Multiple myeloma and myeloid leukemia have much in common. The names are similar, because they are both cancers that start in the bone marrow. Many of the symptoms are similar, and even some of the same drugs are used to treat both diseases. However, they are two distinctly different entities.
Multiple myeloma and myeloid leukemia involve different cell types. Multiple myeloma involve a type of B cell called a plasma cell. The name "myeloma" is somewhat deceiving because this cancer does not involve myeloid cells. It gets its name because it arises in the myelium, or bone marrow. The National Cancer Institute explains that myleloid leukemia arises in myeloblasts, which are derived from the myeloid line of cells. These cells also arise in the bone marrow, but they are not plasma cells.
Although patients with multiple myeloma and myeloid leukemia both suffer from anemia, bruising and infections, MayoClinic.com explains that patients with multiple myeloma suffer bone fractures in parts of the bone where the cancer is lodged. The Leukemia and Lymphoma Society expands on this saying that 90 percent of patients have cancer lodged in different bony locations, which is why it is referred to as "multiple."
To further complicate matters, some patients with multiple myeloma later get a type of myeloid leukemia called acute myeloid leukemia, or AML. In 2006, a group from New York University Medical Center published a paper in the "Archives of Pathology and Laboratory Medicine" describing a 81-year-old man who presented with AML four years after being successfully treated for multiple myeloma. The scientific literature is rife with specific examples of this.