Here’s a good question to test your knowledge of myeloma.

Q. Which of the following peripheral blood findings is most common in patients with multiple myeloma?

A. A white blood cell count that includes at least 20% plasma cells
B. A mild thrombocytosis
C. Red cells stacked upon each other like stacks of coins
D. A neutrophilia with a left shift
E. Marked acanthocytosis

See if you can answer before scrolling down to see the correct answer!







(keep scrolling)





The correct answer is C, red cells stacked upon each other like coins. This finding is called rouleaux (check out the image below), and it’s pretty characteristic of myeloma (though it can also be seen in other conditions in which there is a large amount of protein in the blood).


Of the incorrect answers, probably the most commonly-chosen one is A, a white blood cell count that includes at least 20% plasma cells. It’s easy to see that answer and just pick it right off the bat, since myeloma is characterized by an increase in plasma cells.

However, the increase in plasma cells in myeloma is in the bone marrow, not the blood (check out the bone marrow biopsy, above, which is chock-full of plasma cells). The plasma cells in myeloma stay in the bone marrow in almost every case. Seeing plasma cells in the blood in myeloma is extremely rare, and only occurs in end stages of the disease in a few cases.

The things that usually prompt you to consider myeloma (and order a bone marrow biopsy) are the clinical symptoms of anemia, renal failure and bone pain, along with a monoclonal immunoglobulin in the serum and urine (by electrophoresis).

Finally, just as a clarification: you usually do see 20% plasma cells in the bone marrow – but it’s not an official, hard cutoff like it is in acute myeloid leukemia (in which you have to see at least 20% blasts to call it AML). You can make the diagnosis of myeloma if you have fewer than 20% plasma cells but they are all shown to be clonal. Usually you prove that by doing a kappa and lambda stain on a bone marrow section. In normal bone marrow, you see a mixture of both kappa- and lambda-positive plasma cells, but in myeloma the plasma cells will usually be all one type or the other.