Myeloproliferative neoplasms and splenomegaly

myeloproliferative tumor is a group of disorders in which the body produces too many red or white blood cells or platelets. Often, these disorders cause an enlarged spleen.

If your doctor told you that you have this type of blood disorder, you might be thinking,”Then why is my spleen so big? ” or “What does my spleen have to do with my blood?” even, “What is the spleen? “ These are all good questions.

This article explains the function of the spleen, why the spleen enlarges in myeloproliferative tumors, and describes treatment options splenomegaly (enlarged spleen).

What is the spleen?

The spleen is a relatively small organ (about the size of a fist). It is located on the left side of the abdomen below the ribcage. The spleen consists of two types of tissue:

  • Red pulp filters red blood cells. In the red pulp, old or malformed red blood cells, such as sickle cells, are removed from circulation. Red pulp also helps the body filter infections, especially certain bacterial infections.
  • White pulp is part of the immune system. White plasma helps produce lymphocytes, a type of white blood cell that helps produce antibodies against infection or immunization.

Before birth, the spleen is the main producer of blood cells (hematopoiesis). However, at the end of pregnancy and after birth, the bone marrow takes over this production.

Why does the spleen get bigger

Certain types of myeloproliferative tumors can cause the spleen to enlarge. This enlargement occurs because the spleen cannot function effectively when the body produces too many blood cells. So it overworked and became enlarged.

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polycythemia vera

exist polycythemia vera, producing too many red blood cells, causing the blood to thicken. This increased number of red blood cells then accumulates in the spleen, causing the spleen to enlarge.

primary myelofibrosis

exist primary myelofibrosis, accumulation of abnormal blood cells, causing damage to the bone marrow. In this disease, large numbers of hematopoietic stem cells become blood cells before they fully mature.

This process causes the blood in the bone marrow to thicken, which slows down the ability to make blood cells. So, to make up for the lack of blood cells produced in the bone marrow, the liver and spleen start making blood cells. The extra workload of the spleen makes it bigger.

essential thrombocythemia

In essence thrombocytosis, too many platelets are made in the bone marrow. With this condition, platelets become sticky and clump together, making it difficult for blood to flow. This lump increases the risk of blood clots, stroke, and heart attack. Also, the spleen may become enlarged when blood does not flow adequately.

Symptoms of an enlarged spleen

Many people with an enlarged spleen may not know it, especially if the spleen is only slightly enlarged.

Symptoms of an enlarged spleen include:

  • Satiety: A feeling of “fullness” in the lower left abdomen
  • Stomach upset: When the spleen is visibly enlarged, it can be pressed against the stomach, giving you the feeling of eating only a small amount, like eating a big meal.
  • Injury: The spleen is fragile, usually protected by the chest cavity. As it expands, it is no longer protected and can be prone to injury, especially from car accidents or contact sports such as football or hockey. Trauma to an enlarged spleen can cause profuse bleeding.
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New and Upcoming Treatment Options for Primary Myelofibrosis

Treatment of enlarged spleen

If your spleen is only mildly enlarged, you may not need treatment. Therefore, your doctor may closely monitor your blood counts and spleen size.

If your doctor recommends treatment, there are three options: medication, splenectomy, and radiation therapy.

medical treatment

Generally, drugs for an enlarged spleen work by reducing the production of blood cells. One of the most common drugs used to reduce spleen size in myeloproliferative neoplasms is hydroxyurea.

Other times, doctors use therapy to treat the underlying cause of an enlarged spleen.

These may include:

  • Busulfan
  • Malfalan
  • alpha interferon
  • Thalidomide
  • lenalidomide
  • Prednisone (supported with thalidomide or lenalidomide)

JAK-2 inhibitors, such as the drug ruxolitinib, may be used in some cases.

Second-line treatments include:

  • Cladribine (also known as 2CDA)
  • Daunorubicin
  • Decitabine
  • 5-azacytidine

Treatment depends on your specific diagnosis, other medical problems, and side effects of treatment.

What are my treatment options for polycythemia vera?


After drug treatment, the second treatment option is splenectomy, which is the surgical removal of the spleen.

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The biggest risk of having a spleen removed is the possibility of a serious, life-threatening infection. If you haven’t already, you should get specific vaccines before your splenectomy to protect you from pneumococcal and meningococcal infections. Also, once the spleen has been removed, you may be prescribed antibiotics to prevent these infections.

Radiation Therapy

A third treatment option is radiation therapy (also called radiotherapy). Radiation directed at the spleen can help reduce its size.

These effects are temporary, so splenic radiation therapy is considered palliative care to minimize symptoms to improve quality of life. This therapy may be a good option for people who are not candidates for splenectomy.


Myeloproliferative neoplasms are a group of blood disorders that can lead to an enlarged spleen. If you have an enlarged spleen, you may not notice it at all. Sometimes, however, an enlarged spleen can cause symptoms such as a feeling of fullness in the abdomen, and when it becomes too large to be protected by the chest cavity, the risk of injury increases.

An enlarged spleen does not always require treatment. If you need treatment, it may include medication, surgery to remove the spleen, or radiation to reduce the size of the spleen.

VigorTip words

There are many things to consider when deciding whether or how to treat spleen enlargement in polycythemia vera, primary myelofibrosis, and essential thrombocythemia. Therefore, be sure to discuss the benefits and possible side effects of these treatments with your doctor.