Myeloid sarcoma (chloroma) is a rare cancerous tumor most common in people with acute myeloid leukemia (AML). It’s also a type of blood cancer. Unlike AML and most other blood cancers, myeloid sarcoma forms in your body’s soft tissues instead of your bone marrow. The same therapies used to treat AML are used with myeloid sarcoma.
Myeloid sarcoma, also known as chloroma, is a rare cancerous tumor most commonly diagnosed in people with acute myeloid leukemia (AML). Unlike other blood cancers — including AML — myeloid sarcoma forms outside your bone marrow. Your bone marrow is the spongy tissue in your bones that makes your body's blood cells, including:
With AML, abnormal white blood cells called myeloblasts form in your bone marrow. These cells can spill out and travel through your bloodstream. Similarly, myeloid sarcomas contain myeloblasts. However, these tumors appear most commonly in your lymph nodes, soft tissues, skin, testes, gastrointestinal tract and your abdomen's lining (peritoneum).
Myeloid sarcoma goes by different names:
Myeloid sarcoma is a blood cancer. However, imagining myeloid sarcoma as a blood cancer can be confusing because it's not found where blood cancer forms — in bone marrow. Also, most blood cancers don't involve tumors.
It's helpful to think of myeloid sarcoma in terms of its components. Although it's a solid soft tissue mass, it contains the same type of cancer cells associated with AML and some other types of blood cancers. Related, it responds to treatments that work best for blood-related cancers.
Myeloid sarcoma can affect people of any age or gender, but it’s most common in adults. You’re more likely to develop myeloid sarcoma if you have AML, but people without AML develop myeloid sarcoma in rare cases. A myeloid sarcoma that forms outside of an AML diagnosis is called a primary myeloid sarcoma.
Myeloid sarcoma is rare, affecting anywhere from 2.5% to 9.1% of people diagnosed with AML. While AML is one of the most common types of leukemia in adults, it’s rare, too, making up only 1% of cancer diagnoses each year in the U.S. Myeloid sarcoma is even rarer among people without an AML diagnosis (primary myeloid sarcoma). About 2 out of 1 million adults without an AML diagnosis have myeloid sarcoma.
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Myeloid sarcoma forms when myeloid cells — the cells that normally mature into healthy blood cells — become cancer cells instead. 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 mutation to happen. They're also unsure why myeloid sarcoma forms outside the bone marrow, unlike related blood cancers.
You're most likely to develop myeloid sarcoma if you have a history of acute myeloid leukemia or related blood cancers. People at risk include those:
In people with primary myeloid sarcoma, the tumor may be the first sign of AML.
There aren't common symptoms because myeloid sarcomas can form anywhere outside the blood marrow and affect various organs or tissues. Any symptoms you experience with myeloid sarcoma are likely related to the tumor's size and whether it's impacting a nearby organ.
Common symptoms are nonspecific but may include general symptoms like fatigue, weight loss, loss of appetite or pain, among others, depending on where the myeloid sarcoma develops.
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Your provider will monitor you carefully for myeloid sarcoma if you have AML. It's harder to diagnose myeloid sarcoma without this medical history because these tumors are rare. Providers don't always know to look for them. It's easy to mistake myeloid sarcoma for more common tumors.
An important part of the diagnostic workup involves ruling out common tumors or other lesions. The only way to confirm a diagnosis is to examine the tumor cells closely in a lab.
Your provider may recommend any of the following procedures:
Tests may include:
Treatments for myeloid sarcoma and AML are similar. The specific therapies (or combination of therapies) depend on various factors, including the tumor's location and size, genetic abnormalities in the tumor cells, your age, health and whether you have a co-occurring condition, like AML.
Your provider may recommend:
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Myeloid sarcoma is so rare that scientists haven't gathered enough information yet to know how to prevent it.
Myeloid sarcoma, like AML, is a fast-growing cancer. Without treatment, it can progress quickly, leading to death. However, studies have shown that treatment can slow the progression of myeloid sarcoma, and there’s the potential to put the cancer in remission, a state where your provider can’t identify active cancer on testing. A cure is difficult, but it’s possible and depends on many factors, including how your body responds to treatments. Research has also shown that treatments can help you live longer with a myeloid sarcoma diagnosis.
Your outcomes depend on many factors. These factors include whether you have primary myeloid sarcoma or myeloid sarcoma with AML, your age, your response to chemotherapy, etc. Talk to your provider about how your health and diagnosis will shape your unique treatment outcomes.
You may want to ask your healthcare provider:
A note from Cleveland Clinic
Myeloid sarcoma, like AML, is a fast-growing cancer that often requires aggressive treatment. It’s difficult to cure, but finding the right therapies can slow myeloid sarcoma’s growth and possible progression to AML, if it’s not already present. The right treatments can also put your cancer into remission. Your provider will monitor you closely in case the cancer returns. Ask your provider about the best care plan for your cancer based on your unique case.
Last reviewed on 06/01/2022.
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Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy