Acute promyelocytic leukemia (APL) is a rare subtype of acute myeloid leukemia (AML). It happens when immature white blood cells called promyelocytes build up in the bone marrow and blood instead of maturing normally. This affects the body’s ability to make healthy blood cells and can lead to problems with bleeding, infection and fatigue.

APL occurs when two genes, PML and RARA, fuse together. This change develops during a person’s lifetime and is not inherited and cannot be passed down to children. APL accounts for a small percentage of all AML cases.

The biggest risk with APL is serious bleeding because the disease can affect the body's ability to form blood clots. This can cause bruising, nosebleeds, gum bleeding or, in some cases, more serious internal bleeding. Because of this risk, treatment is usually started quickly once APL is suspected. APL is a distinct subtype of AML that often responds very well to treatment.

Who gets acute promyelocytic leukemia?

APL can affect people in different ways, but certain patterns are seen in who is most likely to develop it.

• Age: APL can occur at any age but is most often diagnosed in adults.
• Sex: It affects both men and women.
• Genetics: The gene change is not inherited and develops over time.

Types of acute promyelocytic leukemia

Doctors may group APL based on white blood cell counts at diagnosis, which can help guide treatment.

• Low-risk APL: White blood cell counts are lower, and the risk of complications during treatment is lower.
• High-risk APL: White blood cell counts are higher. This can increase the risk of complications, so you need to be monitored closely during treatment.

Although these groups help guide care, both are treated with similar therapies.

Survival and outlook

APL used to be one of the most dangerous forms of leukemia because of the risk of severe bleeding. Today, outcomes are much better, and many people achieve long-term remission when treatment begins promptly.

Acute promyelocytic leukemia symptoms

Symptoms of APL often fall into three main groups:

Bleeding symptoms:

• Easy bruising or bleeding
• Frequent nosebleeds or bleeding gums
• Tiny red or purple spots on the skin (petechiae)
• Heavy menstrual bleeding

Low blood counts:

• Fatigue or weakness
• Pale skin
• Shortness of breath

General symptoms:

• Fever or frequent infections
• Bone or joint pain
• Headaches or dizziness

What does acute promyelocytic leukemia feel like?

People with APL often feel very tired or weak because the body is not making enough healthy blood cells. Some people notice bruising or bleeding without a clear reason, while others develop fevers, infections or shortness of breath. Symptoms can appear quickly.

Other conditions with similar symptoms

APL can look like other types of leukemia, bleeding disorders such as problems with blood clotting, or infections like the flu or pneumonia. Because symptoms can be similar to other conditions, doctors use blood tests and a bone marrow biopsy to confirm the diagnosis.

When to see a doctor

You should seek medical attention right away if you notice unexplained bruising or bleeding, frequent nosebleeds, bleeding gums, unusually heavy menstrual bleeding, persistent fatigue, fever, shortness of breath or repeated infections. Because APL can progress quickly, evaluation and treatment usually begin as soon as it is suspected.

Acute promyelocytic leukemia diagnosis

Getting an accurate diagnosis is important because APL requires prompt treatment.

Diagnosis may include:

• Medical history and physical exam
• Blood tests to check blood counts and look for abnormal cells
• Bone marrow biopsy to confirm diagnosis
• Genetic and molecular testing to look for the PML-RARA change
• Imaging or additional tests if needed

Treatment often begins before all results are confirmed because APL can worsen quickly.

Acute promyelocytic leukemia treatment

Treatment usually starts right away after diagnosis. The goals are to bring the leukemia into remission, prevent complications and support recovery.

Treatment for APL typically takes several months. The first phase, called induction, usually lasts about a month and focuses on achieving remission. This is followed by consolidation, which involves additional treatment cycles over several months to reduce the risk of the disease returning. Some patients also receive a shorter maintenance phase after consolidation. Your care team will give you a timeline based on your specific situation.

Chemotherapy

Chemotherapy drugs kill cancer cells, control their growth or relieve disease-related symptoms. Chemotherapy may involve a single drug or a combination of two or more drugs, depending on the type of cancer and how fast it is growing. In APL, chemotherapy is used together with targeted therapy rather than on its own.

Patients receive chemotherapy through IV infusion. Treatment is given in phases.

The first phase, called induction, focuses on bringing leukemia into remission by reducing the number of leukemia cells in the body. This phase begins soon after diagnosis and is often the most intensive part of treatment. The second phase, called consolidation, involves additional treatment to destroy any remaining leukemia cells and reduce the risk of the disease returning.

The length of each phase and how often treatments are given depend on your specific treatment plan, risk level and overall health. Side effects may include hair loss, fatigue, nausea, low blood counts, infection risk and mouth sores.

Learn more about chemotherapy.

Targeted therapy

Targeted therapy drugs are designed to stop or slow the growth or spread of cancer. This happens on a cellular level. Cancer cells need specific molecules (often in the form of proteins) to survive, multiply and spread. These molecules are usually made by the genes that cause cancer, as well as the cells themselves. Targeted therapies are designed to interfere with, or target, these molecules or the cancer-causing genes that create them.

Targeted therapy works by acting on the specific genetic change that drives APL. It helps immature blood cells mature into normal cells.

Treatment is given daily during induction and then in cycles during consolidation. Some patients may need additional maintenance therapy depending on risk level.

Side effects may include fatigue, nausea, liver changes, low blood counts and differentiation syndrome. Differentiation syndrome is a serious reaction that can occur as leukemia cells mature and release chemicals that cause inflammation in the body. Tell your care team if you develop fever, difficulty breathing or swelling, as this requires prompt medical attention.

Learn more about targeted therapy.

Stem cell transplantation

A stem cell transplant (also known as a bone marrow transplant) is a procedure that replaces cancerous bone marrow with new, healthy bone marrow stem cells. Depending on the cancer, the healthy stem cells can come from a donor or from the patient. Stem cell transplants are usually given after an intense round of chemotherapy that kills the patient’s existing bone marrow cells. Patients usually must stay in the hospital for three to four weeks after the transplant.

In APL, a stem cell transplant is rarely needed because most patients respond well to initial therapy. It may be considered if the disease returns or does not respond to treatment.

Learn more about stem cell transplants.

Clinical trials

Clinical trials are a key part of UT MD Anderson's mission to end cancer. UT MD Anderson uses clinical trials to find better ways to prevent, diagnose and treat cancer. Trials could include new treatments or new combinations of existing treatments.

Doctors will recommend a clinical trial only if they believe it is the best treatment for the patient.

Learn more about clinical trials.

Living with acute promyelocytic leukemia

Treatment for APL often requires hospital stays, particularly during the induction phase. Some patients are admitted for extended periods early in treatment, while others may receive portions of their care as outpatients. Whether you are able to work or maintain your usual routine during treatment depends on your individual situation, the intensity of your treatment and how your body responds. Many patients find they need to reduce or pause work and other activities during active treatment.

• Follow your treatment plan closely, especially early in care.
• Tell your care team right away if you notice new or unusual bruising, bleeding, fever or shortness of breath.
• Keep all follow-up visits and complete all blood tests so your recovery can be monitored.
• Support groups, counseling and education may help you cope during and after treatment.
• A balanced diet, regular activity and rest can support recovery.
• Tracking symptoms and side effects can help guide your care team.

Your care team can also help you plan ahead and connect you with social work and financial counseling resources if needed.

Follow-up and monitoring

After completing treatment, you will have regular follow-up appointments and blood tests to monitor your recovery and watch for any signs of the disease returning. Most people with APL achieve long-term remission, but if APL does return, additional treatment options are available, including stem cell transplantation. Your care team will explain what to watch for and when to call if you have concerns.