Plasma Cell Myeloma
Definition
- Multifocal clonal proliferation of plasma cells based in the bone marrow
- May be designated as either asymptomatic/smoldering or symptomatic, see below
Alternate/Historical Names
- Multiple myeloma
- Myelomatosis
- Medullary plasmacytoma
- Kahler’s disease
Diagnostic Criteria
- Asymptomatic / smoldering vs. symptomatic myeloma are separated based on the presence of complications
- Asymptomatic / smoldering myeloma
requires defined levels of evidence of clonality but lacks complications
- Elevated M protein (>3g/dL) AND/OR
- >10% clonal plasma cells in marrow
- Must not have characteristic clinical complications or end organ/tissue damage
- Symptomatic myeloma requires any level of evidence of clonality plus characteristic complications
- Any level of clonal bone marrow plasma cells (usually >10%) OR
- Any level of M protein in serum or urine
- Usually >3 g/dL IgG or >2.5 g/dL IgA or
- >1 g/24 hr urine light chain
- Must have characteristic clinical complications including:
- Skeletal destruction with osteolytic lesions, pathological fractures, bone pain
- Hypercalcemia, anemia, hyperviscosity
- Renal insufficiency
- Amyloidosis
- (MGUS comprises those cases exhibiting both lower levels of M protein and marrow involvement and lacking complications)
- Asymptomatic / smoldering myeloma
requires defined levels of evidence of clonality but lacks complications
- Variants:
- Non-secretory myeloma (<5% of cases)
- Same as above but absence of M protein by immunofixation electrophoresis; detectable by serum free light chain analysis in 2/3 cases
- Plasma cell leukemia
- Symptomatic plasma cell myeloma WITH
- ≥2K/uL or ≥20% circulating clonal plasma cells (frequently lymphocytoid)
- Frequent extramedullary involvement
- Non-secretory myeloma (<5% of cases)
- Morphologic characteristics
- Distribution: interstitial (clusters not associated with blood vessels), or sheets
- Plasma cell characteristics:
- Eccentric nuclei
- Moderate to abundant basophilic cytoplasm
- Pale perinuclear “hof” representing the golgi zone.
- Variable morphology may be seen:
- Large cells with prominent nucleoli to small cells with “lymphocytoid” appearance
- Monotonous to pleomorphic
- Cytologic atypia:
- While suggestive, is not diagnostic of plasma cell dyscrasia
- Nuclear pleomorphism, blastic chromatin most specific
- Plasmablastic morphology is associated with poorer prognosis
- Large central nucleolus, dispersed chromatin
- High N:C ratio, large nucleus
- Loss of nuclear eccentricity and perinuclear hof
Dita Gratzinger MD PhD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Initial posting and updates:: 9/1/07, 2/23/08, 4/14/10
