The Genetic Architecture of Multiple Myeloma

Table 1

Diagnostic criteria for myeloma of undetermined significance (MGUS), smouldering multiple myeloma (SMM), myeloma, and plasma cell leukemia (PCL). Reproduced from international myeloma working group, 2003 [37].

MGUS	SMM	Myeloma	PCL
Serum M-protein <30 g/L	Serum M-protein ≥30 g/L AND/OR Bone marrow clonal plasma cells ≥10%	M-protein in serum and/or urine.* No specific concentration required	Presence of ≥20% circulating plasma cells Absolute level of >2.0 × 10^9/L
Bone marrow clonal plasma cells <10%. If done—low level of plasma cell infiltration in a trephine biopsy		Confirmed clonal plasma cells in bone marrow
Absence of end-organ disease and symptoms	Absence of end-organ disease and symptoms	Presence of myeloma-related organ or tissue impairment (ROTI)**

∗1-2% of patients have no detectable M-protein in serum or urine but do have myeloma-related organ or tissue impairment (ROTI) and increased intramedullary plasma cells; this is termed nonsecretory myeloma. **ROTI: corrected serum calcium >0.25 mmol/L above the upper limit of normal or >2.75 mmol/L, creatinine >173 mmol/L, Hb 2 g/dL below the lower limit of normal or <10 g/dL, lytic bone lesions or osteoporosis with compression fractures (may be clarified by CT or MRI), symptomatic hyperviscosity, amyloidosis, recurrent bacterial infections (>2 episodes in 12 months).