Multiple Myeloma: Solitary Plasmacytoma

Solitary plasmacytoma is a rare disorder that is similar to multiple myeloma, although patients do not have myeloma cells in the bone marrow or throughout the body. Instead, patients have a tumor composed of plasma cells that are restricted to a single area of the body — usually the bone, but sometimes an organ.

At Memorial Sloan Kettering, our experts diagnose solitary plasmacytoma when a biopsy of the tumor detects the presence of plasma cells, but additional tests do not reveal signs of multiple myeloma — such as amyloid protein in the blood and urine, or the presence of myeloma cells in the bone marrow.

Our doctors can sometimes cure solitary plasmacytoma of the bone with radiation therapy or surgery to destroy or remove the tumor. However, 70 percent of patients with solitary plasmacytoma eventually develop multiple myeloma and need additional treatment such as chemotherapy, possibly combined with stem cell transplantation.

When this type of tumor develops outside the bone — in the lungs, throat, or other organs — it is called an extramedullary plasmacytoma. For more than half of patients with extramedullary plasmacytoma, the condition is cured with radiation therapy. Less frequently, patients with extramedullary plasmacytoma develop multiple myeloma. Our doctors also can treat this progression of the disease with chemotherapy and, for some patients, stem cell transplantation.