Myeloid Sarcoma

Myeloid sarcoma is a rare disease that’s both a cancerous tumor and a type of blood cancer. It develops when abnormal immature white blood cells (myeloblasts) in your bone marrow multiply to form tumors outside of your bone marrow.

Normally, blood cancer doesn’t cause tumors. But with myeloid sarcoma, you may have tumors in your lymph nodes, under your skin or in your gastrointestinal tract. Less often, the disease may affect your reproductive system, brain or lungs.

This disease can be life-threatening without a prompt diagnosis. But early treatment may slow down how fast it spreads. It may go into remission after treatment.

There’s a close connection between myeloid sarcoma and acute myeloid leukemia (AML). They have the same type of cancer cell. Healthcare providers often use the same medications to treat both diseases. About 1 in 4 people who have AML develop myeloid sarcoma. But you can have this disease without having AML. Providers call this a primary myeloid sarcoma.

This disease has had different names. It’s now known as myeloid sarcoma. But it’s also been called chloroma, granulocytic sarcoma or extramedullary acute myeloid tumor.

Symptoms of myeloid sarcoma

This condition may cause symptoms that include:

• Fatigue
• Losing weight without trying
• Loss of appetite
• Pain where the tumor presses on an organ
• Soft lumps in your lymph nodes or skin

Condition causes

Myeloid sarcoma develops when myeloid cells — which normally mature into healthy blood cells — become cancer cells. A genetic mutation (change) happens that causes myeloid cells to become immature white blood cells called myeloblasts. These cells become a tumor that can form anywhere in your body, damaging nearby tissue.

Researchers aren't sure what causes the change. They're also unsure why myeloid sarcoma forms outside the bone marrow, unlike related blood cancers.

Risk factors

Having AML or other blood cancers increases your risk for myeloid sarcoma. You may also develop it if you have:

• AML that’s in remission
• Chronic myeloid leukemia (CML)
• Myeloproliferative neoplasms
• Myelodysplastic syndrome

Complications of this condition

Without treatment, myeloid sarcoma may cause acute myeloid leukemia in people who don’t have the disease. Other potential complications include:

• Fractures, if the disease spreads to your bones
• Damaged organs, if tumors develop in your intestines, kidneys or lungs
• Neurological issues, if the disease affects your brain

How doctors diagnose this condition

A healthcare provider may start a diagnosis by ruling out other conditions that cause tumors. They may do tests, including:

• Imaging tests: CT and MRI scans can detect issues like benign tumors or abscesses that can be mistaken for myeloid sarcoma. A PET scan may help your provider pinpoint the exact location of the tumor.
• Biopsy: Your provider will get a tissue sample from the tumor. Examining tumor cells under a microscope is the only way to confirm that a tumor is a myeloid sarcoma.
• Immunophenotyping: A medical pathologist will check tumor cells for specific antigens (proteins) on the tumor cells.

Your provider may do a bone marrow biopsy to see if you have AML along with myeloid sarcoma.

How is myeloid sarcoma treated?

You may have a combination of treatments, depending on your situation. Some common treatments are:

• Chemotherapy: This treatment involves medications that kill cancer cells or stop them from multiplying. Healthcare providers may treat myeloid sarcoma with the same medications they use for AML.
• Radiation therapy: You may receive this treatment along with chemotherapy. This treatment destroys cancer cells with focused energy beams.
• Targeted therapy: These are medications that attack specific abnormalities in cancer cells.
• Allogeneic stem cell transplant: In this treatment, you have chemotherapy to destroy abnormal stem cells in your bone marrow. Then, you receive donated healthy stem cells. The donated cells eventually become healthy blood cells.

Your healthcare provider will discuss treatment options. Your specific treatment may depend on factors like:

• The tumor location and size
• The type of changed genes in the tumor cells
• Your age and health
• Whether you also have AML or another type of blood cancer

Your provider will discuss treatment side effects and how long recovery may take.

When should I see my healthcare provider?

Treatment may put myeloid sarcoma into remission. But it often comes back. Your healthcare provider will discuss the symptoms that may mean the disease has returned.

What’s the survival rate for myeloid sarcoma?

Treatments like chemotherapy and allogeneic stem cell transplants can help you live longer with myeloid sarcoma. A recent analysis of cases found that, overall, 39% of people with this disease are alive five years after diagnosis. 

It’s important to remember that this disease can affect people in many ways. You’re unique. Your experience with this disease may be different than what others experience. Your healthcare provider is your best source of information about what you can expect.