Multiple myeloma types

Multiple myeloma, also called myeloma, occurs as a result of a cancerous (malignant) white blood cell called a plasma cell. There are two main groups: smoldering and active. Active myeloma includes several subtypes based on the type of immunoglobulin (protein) produced by myeloma cells (malignant plasma cells).

Although multiple myeloma affects the bones, it begins with uncontrolled growth of a population of plasma cells in the bone marrow. Therefore, multiple myeloma is different from bone cancer, which begins in cells that form the hard, outer part of the bone.

Treatment for multiple myeloma depends not only on the type of myeloma, but also on the patient’s symptoms and general health status. Treatment options may include:

• Interventional radiology
• Chemotherapy
• Medications
• Radiation therapy
• Stem cell transplantation
• Targeted therapy
• Immunotherapy
• Surgery
• CAR T-cell therapy

Smoldering multiple myeloma

Smoldering myeloma (also called asymptomatic myeloma) is a slow-growing type of multiple myeloma characterized by increased plasma cells in the bone marrow and the presence of monoclonal proteins, without the presence of symptoms.

Smoldering myeloma typically uses a “watch and wait” approach, which delays treatment until the disease progresses, with close monitoring of diagnostic tests.

Active multiple myeloma

Active multiple myeloma (also called symptomatic myeloma) is characterized by the presence of myeloma signs and symptoms, including:

• A bone or soft tissue tumor containing myeloma cells, also referred to as a plasmacytoma
• Plasma cells comprising at least 60 percent of the blood cells in the bone marrow
• M protein present in urine or blood
• Weakened regions of bone as seen on an X-ray, a condition referred to as osteolytic lesions
• Kidney issues
• Anemia, which occurs when a protein in red blood cells called hemoglobin is lower than it should be
• High amounts of calcium in the blood, referred to as hypercalcemia
• Light chain ratios above 100, as seen in serum testing

Some people with active multiple myeloma may also have osteoporosis (thin bones) or spine fractures.

Immunoglobulins and myeloma

In addition to being diagnosed with either active or smoldering myeloma, patients may be informed of their myeloma subtype. Each subtype is named after the abnormal type of immunoglobulin (Ig) the body is making. These are classified as either a heavy chain or light chain myeloma. Heavy chain myeloma is categorized into five main types, each named after the type of heavy chain (G, A, M, E, or D) present:

• IgG myeloma: About 52 percent of heavy chain myeloma diagnoses are in the IgG category, making it the most common subtype.
• IgA myeloma: This type of myeloma represents approximately 20 percent of heavy chain myeloma diagnoses.
• IgM myeloma: The IgM subtype of myeloma is quite rare, and usually develops as part of a condition called Waldenstrom’s macroglobulinemia (a type of lymphoma).
• IgE myeloma: This type of myeloma is extremely rare, with only 35 known cases globally, and is considered more aggressive than other types, often progressing to plasma cell leukemia.
• IgD myeloma: This very rare myeloma subtype represents just 2 percent of all multiple myeloma diagnoses.

Patients’ myeloma care teams will track their M protein levels throughout their myeloma treatment regimens to evaluate how their bodies are responding to treatment. M protein levels are also important to track after treatment, when scans show no evidence of disease, to look for signs of recurrence (when the myeloma comes back).

Light chain myeloma

Also referred to as "Bence Jones myeloma," light chain myeloma affects approximately 15 percent to 20 percent of myeloma patients. This type of myeloma is typically more aggressive than heavy chain myeloma, and occurs when the monoclonal, malignant plasma cells overproduce only the light chain portion of the immunoglobulin.

Non-secretory myeloma

Non-secretory myeloma is relatively uncommon, affecting 3 percent to 5 percent of multiple myeloma patients. This type of myeloma occurs when myeloma cells produce a very small amount of monoclonal protein. In some cases, these cells produce none of this protein at all.

That’s why doctors won’t be able to track the disease progress using the amount of protein in the patient’s system. Instead, his or her care team will monitor the disease state using other methods, including imaging techniques and possibly bone marrow biopsies.

Rare forms of myeloma

Some patients experience more uncommon types of multiple myeloma:

• Solitary plasmacytoma: This type of myeloma starts with a sole tumor composed of malignant (cancerous) plasma cells, which may lead to multiple myeloma.
• Multiple solitary plasmacytoma: People with this condition have several tumors made of cancerous plasma cells, but the bone marrow may still appear normal. This condition may later lead to a myeloma diagnosis.
• Extramedullary myeloma: Unlike most multiple myeloma instances, extramedullary myeloma affects organs outside the bones, such as the lungs, skin, liver and muscle.

Multiple myeloma relapse

Nearly all multiple myeloma patients experience a relapse at some point during their disease course. This means that the signs of myeloma reappear following treatment. One study published in 2016 noted that among 511 multiple myeloma patients, the average time to relapse was 26.9 months following first-line treatment (the initial treatment course for myeloma). With ongoing research and new treatment approaches, the average time to progression is improving.

The study also noted that early relapse (within 12 months) may be a sign of a worse prognosis, and that patients who relapse early may be strong candidates for clinical trials.

Read more about multiple myeloma relapse.

Next topic: What are the stages of multiple myeloma?