Multiple myeloma is a type of blood cancer that develops in plasma cells, a form of white blood cell found in the bone marrow responsible for producing antibodies. In this condition, abnormal plasma cells multiply uncontrollably and accumulate in the bone marrow, interfering with the production of normal blood cells and weakening the immune system. The disease can cause bone pain, fractures, anemia, fatigue, recurrent infections, elevated calcium levels, and kidney dysfunction. Multiple myeloma often affects multiple areas of bone and may produce abnormal proteins that can be detected in blood or urine tests. It primarily occurs in older adults and typically progresses over time, with varying patterns of activity and remission.