Myeloproliferative Neoplasm: abnormal proliferation of blood cells

Myelodysplastic neoplasm (MPN) is a group of blood cancers characterized by the abnormal proliferation of blood cells from the bone marrow. These conditions arise from genetic mutations in the stem cells of the bone marrow and often go unnoticed for long periods due to their slow development and progression. MPNs are also known as chronic myeloproliferative neoplasm or myeloproliferative disorders and often develop into acute myeloid leukaemia if left untreated. 

Types of MPNs 

The different types of myeloproliferative neoplasm are –

1. Primary myelofibrosis – The abnormal maturation and irregular shape of red blood cells and granulocytes characterizes this blood disorder. Fibrosis or scarring within the bone marrow followed by a decrease in the production of red blood cells and the manifestation of anaemia are seen in this type.
2. Polycythemia vera (PV) is characterized by excessive production of red blood cells in the bone marrow. The resulting accumulation of red blood cells in the bloodstream leads to symptoms such as headaches, dizziness, and an enlarged spleen. Itching throughout the body is another common symptom of polycythemia vera.
3. Essential Thrombocythemia (ET) – It occurs due to excessive platelet production in the bone marrow. In contrast, the production of other blood cell types remains unaffected. The elevated platelet count leads to increased blood stickiness, potentially causing blood flow to slow down.
4. Chronic eosinophilic leukaemia/hypereosinophilic syndrome (HES) – In this condition, an overproduction of eosinophils, a type of white blood cell involved in allergic reactions and parasite defence, is seen. Symptoms of HES include itching, swelling around the eyes and lips, and swollen hands and feet. In some cases, HES may progress rapidly to acute myelogenous leukemia.
5. Systemic mastocytosis (SM) – The abnormal accumulation of mast cells in various tissues throughout the body causes SM. Skin lesions, abdominal pain, and gastrointestinal disturbances are some of the common symptoms of this condition.

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Causes of myeloproliferative neoplasm

The exact aetiology behind myeloproliferative neoplasm remains elusive. However, it has been identified that some specific genetic mutations, including JAK2, CALR, and MPL, are frequently associated with the development of MPNs. These mutations disrupt the normal regulation of blood cell formation in the bone marrow and cause an overproduction of blood cells. 

Some of the major risk factors for developing this MPN are –

• Sex – MPN is more common in men than women, and this might be associated with the increased prevalence of the JAK2 gene in them.
• Occupational Exposure – Exposure to certain chemicals like hydrocarbons, xylene, and benzene increases the risk of developing MPN.
• Smoking
• Obesity
• Family history of MPN
• Exposure to high-dose of radiation

Symptoms

People with myeloproliferative neoplasm usually do not experience any signs and symptoms in the initial stages of the disease. When the disease progresses, some of the common symptoms seen are:

• · Fatigue
• · Loss of weight
• · Frequent infections
• · Blurred or double vision
• · Bleeding from the nose, mouth, and gums
• · Headaches
• · Itchy skin
• · Bone pain
• · Unusual paleness
• · Easy bleeding and bruising
• · Shortness of breath.

Screening Tests: Myeloproliferative Neoplasm

On noticing any abnormality, the physician will first conduct a complete physical exam to rule out other possibilities. If MPN is suspected, additional screening tests are recommended to confirm it. These include:

• Complete blood count (CBC) with differential – A blood sample is taken and examined for the number of blood cells, haemoglobin, and the portion of the blood sample making up the red blood cells.
• Peripheral blood smear: A laboratory test involves spreading a thin layer of blood on a microscope slide for examination. It helps evaluate blood cell morphology and identify abnormalities like changes in the blood cells’ size, shape, or staining patterns. It also helps detect if too much iron is in the red blood cells.
• Cytogenetic analysis is used to study the structure and behaviour of chromosomes. It helps to identify chromosomal abnormalities, such as deletions, duplications, translocations, or rearrangements. Any changes in the chromosome can indicate the presence of cancer.
• Bone marrow biopsy: A sample of the bone marrow is taken from the hipbone or breastbone via biopsy and tested for lymphoma.
• Gene mutation test: In this test, bone marrow or blood samples are tested to detect mutations in the JAK, MPL, or CALR gene.

Treatment for myeloproliferative neoplasm

The standard treatment options available for MPNs are:

• Watchful waiting – In this approach, the patient’s condition is carefully monitored, and no treatment is given until signs or symptoms appear.
• Phlebotomy – It removes the extra blood cells produced in the body. It helps in the treatment of chronic myeloproliferative neoplasms.
• Platelet apheresis – This treatment is recommended for patients with excess platelets in their blood. Blood is taken from the patient, put through a machine that separates the platelets, and finally transfused back into the patient’s body.
• Transfusion therapy – Blood cells from a healthy donor are transfused into the patient to replace the diseased/damaged blood cells.
• Chemotherapy – Chemotherapeutic agents are used to destroy the tumor cells or hamper the disease progression. Commonly used chemotherapeutic drugs for treating MPNs are cyclophosphamide, imatinib, daunorubicin, azacytidine, and decitabine.
• Radiation therapy is recommended for patients experiencing severe discomfort due to an enlarged spleen. Although radiation can help shrink the spleen and alleviate specific symptoms, it does not directly target the underlying myeloproliferative neoplasms.

References

• Poikilocytosis – Wikipedia. https://en.wikipedia.org/wiki/Poikilocytosis
• Blood Cancers (Leukemia and Lymphoma) | Sylvester Comprehensive Cancer Center | University of Miami Health System. https://umiamihealth.org/sylvester-comprehensive-cancer-center/treatments-and-services/pediatric-cancers/blood-cancers-(pediatrics)
• Benefits of Cassava Tape Efficacy for Body Health – THEBOEGIS. https://www.theboegis.com/2020/09/benefits-of-cassava-tape-efficacy-for.html
• https://voice.ons.org/news-and-views/myeloproliferative-neoplasm-symptoms-diagnosis-treatment-and-survivorship