What is Aplastic Anemia?

Aplastic anemia, referred to as aplastic anemia, is a group of bone marrow hematopoietic failure syndromes caused by a variety of causes. It is characterized by reduced bone marrow hematopoietic cell proliferation and reduced peripheral blood whole blood cells. Clinically, anemia, bleeding and infection are the main factors. which performed. The exact cause has not been identified, and the incidence of aplastic anemia may be related to chemical drugs, radiation, viral infections and genetic factors. Aplastic anemia is mainly seen in young and middle-aged adults, and its peak incidence is two, namely the age group of 15 to 25 years old and the elderly group of 60 years and older. The incidence is slightly higher in men than in women. According to the severity of bone marrow failure and the progress of clinical course, it is divided into severe and non-severe aplastic anemia and acute and chronic aplastic anemia.

Basic Information

nickname

An obstacle

English name

aplastic anemia

Visiting department

Hematology

Multiple groups

Young people

Common causes

Related to chemical poisons, radiation, viral infections, immunity, etc.

Common symptoms

Mainly manifested by anemia, bleeding and infection

Causes of aplastic anemia

The incidence of aplastic anemia may be related to the following factors:

Drug

Is the most common morbidity factor.

Chemical poison

The relationship between benzene and its derivatives and aplastic anemia has been confirmed by many experimental studies. Benzene is easily fixed in fat-rich tissues when it enters the human body. Benzene is mainly fixed to bone marrow during chronic benzene poisoning. The bone marrow toxicity of benzene is caused by its metabolites The latter can act on hematopoietic progenitor cells, inhibit their DNA and RNA synthesis, and can damage chromosomes.

3. Ionizing radiation

X-rays, gamma rays, or neutrons can pass through or enter cells and directly damage hematopoietic stem cells and the bone marrow microenvironment. Long-term excess allowable radiation exposure (such as a radioactive source accident) can cause aplastic anemia.

4. Viral infection

The relationship between viral hepatitis and aplastic anemia has been confirmed. It is called viral hepatitis-associated aplastic anemia, and it is one of the most serious complications of viral hepatitis. The type of hepatitis that causes aplastic anemia has not been determined so far, mostly due to seronegative hepatitis.

5. Immune factors

Aplastic anemia can be secondary to thymoma, systemic lupus erythematosus, and rheumatoid arthritis. Antibodies that inhibit hematopoietic stem cells can be found in patients' serum. Aplastic anemia for some unknown reasons may also be an immune factor.

6. Genetic factors

Fanconi anemia, congenital keratosis, and Schwachman-Diamond syndrome are mostly autosomal recessive diseases with familial nature.

7. Paroxysmal nocturnal hemoglobinuria (PNH)

PNH is closely related to aplastic anemia, both of which are diseases of hematopoietic stem cells. Clearly change from aplastic anemia to PNH, and the performance of aplastic anemia is no longer obvious; or explicitly change from PNH to aplastic anemia, and the performance of PNH is no longer apparent; -PNH syndrome.

8. Other factors

Rare cases have reported that aplastic anemia develops during pregnancy, resolves after childbirth or induced abortion, and recurs during the second pregnancy, but most consider it to be a coincidence. In addition, aplastic anemia can be secondary to chronic renal failure, severe hypothyroidism or anterior (glandular) pituitary hypofunction.

Clinical manifestations of aplastic anemia

Acute aplastic anemia

Onset is rapid, progress is rapid, often with bleeding and infection as the first and main manifestations. Anemia at the beginning of the disease is often not obvious, but progresses progressively as the course of the disease develops. Almost all have a bleeding tendency, and more than 60% have visceral bleeding, which are mainly manifested as gastrointestinal bleeding, hematuria, fundus hemorrhage (often accompanied by visual impairment), and intracranial hemorrhage. Skin and mucous membrane bleeding is extensive and severe, and it is not easy to control. Fever in the course of the disease is caused by infection. Necrotic ulcers often occur in the oropharynx and around the anus, leading to sepsis. Pneumonia is also common. Infection and bleeding are causal to each other, making the condition worse.

