In multiple myeloma, abnormal plasma cells build up inside bone marrow -- the spongy tissue inside large bones where blood cells are produced. Over time, myeloma cells cause damage to bones, kidneys, ...

Medically reviewed by Doru Paul, MD Key Takeaways Myeloproliferative neoplasms cause too many blood cells in the body.Symptoms depend on which type of blood cell is overproduced, but often include ...