Plasmacytoma

What is a solitary plasmacytoma?

A plasmacytoma is a localised build-up of abnormal plasma cells that occurs either inside (solitary bone plasmacytoma - SBP) or outside the bone (solitary extramedullary plasmacytoma - SEP). The plasma cells associated with plasmacytomas are malignant, which means that a plasmacytoma is considered cancerous. 

Plasma cells are a kind of white blood cell normally found in the bone marrow that produce antibodies to fight infection. Bone marrow is the soft substance found in the centre of larger bones; its main function is to make new blood cells.

Who can get a solitary plasmacytoma?

A solitary plasmacytoma most commonly occurs in middle-aged or elderly people and is very rare under the age of 30.

SBP is twice as common in men as in women. SEP is less common than SBP.

What causes a solitary plasmacytoma?

The exact cause or causes of a plasmacytoma are unknown.

Patients with SBP may develop myeloma at a later time. Myeloma is a type of cancer of plasma cells which are found in the bone marrow.  Patients who do develop myeloma after a SBP generally have a good prognosis.

There is a significantly smaller risk of progression to myeloma with SEP.

What are the signs and symptoms of a solitary plasmacytoma?

The most common sites for a SBP are the spine and the long bones of the arms and legs. When plasmacytoma occurs in bone, the first symptoms patients notice are usually pain and tenderness in the affected bone.

Approximately 90% of SEP occurs in the head and neck, although it is possible for SEP to occur anywhere.  The most common site for an SEP is in the tonsils or at the back of the nose.  It can also occur in the digestive system, the nervous system, bladder, thyroid gland (in the neck), breasts, testicles, salivary glands and lymph nodes (glands).

With an SEP, the symptoms will depend on the particular site; for example, you may experience difficulty with swallowing if the plasmacytoma is found in the upper part of the digestive system.

A diagnosis is confirmed following scans and bloods tests and when myeloma is ruled out.

How are solitary plasmacytomas treated?

The aim of treatment is to eliminate the plasmacytoma. The treatment that is used most commonly for both types of plasmacytoma is radiotherapy. This involves focusing radiation (similar to X-rays) on the plasmacytoma to kill the malignant cells. The treatment is generally given over several days to reduce side-effects; each treatment dose of radiotherapy is known as “a fraction”.

In both kinds of plasmacytoma, chemotherapy is not commonly used. However, in some cases of SBP, the addition of chemotherapy to radiotherapy treatment can be advantageous.

In some SEP patients, surgery to remove the plasmacytoma is an option while some SBP patients may require orthopaedic surgery for surgical stability.

What response should I expect from treatment?

Radiotherapy generally provides excellent local control of the plasmacytoma. However, there does remain the risk of future relapse or progression to myeloma. In general, the risk of progression to myeloma is significantly higher in SBP than SEP. For this reason plasmacytoma patients require long-term follow-up. This generally occurs in the hospital outpatient department and involves regular checks and blood tests.

The future

Hopefully radiotherapy will be all that is required to treat the plasmacytoma and it will not recur or progress into myeloma. However, myeloma, if it were to develop, is now a very treatable cancer in which there have been huge advances in knowledge and treatment over the past 10 years. Plasma cell tumours remain an active area of medical research and further advances in understanding and treatment are expected in the future.