2. Chronic aplastic anemia

Onset is slow, with anemia as the first and main manifestation; bleeding is mostly limited to the skin and mucous membranes, and is not serious; infection can occur concurrently, but it is often dominated by the respiratory tract and is easily controlled. With proper treatment and persistence, many patients can achieve long-term remission and even cure, but some patients have prolonged for many years, even the course of the disease is as long as several decades, and a few of them progress to severe or very severe aplastic anemia in the later period.

Aplastic anemia test

Blood image

There was a decrease in whole blood cells. In a few cases, only 1 or 2 lines of cells were reduced. Anemia is a normal cell type and can also show mild large red blood cells. The red blood cells are slightly different in size, but there is no obvious deformity and polychromaticity, and generally no young red blood cells appear. The absolute value and proportion of reticulocytes were significantly reduced, neutropenia was less than 0.5 × 10 ⁹ / L, and platelets were less than 20 × 10 ⁹ / L.

Bone marrow

Aplastic bone marrow smears show increased oil droplets with naked eyes, emptiness of bone marrow microscopy, and increased non-hematopoietic cells and fat cells, generally above 50%.

Aplastic anemia showed multiple or reduced bone marrow hyperplasia, tertiary hematopoietic cells were significantly reduced, especially megakaryocytes and erythroblasts; non-hematopoietic cells increased, especially lymphocytes increased. Bone marrow images obtained from puncture of different types of chronic parts are very inconsistent, ranging from poor proliferation to hyperplasia, but at least one part has poor proliferation; if the proliferation is good, the proportion of late red blood cells (carbon nuclei) often increases, and its nucleus is irregularly lobed , Showing denucleation disorder, but megakaryocytes were significantly reduced.

3. Bone marrow biopsy and radionuclide bone marrow scan

All patients with aplastic anemia should undergo a bone marrow biopsy to evaluate the bone marrow hematopoietic area. Aplastic bone marrow tissue is yellowish white, with reduced proliferation, mainly adipose tissue, lymphocytes and other non-hematopoietic tissues. The -ray imaging of the whole body bone marrow of 99m sulfide or 111 indium chloride can reflect the distribution of functional bone marrow throughout the body, and the radioactive uptake in the normal bone marrow site is low or even disappeared during aplastic anemia, so it can indirectly reflect the degree and location of hematopoietic tissue reduction.

4. Other inspections

Hematopoietic progenitor cell culture is not only helpful for diagnosis, but also for detecting the presence or absence of suppressor lymphocytes or the presence of inhibitors in serum. Mature neutrophil alkaline phosphatase activity increased, serum lysozyme activity decreased. Acute aplastic anemia is normal or mildly decreased, and chronic aplastic anemia is significantly increased. Except for chromosome aberrations in Fanconi anemia, chromosomal examination is generally normal, and if there is abnormal karyotype, myelodysplastic syndrome must be excluded.

Diagnosis of aplastic anemia

The diagnostic criteria for aplastic anemia revised by the Fourth National Conference on Aplastic Anemia in 1987 are as follows: Whole blood cells decrease, and the absolute value of reticulocytes decreases. Generally no splenomegaly. Bone marrow examination shows reduced or severely reduced hyperplasia in at least one part (if hyperplasia is active, megakaryocytes should be significantly reduced, and non-hematopoietic cells should be seen in the bone marrow small granule components. Those with conditions should be examined for bone marrow biopsy). Can exclude other diseases that cause pancytopenia, such as paroxysmal nocturnal hemoglobinuria, refractory anemia in myelodysplastic syndrome, acute hematopoiesis, myelofibrosis, acute leukemia, and malignant histiocytosis. General anti-anemia drug treatment is ineffective.

Aplastic Anemia Treatment

Including supportive therapy and disease-targeted therapy. The purpose of supportive therapy is to prevent and treat complications related to hemacytopenia; the target therapy is to supplement and replace extremely reduced and damaged hematopoietic stem cells, such as allogeneic hematopoietic stem cell transplantation or immunosuppressive therapy. Intensive immunosuppressive therapy is the first choice for severe aplastic anemia in a 40-year-old, HLA-free contract donor. Non-severe aplastic anemia can be treated with androgens and cyclosporine.