Plasma cell neoplasms are diseases in which the body makes too many plasma cells. Plasma cells develop from B lymphocytes (B cells), a type of white blood cell that is made in the bone marrow. Normally, when bacteria or viruses enter the body, some of the B cells will change into plasma cells. The plasma cells make antibodies to fight bacteria and viruses, to stop infection and disease.

Plasma cell neoplasms are diseases in which abnormal plasma cells or myeloma cells form tumors in the bones or soft tissues of the body. The plasma cells also make an antibody protein, called M protein, that is not needed by the body and does not help fight infection. These antibody proteins build up in the bone marrow and can cause the blood to thicken or can damage the kidneys. Plasma cell neoplasms can be benign (not cancer) or malignant (cancer).

The following types of plasma cell neoplasms are cancer:

Signs & Symptoms

  • Plasmacytoma: In this type of plasma cell neoplasm, the abnormal plasma cells (myeloma cells) are in one place and form one tumor, called a plasmacytoma. Sometimes plasmacytoma can be cured. There are two types of plasmacytoma.
    • In isolated plasmacytoma of bone, one plasma cell tumor is found in the bone, less than 10% of the bone marrow is made up of plasma cells, and there are no other signs of cancer. Plasmacytoma of the bone often becomes multiple myeloma.
    • In extramedullary plasmacytoma, one plasma cell tumor is found in soft tissue but not in the bone or the bone marrow. Extramedullary plasmacytomas commonly form in tissues of the throat, tonsil, and paranasal sinuses.

Signs and symptoms depend on where the tumor is. In bone, the plasmacytoma may cause pain or broken bones. In soft tissue, the tumor may press on nearby areas and cause pain or other problems. For example, a plasmacytoma in the throat can make it hard to swallow

  • Multiple myeloma: In multiple myeloma, abnormal plasma cells (myeloma cells) build up in the bone marrow and form tumors in many bones of the body. These tumors may keep the bone marrow from making enough healthy blood cells. Normally, the bone marrow makes stem cells (immature cells) that become three types of mature blood cells:
    • Red blood cells that carry oxygen and other substances to all tissues of the body
    • White blood cells that fight infection and disease
    • Platelets that form blood clots to help prevent bleeding

As the number of myeloma cells increases, fewer red blood cells, white blood cells, and platelets are made. The myeloma cells also damage and weaken the bone.

Sometimes multiple myeloma does not cause any signs or symptoms. This is called smoldering multiple myeloma. It may be found when a blood or urine test is done for another condition. Signs and symptoms may be caused by multiple myeloma or other conditions. Check with your doctor if you have any of the following:

  • Bone pain, especially in the back or ribs
  • Bones that break easily
  • Fever for no known reason or frequent infections
  • Easy bruising or bleeding
  • Trouble breathing
  • Weakness of the arms or legs
  • Feeling very tired
  • A tumor can damage the bone and cause hypercalcemia (too much calcium in the blood). This can affect many organs in the body, including the kidneys, nerves, heart, muscles, and digestive tract, and cause serious health problems.

Hypercalcemia may cause the following signs and symptoms:

  • Loss of appetite
  • Nausea or vomiting
  • Feeling thirsty
  • Frequent urination
  • Constipation
  • Feeling very tired
  • Muscle weakness
  • Restlessness
  • Confusion or trouble thinking.

Multiple myeloma and other plasma cell neoplasms may cause a condition called amyloidosis.

In rare cases, multiple myeloma can cause peripheral nerves (nerves that are not in the brain or spinal cord) and organs to fail. This may be caused by a condition called amyloidosis. Antibody proteins build up and stick together in peripheral nerves and organs, such as the kidney and heart. This can cause the nerves and organs to become stiff and unable to work the way they should.

Amyloidosis may cause the following signs and symptoms:

  • Feeling very tired
  • Purple spots on the skin
  • Enlarged tongue
  • Diarrhea
  • Swelling caused by fluid in your body’s tissues
  • Tingling or numbness in your legs and feet

Treatment

While there is no cure, the cancer can be managed successfully in many patients for years. Treatment for people with symptomatic myeloma includes both treatment to control the disease as well as supportive therapy to improve quality of life, such as by relieving symptoms and maintaining good nutrition. Disease-directed treatment typically includes drug therapy, such as targeted therapy and/or chemotherapy, with or without steroids. Stem cell transplantation may be an option. Other types of treatments, such as radiation therapy and surgery, are used in specific circumstances.

  • Active surveillance for people without symptoms: People with early-stage myeloma and no symptoms may simply be closely monitored by the doctor through checkups. This approach is called active surveillance or watchful waiting. If symptoms appear, then active treatment starts.
  • Chemotherapy: Chemotherapy is the use of drugs to destroy cancer cells, usually by stopping the cancer cells’ ability to grow and divide.
  • Targeted therapy: Targeted therapy is a treatment that targets the cancer’s specific genes, proteins, or the tissue environment that contributes to cancer growth and survival. This type of treatment blocks the growth and spread of cancer cells while limiting damage to healthy cells. In recent years, targeted treatment, sometimes called novel therapy, has proven to be increasingly successful at controlling myeloma and improving prognosis. Researchers continue to investigate new and evolving drugs for this disease in clinical trials.
  • Immunotherapy: Immunotherapy, also called biologic therapy, is designed to boost the body’s natural defenses to fight the cancer. It uses materials made either by the body or in a laboratory to improve, target, or restore immune system function to fight the cancer cells.
  • Other drug therapy: Steroids, such as prednisone and dexamethasone may be given alone or at the same time as other drug therapy, such as with targeted novel therapy or chemotherapy.
  • Bone modifying drugs: Most people with myeloma receive treatment with bone modifying drugs. These drugs help strengthen the bone and reduce bone pain and the risk of fractures.
  • Bone marrow transplantation/stem cell transplantation: A bone marrow transplant is a medical procedure in which bone marrow that contains cancer is replaced by highly specialized cells, called hematopoietic stem cells, that develop into healthy red blood cells, white blood cells, and platelets in the bone marrow. Hematopoietic stem cells are blood-forming cells found both in the bloodstream and in the bone marrow. Today, this procedure is more commonly called a stem cell transplant, rather than bone marrow transplant, because it’s the stem cells in the blood that are typically being transplanted, not the actual bone marrow tissue.
  • Radiation therapy: Radiation therapy is the use of high-energy x-rays or other particles to destroy cancer cells. A doctor who specializes in giving radiation therapy to treat cancer is called a radiation oncologist. The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body. A radiation therapy regimen (schedule) usually consists of a specific number of treatments given over a set period of time.
  • Surgery: Surgery is not usually a disease-directed treatment option for multiple myeloma, but it may be used to relieve symptoms. Surgery is used to treat bone disease, especially if there are fractures, and recent plasmacytomas, especially if they occur outside the bone.