Differential diagnosis
Myeloma belongs to a spectrum of closely related plasma cell disorders that are characterised by abnormal plasma cell growth in association with the presence of a serum or urine paraprotein and/or excessive free light chain production.
These can range from benign conditions such as monoclonal gammopathy of undetermined significance (MGUS) and smouldering myeloma to more active conditions such as symptomatic myeloma, plasmacytoma, AL amyloidosis, Waldenstrom’s macroglobulinaemia (WM) and plasma cell leukaemia (PCL).
The spectrum of MGUS, plasmacytoma, smouldering myeloma and myeloma is considered to represent a natural progression of the same disease. It is important, therefore to establish the correct diagnosis by distinguishing MGUS and smouldering myeloma from myeloma (and from other plasma cell disorders). This is because myeloma requires treatment whereas MGUS and smouldering myeloma in general do not require anti-myeloma treatment but are carefully and closely monitored. The updated 2014 International Myeloma Working Group diagnostic criteria, described earlier, should be used to determine a differential diagnosis of myeloma. Read more about the diagnosis of precursor conditions and other plasma cell disorders in Module 3.
Other plasma cell disorders may present with symptoms and/or laboratory features similar to those of myeloma and are therefore considered in the differential diagnosis of patients with symptoms or signs of myeloma.