e. an abnormal antibody, into the blood; this abnormal protein is ...

. This clone proliferates and may slowly evolve into more aggressive sub-clones that cause smouldering multiple myeloma. Further and more rapid evolution causes the overtly malignant stage of

multiple myeloma Multiple myeloma (MM), also known as plasma cell myeloma and simply myeloma, is a cancer of plasma cells, a type of white blood cell that normally produces antibodies. Often, no symptoms are noticed initially. As it progresses, bone pain, ...

and can subsequently lead to the extremely malignant stage of secondary

plasma cell leukemia Plasma cell leukemia (PCL) is a plasma cell dyscrasia, i.e. a disease involving the malignant degeneration of a subtype of white blood cells called plasma cells. It is the terminal stage and most aggressive form of these dyscrasias, constituting 2 ...

. Thus, some patients with smouldering myeloma progress to multiple myeloma and plasma cell leukemia. Smouldering myeloma, however, is not a malignant disease. It is characterised as a

pre-malignant A precancerous condition is a condition, tumor or lesion involving abnormal cells which are associated with an increased risk of developing into cancer. Clinically, precancerous conditions encompass a variety of abnormal tissues with an increase ...

disease that lacks symptoms but is associated with bone marrow biopsy showing the presence of an abnormal number of clonal myeloma cells, blood and/or urine containing a myeloma protein, and a significant risk of developing into a malignant disease.

Diagnosis

Smouldering myeloma is characterised by: * Serum paraprotein >30 g/L or urinary monoclonal protein ≥500 mg per 24 h AND/OR * Clonal plasma cells >10% and <60% on bone marrow biopsy AND * ''No'' evidence of end organ damage that can be attributed to plasma cell disorder AND * ''No'' myeloma-defining event (>60% plasma cells in bone marrow OR Involved/Uninvolved light chain ratio>100)

Treatment

Treatment for multiple myeloma is focused on therapies that decrease the clonal plasma cell population and consequently decrease the signs and symptoms of disease. If the disease is completely asymptomatic (i.e. there is a paraprotein and an abnormal bone marrow population but no end-organ damage), as in smouldering myeloma, treatment is typically deferred, or restricted to clinical trials. They are generally responsive to

IL-1β Interleukin-1 beta (IL-1β) also known as leukocytic pyrogen, leukocytic endogenous mediator, mononuclear cell factor, lymphocyte activating factor and other names, is a cytokine protein that in humans is encoded by the ''IL1B'' gene."Catabolin ...

neutralisation.

Prognosis

Smouldering myeloma with an increasingly abnormal serum free light chain (FLC) ratio is associated with a higher risk for progression to active multiple myeloma.

Diagnosis

Treatment

Prognosis

References

Further reading