Solitary Plasmacytoma
A single localized tumor of plasma cells in bone or soft tissue
Quick Facts
- Type: Plasma cell tumor
- Location: Bone (often spine) or soft tissue
- Key feature: Single tumor, not widespread
- Main treatment: Radiation therapy
Overview
A solitary plasmacytoma is a single, localized mass made up of abnormal plasma cells, the immune cells that normally produce antibodies. Unlike multiple myeloma, which involves plasma cells throughout the bone marrow, a solitary plasmacytoma is confined to one site.
There are two main types. A solitary bone plasmacytoma forms within a bone, most often a vertebra in the spine. An extramedullary plasmacytoma forms in soft tissue outside the bone, frequently in the head and neck area such as the throat or sinuses. Although localized, a solitary plasmacytoma can sometimes progress to multiple myeloma over time, so long-term follow-up is important.
Plasmacytomas belong to the same family of plasma cell disorders as MGUS, smoldering myeloma, and multiple myeloma, and they sit at one point along that spectrum. Because they respond well to treatment directed at the single site, the outlook is often good, but careful staging is needed first to make sure the disease is truly confined to one place and is not part of more widespread myeloma.
Symptoms
Symptoms depend on where the plasmacytoma is located and which structures it presses on.
- Bone plasmacytoma: Localized bone pain, most often in the back, and sometimes a fracture or, if in the spine, nerve compression causing weakness, numbness, or bladder and bowel changes.
- Extramedullary plasmacytoma: A lump or swelling, nasal blockage, nosebleeds, a hoarse voice, or difficulty swallowing when in the head or neck.
Unlike multiple myeloma, a true solitary plasmacytoma does not cause widespread anemia, kidney problems, or high blood calcium. New onset of those features may indicate the disease has spread.
Causes
A solitary plasmacytoma develops when a single clone of plasma cells acquires genetic changes that cause it to grow into a localized tumor. The underlying reason these changes occur is not known.
It is part of the same family of plasma cell disorders as MGUS, smoldering myeloma, and multiple myeloma, and represents one point on that spectrum. It is not inherited in a predictable way and is not caused by anything a person did or any lifestyle factor.
Risk Factors
- Older age, with most cases occurring in adults over 50
- Slightly more common in men
- A background plasma cell disorder in some people
- No established lifestyle or environmental cause
Diagnosis
Diagnosis requires confirming that the tumor is truly solitary and not part of widespread myeloma:
- Biopsy: A sample of the tumor confirms it is made of abnormal (clonal) plasma cells.
- Imaging: MRI and PET-CT or a whole-body scan look for any other lesions to make sure the disease is in one place.
- Bone marrow biopsy: To confirm the marrow elsewhere is not significantly involved.
- Blood and urine tests: Checking for monoclonal protein, calcium, kidney function, and blood counts.
The diagnosis rests on a single proven lesion with no evidence of myeloma-related organ damage elsewhere.
Treatment
Because the disease is localized, treatment is usually directed at the single site, with radiation as the mainstay.
- Radiation therapy: The primary treatment, as plasmacytomas are highly sensitive to radiation and it can control or eliminate the tumor.
- Surgery: Sometimes used to remove a tumor or to stabilize a bone, or to relieve pressure on the spinal cord.
- Systemic therapy: Drug treatment is generally reserved for cases that progress to multiple myeloma.
- Supportive care: Pain control and, where needed, treatment to protect bone or relieve nerve compression.
After treatment, regular follow-up with blood tests and imaging watches for any progression. Radiation is usually well targeted to the affected area, and many people see their tumor and symptoms resolve.
Follow-Up and Living With Plasmacytoma
- Keep all follow-up appointments, since some plasmacytomas later progress to myeloma
- Report new bone pain, fatigue, frequent infections, or numbness and weakness promptly
- Stay active within the limits your care team advises to protect bone health
- Discuss any persistent abnormal protein in your blood, which may need closer monitoring
When to See a Doctor
See a doctor for persistent, localized bone pain, an unexplained lump or swelling, ongoing nasal blockage or nosebleeds, or a hoarse voice that does not resolve.
Seek emergency care if you develop sudden weakness or numbness in the legs, loss of bladder or bowel control, or severe back pain, as these can signal spinal cord compression and require immediate treatment.
Frequently Asked Questions
Is a solitary plasmacytoma the same as multiple myeloma?
No. A solitary plasmacytoma is a single localized tumor, while multiple myeloma involves abnormal plasma cells throughout the bone marrow and causes organ damage. They are related, however, and a plasmacytoma can sometimes progress to myeloma, which is why long-term follow-up is needed.
How is solitary plasmacytoma treated?
Radiation therapy is the main treatment because plasmacytomas respond very well to it. Surgery may be used in some cases to remove the tumor, stabilize a bone, or relieve pressure on the spinal cord. Drug therapy is usually reserved for disease that spreads.
Can a solitary plasmacytoma turn into myeloma?
Yes, a proportion of people with a solitary plasmacytoma later develop multiple myeloma. Regular monitoring with blood tests and imaging is recommended so that any progression is found and treated early.
What is the difference between bone and extramedullary plasmacytoma?
A bone plasmacytoma forms inside a bone, most often a vertebra, and tends to cause bone pain. An extramedullary plasmacytoma forms in soft tissue outside bone, often in the head and neck, and may cause a lump, nasal blockage, or a hoarse voice.
What symptoms are an emergency?
Sudden leg weakness or numbness, loss of bladder or bowel control, or severe back pain can indicate spinal cord compression and require immediate emergency care to prevent lasting nerve damage.
References
- National Cancer Institute (NCI). Plasma Cell Neoplasms (Including Multiple Myeloma) Treatment.
- Leukemia & Lymphoma Society. Plasmacytoma and myeloma.
- Mayo Clinic. Multiple myeloma.
- MedlinePlus, U.S. National Library of Medicine. Plasma cell disorders.