Plasma cell myeloma is a type of cancer that occurs in plasma cells, a type of white blood cell. This disease is sometimes referred to as multiple myeloma or Kahler's disease. The term "plasmacytoma" is also used to describe a single tumor of plasma cells, which can progress to plasma cell myeloma if left untreated. Another synonym for plasma cell myeloma is "MM," which stands for multiple myeloma. This term emphasizes the fact that this cancer can affect multiple parts of the body, including the bone marrow, kidneys, and immune system. Understanding these synonyms can help patients and caregivers to communicate more effectively with healthcare providers and each other about this complex disease.