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Myelophthisic Anemia

What Is It, Diagnosis, and More

Author: Nikol Natalia Armata

Editors: Alyssa Haag, Ian Mannarino, MD, MBA

Illustrator: Jillian Dunbar

Copyeditor: Joy Mapes


What is myelophthisic anemia?

Myelophthisic anemia is a type of anemia, a condition caused by a decreased number of red blood cells or dysfunctional red blood cells. Myelophthisic anemia is a kind of normocytic anemia, which means that an individual with this condition will produce red blood cells that are a normal size. However, it is also a hypoproliferative anemia, meaning that the individual will not produce enough of these red blood cells. When blood from an individual with myelophthisic anemia is used for a peripheral blood smear, a microscopic examination of the appearance of blood cells, immature red and white blood cells will be apparent. This accumulation of cells, which are not typically present in the bone marrow, prevents the appropriate production of blood components

The bone marrow is a spongy tissue found in the center of most bones, including the bones of the pelvis, ribs, and sternum. Bone marrow is the primary site of hematopoiesis, the process that produces the various components of the blood. There are two types of bone marrow: yellow and red. Yellow bone marrow is made mostly of fat and contains stem cells that transform into cartilage, fat, or bone cells. Red bone marrow contains blood stem cells that later develop into red blood cells, white blood cells, or platelets. With myelophthisic anemia, the red bone marrow is primarily affected.

What causes myelophthisic anemia?

Myelophthisic anemia usually results from the accumulation in the bone marrow of non-hematopoietic cells, cells that do not help produce blood cells. Most frequently, the bone marrow is infiltrated by tumor cells, such as breast cancer cells, prostate cancer cells, or cells from other hematological malignancies (e.g., acute myeloid leukemia, primary myelofibrosis). 

Inflammatory cells can also accumulate in the bone marrow. This generally occurs in response to chronic inflammation due to conditions such as tuberculosis, sarcoidosis, and rheumatoid arthritis. The inflammatory cells ultimately form granulomatous lesions, collections of immune cells, which cluster together when they can't kill invading pathogens. These lesions interfere with hemopoiesis. 

Additionally, connective tissue can infiltrate the bone marrow in a disorder called “myelofibrosis.” Myelofibrosis may be a result of infections (e.g., tuberculosis), autoimmune diseases (e.g., systemic lupus erythematosus), hypothyroidism (i.e., low levels of thyroid hormones), or hyperthyroidism (high levels of thyroid hormones). 

Lastly, some lipid storage diseases, which are inherited metabolic disorders, can cause lipids to  accumulate in the bone marrow, thereby causing myelophthisic anemia.

An accumulation of non-hematopoietic cells in the bone marrow may replace hematopoietic stem cells, responsible for the production of blood cells, which can lead to an overall deficiency of all blood cells (i.e., pancytopenia). Pancytopenia can somewhat be balanced by extramedullary hematopoiesis, which is when blood cells are made outside the bone marrow.

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What are the signs and symptoms of myelophthisic anemia?

Individuals with myelophthisic anemia may present with common symptoms of anemia, which include weakness, dizziness, and headaches. They may also have increased heart rate (i.e., tachycardia), low blood pressure (i.e., hypotension), as well as cold and pale-colored skin. 

A more detailed examination can reveal pallor, or paleness, of the conjunctiva, which is the tissue that lines the inside of the eyelids; delayed capillary refill, which is the time needed for a finger to regain color after pressure is applied; and enlargement of the spleen, known as splenomegaly. Hepatosplenomegaly, or enlargement of both the liver and spleen, can be found in individuals with myelophthisic anemia, as both organs have a role in extramedullary hematopoiesis. 

Additionally, those with myelophthisic anemia may also present with bleeding diathesis, or a tendency to bleed, due to thrombocytopenia, which is a deficiency of platelets, as well as an increased risk for repeated infections due to leukopenia, which is a deficiency of white blood cells.

How is myelophthisic anemia diagnosed?

In order to diagnose myelophthisic anemia, a detailed review of the individual’s medical history and a physical examination are necessary. Assessment of the individual’s blood tests, peripheral blood smear, and bone marrow biopsy are typically necessary for diagnosis. 

A complete blood count may be conducted to assess the individual’s levels of red and white blood cells, hemoglobin, hematocrit, and platelets, as well as their mean corpuscular volume (MCV), which is a measure of the average volume of an individual's red blood cells. A peripheral blood smear will usually show that the individual’s red blood cells are a typical size, while also revealing the presence of many different types of cells, such as immature cells and cells that have defective shapes (e.g., nucleated red blood cells, teardrop-shaped red blood cells, giant platelets). Bone marrow biopsy may identify signs of infiltration by tumor cells, connective tissue, or inflammatory cells, depending on the underlying cause.

How is myelophthisic anemia treated?

Treatment for myelophthisic anemia varies depending on the underlying cause. For individuals with malignancies, chemotherapy or radiation therapy may be used to decrease the accumulated cancer cells. In cases of myelofibrosis, ruxolitinib, a medication for proper production of blood cells, may be prescribed. Moreover, there are new treatment options for myelophthisic anemia that focus on the interaction between the immune and skeletal systems. For example, pembrolizumab is a drug that has been shown to increase cancer cells’ vulnerability to the body’s immune system, so it may be effective in cases of myelophthisic anemia caused by cancer. 

Treatment can also involve relieving the individual's symptoms. Individuals with myelophthisic anemia frequently have low levels of hemoglobin, which can be addressed by transfusion of packed red blood cells. Transfusions of platelets or administration of leukocyte-stimulating medications are rarely advised unless there is severe concurrent bleeding or infection.

What are the most important facts to know about myelophthisic anemia?

Myelophthisic anemia is a normocytic, hypoproliferative anemia characterized by the presence of immature blood cells in the blood, which occurs because non-hematopoietic cells have infiltrated the bone marrow. Most frequently, tumor cells, lipids, inflammatory cells, or connective tissue are the infiltrators. Individuals with myelophthisic anemia may present with common symptoms of anemia as well as hepatosplenomegaly. Diagnosis is based on the individual’s medical history and physical examination, as well as the individual’s complete blood count, peripheral blood smear, and bone marrow biopsy. Treatment for myelophthisic anemia depends on the underlying cause.

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Related links

Aplastic anemia
Myelodysplastic syndromes
Non-hemolytic normocytic anemia: Pathology review
Bone histology
Anemia: Clinical practice

Resources for research and reference

Ashorobi, D., & Munakomi, S. (2021, May 1). Myelophthisic anemia. In StatPearls [Internet]. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK541103/ 

Incyte Corporation. (n.d.).  Jakafi for polycythemia vera. In Jakafi - ruxolitinib (tablets). https://www.jakafi.com/polycythemia-vera/pv-treatment

McLarnon, A. (n.d.). Bone marrow. In British Society for Immunology: BiteSized immunology. https://www.immunology.org/public-information/bitesized-immunology/organs-and-tissues/bone-marrow  

National Cancer Institute. (n.d.). Bone marrow. In NCI dictionary of cancer terms. https://www.cancer.gov/publications/dictionaries/cancer-terms/def/bone-marrow   

Office of Communications and Public Liaison, National Institute of Neurological Disorders and Stroke (NINDS). (2018). Lipid storage diseases fact sheet. https://www.ninds.nih.gov/disorders/patient-caregiver-education/fact-sheets/lipid-storage-fact-sheet