Plasma Cell Neoplasms

Multiple Myeloma

Initial Evaluation

  • Protein electrophoresis
    • SPEP: (serum) quantitates M (monoclonal) component; + in 80% of patients
    • UPEP: (urine) light chain (ie. Bence Jones proteins) detects remaining 20%
  • Immunoelectrophoresis
    • determines M component and determines Ig type
  • BM biopsy
    • Determines plasma cell percent
  • Skeletal survey
    • identify lytic lesions

Major criteria
I. Plasmacytoma on tissue biopsy
II. BM plasmacyosis with > 30% plasma cells
III. M-spike on SPEP or lamda light-chain on UPEP

  • > 3.5 g/dL for IgG
  • > 2.0 g/dL for IgA
  • ≥ 1.0 g/24 h of kepa or lamda on UPEP with amyloidosis

Plasmacytoma

  • < 10% of plasma cell neoplasms
  • similar to multiple myeloma but without bone marrow infiltrate.

solitary plasmacytoma
* when isolated to bone, they are called solitary plasmacytoma or solitary myeloma of bone
* progress to multiple myeloma 44% to 54% of the time at 10 years.
* Dose: 45-50 Gy

extramedullary plasmacytoma
* when found in soft tisses, they are called extramedullary plasmacytoma
* lower conversion to multiple myeloma compared and thus have superior DFS.
* Dose: 45-50 Gy or higher

  1. CNS failure
  2. CNS relapse 34% at 10-years
  3. CNS-prophylaxis with intrathecal chemotherapy or RT
  4. Other site of failure include:
  5. skin, pleura, Waldeyer\’ ring, lung, liver.
  6. 5 year overall survival range from 16% to 65% with median survival of 12 to 24

months.
Minor criteria
a. BM plasmacytosis 10 to 30%
b. M-spike present but not to major criteria levels
c. lytic bone lesions
d. Suppressed uninvolved immunoglobulins:

  • IgM < 50 mg/dL
  • IgA < 100 mg/dL
  • IgG < 600 mg/dL

Diagnosis of Multiple Myeloma
1. One major and one minor criteria (except I + a, II + a, or III + b combinations)
2. Three minor criteria that includes a + b (ie. a + b + c or a + b + d).

Solitary Plasmacytoma

The most strict criteria:

  • no other skeletal lesions on radiographs (MR, CT, bone survey);
  • bone marrow is free of plasma cells; and
  • serum and urine protein electrophoresis are negative

Other criteria:(cox p. 861)

  • Solitary skeletal lesion with or without soft tissue mass
  • Bone marrow plasmacytosis < 10% or 5%
  • Serum and urine eletrophoresis +,- or - post treatment of the lesion.

Treatment

Plasmacytoma of Bone

  • Over 60% progress to myeloma despite radiation
  • Prophylactic regional nodal coverage not needed with 0-4% nodal failures w/o coverage
  • 40-50 Gy is generally used (45 Gy is likely to be a good board answer)

Extramedullary Plasmacytoma

  • Frequently controlled with local radiation with progression of 8-44%
  • Controversial but RT generally cover the regional LN as patients have 10-20% nodal recurrence risk
  • 40-50 Gy is generally used (45 Gy is likely to be a good board answer)
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