MM: multiple myeloma; AL: amyloid light-chain; MGUS: monoclonal gammopathy of undetermined significance; SPEP: serum protein electrophoresis; FLC: free light chain; IgG: immunoglobulin G; FISH: fluorescence in situ hybridization; LDH: lactate dehydrogenase; CRAB: hypercalcemia, renal insufficiency, anemia, bone lesions; IgA: immunoglobulin A; IgD: immunoglobulin D; IgM: immunoglobulin M; CT: computed tomography; MRI: magnetic resonance imaging; PET: positron emission tomography; SLiM: ≥60% clonal plasma cells in the bone marrow; involved/uninvolved FLC ratio of 100 or more (provided involved FLC level is at least 100 mg/L); MRI with more than one focal lesion (involving bone or bone marrow).
* Patients with solitary plasmacytoma, non-secretory multiple myeloma, and rare cases of AL amyloidosis may not have detectable M protein or abnormal serum FLC assay.
¶ Imaging should be performed using whole body low dose CT, whole body PET/CT, whole body MRI, or MRI of the spine and pelvis (depending upon availability and institutional preference). Biopsy of the bone lesion should be performed if a solitary lesion is detected or if the cause of the lesion is unclear. Bone imaging may be omitted for patients with IgM M protein and no clinical concern for bone lesions or myeloma.