Medullary aplasia

Content

Introduction

Medullary aplasia, also called aplastic anemia, is a disease characterized by the inability of the bone marrow to produce enough blood cells. In the presence of bone marrow aplasia, a simultaneous reduction of red blood cells, white blood cells and platelets is observed. It is a rare and serious disease that affects, on average, one in 500,000 people in Europe.

It can develop at any age, but is more common in teenagers and young adults (20-25 years old). It affects men and women equally. The disease is distinguished in two forms: congenital and acquired. The congenital forms (20%) usually represent the terminal phase of the evolution of a genetic disease (for example, Fanconi's anemia or congenital dyskeratosis). Acquired disease is the most frequent and is estimated to account for 80% of medullary aplasias.

The acquired form can be distinguished on the basis of the origin of the disease in:

  • idiopathic medullary aplasia (when the causes are unknown, 80% of cases)
  • secondary medullary aplasia (when the causes are known, 20%)

The disease is characterized by anemia (causing severe fatigue), a high risk of infections and uncontrolled bleeding. It can appear suddenly and quickly (acute) or slowly over a long period of time. Treatment may include medications, blood transfusions, or bone marrow transplants.

Symptoms

Disorders (symptoms) caused by bone marrow aplasia can include:

  • tiredness
  • shortness of breath
  • tachycardia or arrhythmia
  • pallor
  • frequent or prolonged infections
  • bruising (bruising) with no apparent cause
  • bleeding from the nose or gums
  • prolonged bleeding from wounds
  • skin rashes
  • dizziness
  • headache

The disease can come on suddenly or progress slowly over weeks or months. It can heal quickly or become chronic, up to being very serious and even leading to death in case of infections and bleeding.

Causes

Bone marrow aplasia develops when the bone marrow slows or stops producing new blood cells.

Factors that can temporarily or permanently damage the bone marrow and impair blood cell production include:

  • radiotherapy and chemotherapy: Cancer therapies that kill cancer cells but, at the same time, can damage healthy cells, including stem cells found in the bone marrow. Bone marrow aplasia can be a temporary unwanted effect (side effect) of these treatments
  • toxic chemicals: Exposure to toxic chemicals, such as some of those used in pesticides and insecticides, can cause bone marrow aplasia. Exposure to benzene, a component of diesel fuel, has been associated with the disease. In this case, if subsequent repeated exposure is avoided, the disease can improve
  • medications: some medicines, such as those used to treat rheumatoid arthritis and even some antibiotics, can cause the disease to develop
  • autoimmune diseases: an autoimmune disease in which the immune system begins to affect healthy cells, it can also affect stem cells in the bone marrow
  • viral infectionsViral infections affecting the bone marrow may play a role in the development of bone marrow aplasia in some people. The associated viruses are hepatitis, Epstein-Barr, cytomegalovirus, parvovirus B19 and HIV
  • pregnancy: Medullary aplasia that occurs in pregnancy may be linked to an autoimmune problem that often resolves spontaneously after delivery
  • unknown factors: the doctor is unable to identify the cause of medullary aplasia; in this case we speak of idiopathic medullary aplasia

Links with other diseases

Some people with bone marrow aplasia also have a rare disease called Paroxysmal nocturnal hemoglobinuria (EPN). It is characterized by a drastic reduction in red blood cells which are destroyed by a component of the immune system called complement with consequent leakage of the hemoglobin contained within them (haemolysis). This disease can lead to bone marrow aplasia or bone marrow aplasia can evolve into PNH.

Fanconi anemia is a rare genetic disease which evolves into bone marrow aplasia. Babies who are born with the diagnosis of Fanconi anemia tend to be shorter than normal and have some birth defects, such as underdeveloped limbs. The disease is diagnosed through blood tests.

Diagnosis

To ascertain (diagnose) bone marrow aplasia, your doctor may order some tests which include:

  • blood tests: in healthy people, the number of red blood cells, white blood cells and platelets falls within a specific range of values. Doctors may suspect "bone marrow aplasia when all three of these values ​​are very low."
  • bone marrow biopsy: To confirm bone marrow aplasia, you must undergo a bone marrow biopsy.The biopsy is performed on an outpatient basis or in day hospital, with the patient lying on his side, in a fetal position, on a bed. After performing local anesthesia, or sedation accompanied by painkillers, the doctor inserts a special needle, for a few centimeters, inside a bone of the body (for example, the pelvis) to take a small amount of bone marrow. The sample is then examined under a microscope to exclude the presence of other blood disorders (haematological). If all types of blood cells are decreased, bone marrow aplasia is established
  • cytogenetic analysis: the bone marrow sample taken is sent to a cytogenetics laboratory and analyzed under a microscope by a pathologist for the identification of any chromosomal abnormalities

Therapy

Depending on the severity of the disease, therapies for the treatment of bone marrow aplasia may include:

  • simple observation and periodic control, for minor cases
  • blood transfusions and drug therapies, for the most serious cases
  • bone marrow transplant, in the most serious cases

Severe bone marrow aplasia, which occurs when the number of blood cells is extremely low, can be life-threatening and requires immediate hospitalization to receive appropriate treatment. In addition, severe plastic anemia can develop into myelodysplastic syndromes and leukemic forms.

