Multiple myeloma, also known as Kahler’s disease, is a type of blood cancer. There’s no cure, but treatments can slow its spread and sometimes make symptoms go away. A type of white blood cell called a plasma cell makes antibodies that fight infections in your body. When you have multiple myeloma, these cells multiply the wrong way. They let too much protein (called immunoglobulin) into your bones and blood. It builds up throughout your body and damages your organs. The plasma cells crowd out regular blood cells in your bones. They also send out chemicals that trigger other cells to eat away at your bones. The weak areas that this creates in your bones are called lytic lesions. As multiple myeloma gets worse, the plasma cells spill out of your bone marrow and spread. This causes more organ damage.