Myeloid dysplasia refers to a collection of conditions where the bone marrow, the soft tissue inside bones, fails to produce enough healthy blood cells. This disorder impacts the body’s ability to create functional red blood cells, white blood cells, and platelets.
What is Myeloid Dysplasia
Myeloid dysplasia falls under the umbrella of Myelodysplastic Syndromes (MDS), a group of blood cancers where blood cells in the bone marrow do not mature correctly. The bone marrow produces immature cells that fail to develop into their mature, functional forms.
The core issue in MDS is “ineffective hematopoiesis,” the inefficient production of blood cells in the bone marrow. Instead of maturing into healthy cells, these abnormal cells either die prematurely or are too malformed to function properly, leading to low counts of one or more blood cell types in the bloodstream. The condition spans a spectrum, ranging from milder forms where only one type of blood cell is affected (single lineage dysplasia) to more severe forms where multiple cell lines show abnormalities (multilineage dysplasia).
Recognizing Symptoms and Causes
Symptoms of myeloid dysplasia often arise from the reduced numbers of healthy blood cells. Fatigue and weakness are common due to anemia, which is a low red blood cell count, as red blood cells are responsible for carrying oxygen throughout the body. Frequent infections can occur because of low white blood cell counts, compromising the immune system’s ability to fight off pathogens. Easy bruising or bleeding, such as nosebleeds or tiny red spots under the skin (petechiae), can result from low platelet counts, as platelets are necessary for blood clotting.
In most cases, the exact cause of myeloid dysplasia remains unknown, a situation termed idiopathic. However, certain risk factors have been identified. Advanced age is a significant risk factor, with most patients being over 65 years old, though it can affect younger individuals.
Previous exposure to chemotherapy or radiation therapy for other cancers can also lead to therapy-related MDS. Certain environmental exposures, such as to benzene, are also suspected risk factors. While rare, genetic factors can also contribute to the development of MDS in some instances.
How Myeloid Dysplasia is Diagnosed
The diagnostic process for myeloid dysplasia typically begins with initial blood tests, particularly a complete blood count (CBC). This test often reveals reduced numbers of one or more types of blood cells, such as anemia (low red blood cells), neutropenia (low white blood cells), or thrombocytopenia (low platelets). While a CBC can indicate a problem, it is not sufficient for a definitive diagnosis.
A bone marrow biopsy and aspiration are procedures considered to be the definitive steps for diagnosis and classification. During these procedures, a small sample of bone marrow liquid (aspiration) and solid bone marrow tissue (biopsy) are collected, usually from the hip bone. These samples are then examined under a microscope to assess the morphology, or appearance, of the blood cells and to identify any signs of dysplasia, which refers to abnormal cell shape and appearance. Cytogenetic analysis, which involves examining chromosomes for abnormalities, and molecular testing, which identifies specific gene mutations, are also used to confirm the diagnosis and help predict the disease course.
Treatment Options for Myeloid Dysplasia
Treatment approaches for myeloid dysplasia are highly individualized, depending on the specific type of MDS, the patient’s risk group, and their overall health. Supportive care is a common initial strategy, aiming to manage symptoms and improve quality of life. This often includes blood transfusions to address low red blood cell counts (red blood cell transfusions) or low platelet counts (platelet transfusions). Growth factors, such as erythropoiesis-stimulating agents, can be administered to stimulate the production of certain blood cells. Antibiotics are frequently used to treat or prevent infections that arise from low white blood cell counts.
Low-intensity therapies are often employed to improve blood counts and potentially delay disease progression. Hypomethylating agents, such as azacitidine and decitabine, work by modifying gene expression in bone marrow cells, which can help restore more normal blood cell production. For patients with a specific genetic abnormality involving chromosome 5 (5q deletion), lenalidomide may be a suitable treatment option. These therapies are typically administered over extended periods to achieve and maintain their effects.
In cases of higher-risk MDS, or when the disease progresses, higher-intensity therapies like chemotherapy may be considered. Chemotherapy aims to reduce the number of abnormal cells in the bone marrow. Allogeneic stem cell transplantation is currently the only potentially curative treatment for some patients with myeloid dysplasia. This procedure involves replacing the patient’s diseased bone marrow with healthy stem cells from a donor. Candidacy for transplantation depends on various factors, including the patient’s age, overall health, and the availability of a suitable donor.
Understanding the Disease Progression
Myeloid dysplasia is a variable condition, and its progression differs significantly among individuals. For some, the disease may remain stable for many years, requiring only supportive care to manage symptoms. Regular monitoring by a hematologist, a doctor specializing in blood disorders, is important to track the disease’s stability.
In other individuals, particularly those with higher-risk forms of MDS, the disease has the potential to progress. This progression can involve a worsening of blood cell counts or an increase in the percentage of immature blood cells, known as blasts, in the bone marrow. A significant concern is the potential for myeloid dysplasia to transform into acute myeloid leukemia (AML), a rapidly growing cancer of the bone marrow. Ongoing monitoring allows healthcare providers to adjust treatment strategies as needed based on the disease’s evolution.