Multiple myeloma vs Waldenstrom macroglobulinemia and MGUS
How to tell Multiple myeloma and Waldenstrom macroglobulinemia and MGUS apart when a board question makes them look alike.
Myeloma is CRAB plus plasma cells and lytic lesions; Waldenstrom is IgM hyperviscosity without lytic bone disease; MGUS is M protein without end-organ damage.
Side by side
Multiple myeloma is malignant plasma cell proliferation with monoclonal protein plus end-organ damage: hypercalcemia, renal dysfunction, anemia, and lytic bone lesions.
Waldenstrom macroglobulinemia is lymphoplasmacytic lymphoma with IgM hyperviscosity; MGUS is asymptomatic monoclonal protein without CRAB end-organ damage.
Clonal plasma cells produce monoclonal immunoglobulin or light chains and activate osteoclasts, damaging bone and kidneys.
Waldenstrom produces IgM from lymphoplasmacytic cells, increasing serum viscosity; MGUS is a premalignant clone below symptomatic disease thresholds.
M spike, plasma cells in marrow, Bence Jones proteins, rouleaux, high calcium, renal injury, anemia, and punched-out lytic lesions support multiple myeloma.
IgM spike, hyperviscosity symptoms, and lymphoplasmacytic marrow infiltrate support Waldenstrom; low-level M protein with no CRAB findings supports MGUS.
The trap
An M spike alone does not equal myeloma; end-organ damage, immunoglobulin type, and marrow cell type decide.
Watch it explained
The repair move
For monoclonal proteins, ask whether there is CRAB damage, IgM hyperviscosity, or asymptomatic MGUS.
Try a free question
CoreAn older adult has back pain, anemia, renal dysfunction, hypercalcemia, rouleaux, Bence Jones proteinuria, and punched-out lytic skull lesions. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Multiple myeloma. CRAB findings with plasma-cell monoclonal protein and lytic lesions point to multiple myeloma.
Why the other choices are tempting
- B. Waldenstrom macroglobulinemia causes IgM hyperviscosity and usually not punched-out lytic lesions.
- C. MGUS lacks CRAB end-organ damage.
- D. CLL causes mature lymphocytosis and smudge cells.
- E. Follicular lymphoma causes lymphadenopathy with t(14;18)/BCL2.
Flashcards
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What CRAB findings support multiple myeloma?
Hypercalcemia, renal dysfunction, anemia, and lytic bone lesions support multiple myeloma.
What clue points to Waldenstrom macroglobulinemia?
IgM monoclonal protein with hyperviscosity symptoms points to Waldenstrom macroglobulinemia.
Quick answers
What is the fastest way to tell Multiple myeloma from Waldenstrom macroglobulinemia and MGUS?
Myeloma is CRAB plus plasma cells and lytic lesions; Waldenstrom is IgM hyperviscosity without lytic bone disease; MGUS is M protein without end-organ damage.
What is the key clue for Multiple myeloma?
Multiple myeloma is malignant plasma cell proliferation with monoclonal protein plus end-organ damage: hypercalcemia, renal dysfunction, anemia, and lytic bone lesions.
What is the key clue for Waldenstrom macroglobulinemia and MGUS?
Waldenstrom macroglobulinemia is lymphoplasmacytic lymphoma with IgM hyperviscosity; MGUS is asymptomatic monoclonal protein without CRAB end-organ damage.
What is the common trap with Multiple myeloma vs Waldenstrom macroglobulinemia and MGUS?
An M spike alone does not equal myeloma; end-organ damage, immunoglobulin type, and marrow cell type decide.