There are minimal criteria for the diagnosis of multiple myeloma . There must be at least 10 percent abnormal plasma cells in the bone marrow or proof of an extramedullary plasmacytoma plus the usual clinical features of multiple myeloma and at least one of the following abnormalities:
• an M-protein in the blood (usually greater than 3 gm/dL)
• an M-protein in the urine (Bence Jones protein)
• osteolytic lesions.
Connective tissue diseases (such as rheumatoid arthritis, polymyositis or cleroderma), chronic infections, metastatic cancer, lymphoma and leukemia may resemble some of the characteristics of multiple myeloma.
The diagnosis must differentiate those with true multiple myeloma from those with monoclonal gammopathy of undetermined significance (MGUS) and smoldering multiple myeloma (SMM), since people with these conditions should be observed indefinitely and not given therapy unless they develop features of multiple myeloma.
Physical Examination
• Physical findings are often general and non-specific. Pallor (paleness) is the most common physical finding.
• The liver can be felt in about one-fifth of patients; the spleen is rarely felt.
• There may be tumors outside the bone marrow (extramedullary plasmacytomas).