Blood transfusions

The treatment of medullary aplasia of a certain severity usually involves carrying out blood transfusions to control bleeding and relieve the ailments (symptoms) caused by anemia. Blood transfusions are not, however, a cure the disease, but reduce ailments by supplying the cells that the bone marrow no longer produces in sufficient quantities.

Transfusion can involve:

  • Red blood cells, to increase the number and thus reduce the anemic state and fatigue
  • platelets, to prevent major bleeding

Although there is generally no limit to the number of transfusions that can be practiced, complications can arise with multiple transfusions. The red blood cells received through a transfusion contain iron which can accumulate in the body and damage some vital organs. Iron overload can be treated through the use of drugs that help the body get rid of excess iron (so-called iron chelators) Over time, however, antibodies to the blood cells received with the transfusion could develop, rendering it ineffective and creating further complications. The use of immunosuppressive drugs can reduce this risk.

Bone marrow transplant

Bone marrow transplant, also called stem cell transplantation, is the process of replacing a diseased bone marrow with a healthy one in order to restore normal blood cell production. This type of treatment is particularly indicated in cases of severe bone marrow aplasia and is usually the one chosen for children and young adults who have a compatible donor (very often a sibling).

Once the donor is found, the stem cells present in the sick person's bone marrow are destroyed with radioactive or chemotherapeutic agents and then replaced with healthy stem cells from the donor. Once inoculated into the bloodstream, the healthy cells arrive in the niches present in the bone marrow and begin to generate new blood cells. The transplant involves a long period of hospitalization and it is necessary, immediately afterwards, to take drugs to prevent the rejection of donated stem cells Unfortunately, bone marrow transplantation can cause serious risks with complications that could endanger life itself.

Immunosuppressive drugs

For people who cannot undergo a bone marrow transplant and for those who have "bone marrow aplasia caused by an autoimmune disease," therapy involves the use of drugs capable of suppressing the immune system, the so-called immunosuppressive drugs, such as cyclosporine and anti-lymphocyte globulins (ALG) OR anti-thymocytes (ATG). These medicines block the activity of the immune cells that are destroying the bone marrow and cause it to start making new blood cells. Ciclosporin and the globulins ALG and ATG are often used in combination; some drugs are usually prescribed in combination with these drugs. corticosteroids, such as methylprednisolone. Although immunosuppressive agents can be very effective in treating bone marrow aplasia, they weaken the immune system and, in addition, when stopped, the disease may come back.

Antibiotics and antivirals

Bone marrow aplasia weakens the immune system and having a very low number of white blood cells in circulation exposes the whole body to infection. At the first sign of infection such as, for example, the onset of fever, it is advisable to contact your doctor to fight the infection immediately and prevent it from worsening, putting your life at risk. In the case of a severe form of bone marrow aplasia, the doctor may prescribe antibiotics or antiviral drugs to prevent infections.

Other treatments

Bone marrow aplasia that develops as a result of radio or chemotherapy treatments for cancer usually improves with discontinuation of therapies. The same thing happens for most drugs that can induce bone marrow aplasia.

Pregnant women suffering from bone marrow aplasia are treated with blood transfusions. For many of them, pregnancy-related bone marrow aplasia improves after pregnancy is over.If this does not happen, it is necessary to continue the therapy.

Prevention

Generally, no prevention is possible for most cases of acquired bone marrow aplasia as the underlying cause is not known. However, a small percentage of cases develop from exposure to chemicals. Therefore, avoiding exposure to insecticides, herbicides, organic solvents, paint thinners, and other toxic chemicals can lower the risk of getting sick.

Living with

For those suffering from bone marrow aplasia it is recommended:

  • rest, when necessary. Anemia can cause fatigue and shortness of breath even at the slightest effort. It is good to take breaks and rest when you feel the need
  • avoid contact sports, due to the risk of bleeding associated with a low platelet count, it is best to avoid sports that can cause cuts or falls
  • avoid infections, the risk of infections can be reduced by washing hands frequently and avoiding contact with sick people. In case of fever or other signs of an infection, it is advisable to contact your doctor for the most appropriate therapy

In-depth link

Mayo Clinic. Aplastic anemia (English)

NIH National Heart, Lung, and Blood Institute. Aplastic anemia (English)

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