There are many types of cells in the human body, and any of them can mutate, and become cancerous. Cells of The immune system are no exception, ironically, even though their one of their jobs is to fight cancer.
The plasma cell is an immune system cell that develops from lymphocytes(B-cells) and specializes in producing “Gamma Globulins”, a type of antibody.

When cancer involves plasma cells In the bone marrow it tends to crowd out the other cells. This can produce bone pain and anemia.
All of the cancer cells come from a single progenitor cell and form a “clone”. This clone produces a large amount of defective protein that would normally be combined with other proteins into the making of antibodies. The large amount of the same protein can often be detected in the urine, as a “Bence Jones” protein.
In modern terminology, the condition is called a “monoclonal gammopathy”. This mass of protein gets into the bloodstream, and can deposit in various tissues, where it is called “amyloidosis”. The kidneys are often damaged in the process of excreting the overproduced, repetitious chains of useless protein.
I had a friend who was a pilot in the military during the Vietnam war. He was around “agent orange”, which was on the news a lot in the 80’s. Agent orange was contaminated by a toxic chemical called Dioxin, which is known to cause cancer. My friend developed a cancer, primary amyloidosis, which is a close relative of multiple myeloma, and in his case produces what is called light chains.
His first warning was an elevated creatinine on a metabolic panel blood test, which pointed to the kidneys. Medical investigation uncovered his plasma cell cancer, and he began treatment. His kidneys eventually started to fail.
His daughter donated one of her kidneys, and currently he’s doing well, since medical treatment curtailed the light chain production.
Please refer to the accompanying Cancer association article on multiple myeloma.
A Mayo clinic article was posted on DWWR on May 25, 2021.