Plasmacytoma is a cancer characterized by tumors consisting of abnormal plasma cells growing in bone or soft tissue, according to the Leukaemia Foundation. It may occur as a single mass of abnormal cells, called solitary plasmacytoma, or throughout the body, called multiple myeloma.
Multiple myeloma is actually a cancer of the cells in bone marrow and is treated very differently from solitary plasmacytoma, explains the Leukaemia Foundation. There are two types of solitary plasmacytoma: bone and extramedullary. Solitary bone plasmacytoma occurs on hard tissues and is most common on the spinal column. Over time, many individuals with solitary bone plasmacytoma develop multiple myeloma. Solitary extramedullary plasmacytoma develops into multiple myeloma much less often and occurs in the soft tissues of the body. Common areas of solitary extramedullary plasmacytoma include the upper respiratory tract and gastrointestinal tract.
The cause of plasmacytoma is unknown, and solitary plasmacytoma usually only occurs in middle-aged or older individuals, reports the Leukaemia Foundation. Bone plasmacytomas make up less than 5 percent of all incidences of plasma disorders, and extramedullary plasmacytomas make up even less. Bone plasmacytomas can cause bone fractures or pain. Doctors diagnose plasmacytomas with a biopsy of a tumor, radiographs of the weakened bone or blood tests. Like most other cancers, treatment of plasmacytoma usually includes radiotherapy, but chemotherapy is not as common.