Disorder	Disease definition
Non-IgM MGUS	All criteria must be met:
	(1) Serum monoclonal protein (non-IgM type) < 3 g per dL
	(2) Clonal bone marrow plasma cells < 10%
	(3) No evidence of other B-cell proliferative disorders
	(4) Absence of myeloma-related organ or tissue impairment* or CRAB criteria that can be attributed to a plasma cell proliferative disorder
IgM MGUS	All criteria must be met:
	(1) Serum monoclonal protein (IgM) < 3 g per dL
	(2) Bone marrow lymphoplasmacytic infiltration < 10%
	(3) No evidence of other B-cell proliferative disorders
	(4) Absence of constitutional symptoms, lymphadenopathy, hepatosplenomegaly, anemia, or hyperviscosity that can be attributed to a plasma cell proliferative disorder
Light chain MGUS	All criteria must be met:
	(1) Abnormal free light chain ratio (< 0.26 or > 1.65)
	(2) Increased level of the appropriate involved light chain (increased kappa free light chain in patients with ratio > 1.65 and increased lambda free light chain in patients with ratio < 0.26)
	(3) No immunoglobulin heavy chain expression on immunofixation
	(4) Absence of myeloma-related organ or tissue impairment* or CRAB criteria that can be attributed to a plasma cell proliferative disorder
	(5) Urinary monoclonal protein < 500 mg per 24 hours
Smoldering multiple myeloma	Both criteria must be met:
	(1) Serum monoclonal protein ≥ 3 g per dL, or urinary monoclonal protein ≥ 500 mg per 24 hours, and/or clonal bone marrow plasma cells 10% to 60%
	(2) Absence of myeloma-defining events or amyloidosis
Multiple myeloma	Both criteria must be met:
	(1) Clonal bone marrow plasma cells ≥ 10% or biopsy-proven bony or extramedullary plasmacytoma
	(2) Any one or more of the following myeloma-defining events:
	Evidence of end-organ damage that can be attributed to the underlying plasma cell proliferative disorder, specifically:
		Hypercalcemia: serum calcium > 1 mg per dL (0.25 mmol per L) higher than the upper limit of normal or > 11 mg per dL (> 2.75 mmol per L)
		Renal insufficiency: creatinine clearance < 40 mL per minute per 1.73 m2 (0.67 mL per second per m2) or serum creatinine > 2 mg per dL (177 μmol per L)
		Anemia: hemoglobin > 2 g per dL (20 g per L) below the lower limit of normal, or a hemoglobin value < 10 g per dL (100 g per L)
		Bone lesions: one or more osteolytic lesions on skeletal radiography, CT, or positron emission tomography/CT
	Clonal bone marrow plasma cells ≥ 60%
	Involved: uninvolved serum free light chain ratio ≥ 100 (involved free light chain level must be ≥ 100 mg per L)
	More than one focal lesion on MRI studies (≥ 5 mm size)
Solitary plasmacytoma	All criteria must be met:
	(1) Biopsy-proven solitary lesion of bone or soft tissue with evidence of clonal plasma cells
	(2) Normal bone marrow with no evidence of clonal plasma cells
	(3) Normal skeletal survey and MRI or CT of spine and pelvis except for the primary solitary lesion
	(4) Absence of myeloma-related organ or tissue impairment* or CRAB criteria that can be attributed to a lymphoplasma cell proliferative disorder
Solitary plasmacytoma with minimal marrow involvement	All criteria must be met:
	(1) Biopsy-proven solitary lesion of bone or soft tissue with evidence of clonal plasma cells
	(2) Clonal bone marrow plasma cells < 10%
	(3) Normal skeletal survey and MRI or CT of spine and pelvis except for the primary solitary lesion
	(4) Absence of myeloma-related organ or tissue impairment* or CRAB criteria that can be attributed to a lymphoplasma cell proliferative disorder
Plasma cell leukemia	Peripheral blood circulating clonal plasma cells > 2,000 per μL (2.0 × 109 per L) or 20% of leukocytes defines plasma cell leukemia
	Presence of serum monoclonal protein, bone marrow infiltration, or myeloma-related organ or tissue impairment* or CRAB criteria supports, but is not required for, diagnosis
Waldenström macroglobulinemia	Both criteria must be met:
	(1) IgM monoclonal gammopathy (IgM myeloma rare)
	(2) Bone marrow lymphoplasmacytic infiltration ≥ 10%
	Other possible findings:
	(1) Lymphoplasmacytic infiltrate expresses typical immunophenotype
	(2) Anemia, hepatosplenomegaly, and systemic symptoms typically present
Amyloid light chain (primary) amyloidosis	All criteria must be met:
	(1) Presence of an amyloid-related systemic syndrome (e.g., renal, liver, heart, gastrointestinal tract, or peripheral nerve involvement) that can be attributed to a plasma cell proliferative disorder
	(2) Positive amyloid staining by Congo red in any tissue (e.g., fat aspirate, bone marrow, organ biopsy) or the presence of amyloid fibrils on electron microscopy
	(3) Evidence that the amyloid is light chain related, established by direct examination of the amyloid using spectrometry-based proteomic analysis or immunoelectron microscopy
	(4) Evidence of a monoclonal plasma cell proliferative disorder (e.g., presence of a serum or urinary monoclonal protein, abnormal serum free light chain ratio, or clonal bone marrow plasma cells)
POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, M protein, skin changes)	Both criteria must be met:
	(1) Polyneuropathy
	(2) Monoclonal plasma cell proliferative disorder
	Plus at least one major criterion:
	(1) Osteosclerotic or mixed sclerotic/lytic lesion measuring ≥ 0.8 cm in the longest dimension
	(2) Castleman disease (giant lymph node hyperplasia, angiofollicular lymph node hyperplasia)
	(3) Elevated serum vascular endothelial growth factor levels at least three to four times the upper limit of normal
	Plus at least one minor criterion:
	(1) Organomegaly (splenomegaly, hepatomegaly, or lymphadenopathy)
	(2) Extravascular volume overload (peripheral edema, ascites, or pleural effusion)
	(3) Endocrinopathy (excluding diabetes mellitus or hypothyroidism)
	(4) Skin changes (hyperpigmentation, hypertrichosis, acrocyanosis, plethora, hemangioma, telangiectasia)
	(5) Papilledema
	(6) Thrombocytosis or polycythemia