Myeloid Sarcoma

A rare type of cancer that mostly affects people who already have acute myeloid leukemia (AML) is called myeloid sarcoma. Unlike other types of blood cancer, myeloid sarcoma affects the soft tissues in the body instead of bone marrow. Usually, doctors recommend similar treatments to those of AML to treat this type of blood cancer.

The bone marrow is a spongy tissue that produces new blood cells, including white blood cells, red blood cells, and platelets. In people with AML, there are some abnormal white blood cells (myeloblasts) that develop in the bone marrow. They can enter the bloodstream and travel throughout the body. Moreover, myeloid sarcoma also contains myeloblasts, but the tumors appear in the lymph nodes, soft tissues, skin, testicles, gastrointestinal tract, and abdominal lining (peritoneum). Check for other names of myeloid sarcoma below:

Chloroma – People with myeloid sarcoma often have an enzyme called myeloperoxidase. The cells of this enzyme often appear green under a microscope.
Granulocytic sarcoma – Certain mature white blood cells are called granulocytes.
Extramedullary myeloid tumor – In such cases, the term “extramedullary” means the outside of the bone marrow.

In general, this type of blood cancer occurs rarely. It affects about 2.5% to 9.1% of people with AML. Furthermore, AML is one of the most common forms of leukemia in adults, but it is rare too. It accounts for approximately 1% of cancer diagnoses each year in the United States. Myeloid sarcoma happens more rarely, and according to some research, it affects about 2 in 1 million adults with AML.

What Are The Symptoms of Myeloid Sarcoma?

This type of blood cancer does not have common symptoms because it may develop anywhere outside the bone marrow. Usually, the symptoms appear when the tumor grows large enough to put pressure on nearby tissues and organs. Check some general symptoms of myeloid sarcoma below:

Unusual weight loss
Appetite changes
Pain
Extreme tiredness (fatigue)
Vomiting
Diarrhea
Bleeding
Protrusion of the eye
Swollen gums

If any of the previous symptoms occur, do not hesitate to see a doctor for a diagnosis. While these symptoms resemble other health conditions, sometimes, they can indicate myeloid sarcoma, especially in people who already have AML.

Causes and Risk Factors

This type of blood cancer occurs when myeloid cells (cells that mature into healthy blood cells) become cancer cells. According to some studies, there is a genetic mutation (change) that causes these cells to become cancerous. When it occurs, and the abnormal cells become too numerous, they can form a mass called a tumor. This tumor can break down and spread throughout the body, affecting other organs and tissues. In such cases, it is called metastatic myeloid sarcoma. Nowadays, experts do not fully understand what exactly causes these genetic mutations.

Usually, people with AML develop myeloid sarcoma, but there are some factors that could increase your risk of developing it. Check some of them below:

Acute myeloid leukemia (AML), including those who have this type of blood cancer in remission.
Chronic myeloid leukemia (CML)
Myeloproliferative neoplasms
Myelodysplastic syndrome
Post-stem cell transplant
Genetic factors
Age – While it may happen at any age, myeloid sarcoma often affects young adults.
High white cell count

What Are The Long-term Effects of Myeloid Sarcoma?

This type of blood cancer may also cause the following complications, especially if the condition is left untreated. Check some examples below:

Progression – People who develop primary myeloid sarcoma (it affects people who do not have AML) almost always progress into AML if it is left untreated.
Increased risk of relapse – One example is extramedullary relapse. It is a serious complication, especially when it occurs after a stem cell transplant.
Organ dysfunction and obstruction – Myeloid sarcoma can appear anywhere in the body and cause problems with organs. The most common complications include gastrointestinal obstruction, but it may also cause blindness (vision loss).
Spinal cord compression – When the tumor occurs in the spine, it may lead to neurological deficits.
Weakened bones and increased risk of fractures
Severe cytopenia and infections

The previous list does not contain a full list of myeloid sarcoma complications. However, you can talk with your physician about measures to reduce the risk or prevent them. Additionally, it is not possible to prevent myeloid sarcoma because doctors do not know the exact cause.

Diagnosis

Usually, the diagnosis starts with a physical examination and questions about medical history and symptoms. Generally, it is difficult to diagnose myeloid sarcoma, and usually it is mistaken for other tumors. To exclude other health conditions that cause similar symptoms to myeloid sarcoma, doctors will perform the following tests and procedures. These include:

CT (computerized tomography) and MRI (magnetic resonance imaging) scans – These are imaging tests used to get detailed images of different tissues and organs in the body.
PET (positron emission tomography) scan – This is another imaging test used to determine how the tumor responds to radiation therapy.
Ultrasound – Commonly, this is the main way to diagnose myeloid sarcoma of the testicles. This test uses sound waves to produce images.
Core biopsy – This procedure involves a guided X-ray that helps the doctor take a sample of the tumor for testing.

Check for other tests used to diagnose myeloid sarcoma below:

Cytogenetic analysis – During this test, doctors will examine cells to check for damaged chromosomes.
Immunophenotyping – This test helps identify specific antigens or markers to determine the type of cancer.
Biopsy – During this test, physicians will take a small sample of the tumor for testing under a microscope. They will look for cancerous cells.
Bone marrow biopsy – This test is similar to the previous, but doctors remove a sample of the bone marrow for testing in this case. The sample is often taken from the pelvic bone or breastbone.

Treatment

To treat this type of blood cancer, doctors often prescribe the same treatments as for AML. Check some examples below:

Chemotherapy – This cancer treatment involves strong medicines that are often given to patients intravenously (IV) to destroy cancerous cells throughout the body.
Radiation therapy – This therapy involves powerful energy beams that help destroy the tumor. Usually, this energy comes from protons or X-rays, but it can also come from other sources. While this treatment can be used before surgery to shrink a large tumor, doctors may recommend it after surgery to destroy cancer cells that may remain even after successful surgery.
Surgery – This treatment is used to remove the tumor, which often helps stop the cancer from growing.
Allogenic hematopoietic stem cell transplant – Doctors may recommend this treatment for people with myeloid sarcoma for healthy stem cells. They help replace cancerous ones.
Targeted therapy – This is another cancer treatment that involves oral medicines that block a specific protein in the cancer cell, causing it to die.

Frequently Asked Questions

Is myeloid sarcoma a blood cancer?

Yes, this is a type of blood cancer, but it does not affect the bone marrow and appears in different parts of the body. Furthermore, most blood cancers do not cause tumors.

Can myeloid sarcoma be cured?

Commonly, myeloid sarcoma requires aggressive treatment similar to that used for AML. In rare cases, treatment can put the cancer into remission. For more details, discuss it with your doctor.

Can myeloid sarcoma turn into leukemia?

Typically, people who develop primary myeloid sarcomas often develop AML, especially if it is found in advanced stages or left untreated. Ask your healthcare provider if you have any other questions.