What is the difference between a plasmacytoma and multiple myeloma?

The difference is the number of tumors. Plasma cell neoplasms occur when abnormal plasma cells form cancerous tumors in bone or soft tissue. When there is only one tumor, the disease is called a plasmacytoma. When there are multiple tumors, it is called multiple myeloma.

Both are types of plasma cell neoplasms, so they involve the same kind of abnormal plasma cells. The main difference described here is whether there is a single tumor or many.

Your healthcare team is the best source of information about a specific diagnosis.