There are two categories: congenital and acquired, of which acquired accounts for the vast majority. Congenital aplastic anemia is rare, and the main type is Fanconi anemia. Acquired aplastic anemia can be divided into primary and secondary. The former has unknown causes and accounts for about 50% of acquired aplastic anemia. According to clinical manifestations, hemogram and myelogram, it can also be divided into acute and chronic types. In foreign countries, severe aplastic anemia is classified according to severity, and the latter classification standard requires two of the following three items: ① Absolute value of neutrophils.

The main clinical manifestations of aplastic anemia are anemia, bleeding and infection. The severity of clinical manifestations depends on the degree of hemoglobin, white blood cells and thrombocytopenia, and is also related to clinical types.

1. Acute aplastic anemia is characterized by acute onset, rapid progress and short course of disease, and anemia is often not obvious at the initial stage of onset. However, with the progress of the course of the disease, anemia is getting worse, and there are many obvious symptoms such as fatigue, dizziness and palpitation. Although anemia is difficult to improve after massive blood transfusion. Hemorrhage and infection are often the main symptoms at onset. Almost every case has bleeding, and the bleeding site is extensive. In addition to the surface bleeding of skin mucosa (oral cavity, nasal cavity, gums, bulbar conjunctiva), there are often deep organ bleeding, such as hematochezia, hematuria, vaginal bleeding, fundus bleeding, intracranial bleeding, etc., which often endanger the life of patients. More than half of the cases were infected at the onset, and oropharyngeal infection, pneumonia, skin furuncle, intestinal infection and urinary tract infection were more common. Sepsis can occur in severe cases. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus are the most common pathogens. Infection usually aggravates bleeding and often leads to the death of patients.

2. Chronic aplastic anemia is characterized by slow onset, slow progress and long course of disease. Anemia is the first and main manifestation, and blood transfusion can improve anemia symptoms such as fatigue, dizziness and palpitation. Hemorrhage is generally mild, mostly skin, mucous membrane and other body surface bleeding, deep bleeding is rare. There may be mild infection and fever in the course of the disease, especially respiratory infection, which is easy to control; If the infection is serious and the fever persists, it will often lead to bone marrow failure and turn into severe aplastic anemia.

3. Aplastic diseases

(1) Paroxysmal nocturnal hemoglobinuria (PNH)/ aplastic anemia syndrome: PNH has a strong correlation with aplastic anemia. The two diseases often occur in the same patient at the same time or successively, with similar clinical features, pancytopenia and bone marrow hypoplasia, high incidence in Asia, and effective treatment with immunosuppressants. PNH is characterized by intravascular hemolysis, venous thrombosis and bone marrow hematopoietic failure. Many patients died of thrombosis rather than bleeding complications.

(2) Hepatitis/aplastic anemia syndrome: Aplastic anemia after acute viral hepatitis is not uncommon, and hundreds of cases have been reported so far. Among the patients with aplastic anemia reported in the west, 2% ~ 9% had a history of hepatitis before, and the proportion in Asia may be higher. Although viral hepatitis can sometimes be complicated with mild cytopenia, severe pancytopenia and bone marrow hypoplasia are not common, accounting for less than 0.07% of children's hepatitis and 2% of non-A and non-B hepatitis. In patients with liver failure caused by fulminant seronegative hepatitis, 1/3 will eventually develop aplastic anemia. Aplastic anemia after hepatitis has the following characteristics: ① It often occurs within 1 ~ 2 months after viral hepatitis, with severe whole blood cell reduction in the recovery period of inflammation and light blood cell reduction in the inflammatory period of viral hepatitis, such as granulocytopenia, thrombocytopenia, erythrocytosis and atypical lymphocytosis, which is similar to mild aplastic anemia. Its prognosis is extremely poor, and the mortality rate can reach 90% within 1 year. ② The virus causing aplastic anemia after hepatitis is not clear, and almost all studies show that it is non-A, non-B, non-C and non-G hepatitis virus. Hepatitis C and hepatitis G virus are more common in patients with aplastic anemia, which are mostly considered to be caused by repeated blood transfusion rather than aplastic anemia. ③ There are obvious differences between acute viral hepatitis with negative serum and hepatitis C in clinic, that is, parental contact is not a risk factor, liver function abnormality in patients with acute phase is very serious, and late complications are common. Allogeneic bone marrow transplantation should be the first choice for hepatitis/aplastic anemia syndrome, and intensive immunosuppressive therapy is often effective for patients with obvious immune activation markers.

(3) Pregnancy complicated with aplastic anemia: rare, and it is not clear whether pregnancy is the inducing factor. Hypofunction of spinal cord during pregnancy is more common, pancytopenia often occurs in the first trimester of pregnancy, but recovers after delivery or termination of pregnancy, but a few pregnancies complicated with aplastic anemia can last until postpartum. The survival rate of pregnant women with aplastic anemia is 53%, and the survival rate of infants is 75%. 69% of the patients have a smooth pregnancy process. Therefore, for mothers who insist on continuing pregnancy, intermittent blood transfusion can be used, but pregnancy should be terminated when the condition worsens.

(4) Aplastic anemia after infectious mononucleosis: Infectious mononucleosis caused by acute EB virus infection is often complicated with neutropenia and other hematological abnormalities, but aplastic anemia is rare. Because EB virus infection is the most common viral disease, many people have no obvious clinical symptoms, pancytopenia can be the main manifestation of some infectious mononucleosis in the early or recovery period, and the hemogram of some patients can recover automatically after the symptoms disappear. It is reported that EB virus has been detected in hematopoietic cells of idiopathic aplastic anemia, so the incidence of aplastic anemia after EB virus infection may be higher than previously expected. Antiviral therapy is effective for some patients with aplastic anemia after EB virus infection, and immunosuppressive therapy such as corticosteroids and ATG is also effective for some patients, so it should be applied in the early stage of the disease.

(5) Haemophilus cell syndrome/aplastic anemia syndrome: Patients with hemophilus cell syndrome have hypoplasia of bone marrow, which can be changed from active myelohyperplasia to hypoplasia. 74% of the patients had triple cytopenia, all of them had anemia, 9 1% patients had thrombocytopenia, and 65% patients had neutropenia. Different from typical aplastic anemia, patients with hemophagocytic syndrome/aplastic anemia syndrome all have systemic immune deficiency, malignant tumor and infection. Virus infection is the most common infection, especially herpes virus, others such as cytomegalovirus, herpes simplex virus, varicella-zoster virus, B 19 parvovirus, HIV- 1, followed by bacterial and protozoan infection, and rejection after bone marrow transplantation can also be complicated with hemophagocytic syndrome. The diagnosis depends on tissue biopsy and bone marrow smear. The immune system is activated when hemophagocytic syndrome is accompanied by virus infection, such as the increase of soluble receptors of IFN-γ, TNF-α, IL-6 and IL-2 in peripheral blood, the increase of CD8 negative cells and the increase of IFN-γ produced by T cells in vitro. The clinical application of cyclosporine A(CsA) also shows that T cell-mediated immune enhancement is the pathogenesis of hematopoietic failure.

(6) Graft-versus-host disease after blood transfusion: Aplastic anemia is a common fatal complication of graft-versus-host disease after blood transfusion. Children with congenital immunodeficiency, cancer patients after chemotherapy, and leukemia patients who have received adoptive immunity in recent years, a small amount of donor lymphocytes is enough to produce graft-versus-host disease, which is resistant to immunosuppressant treatment, and hematological manifestations are pancytopenia and myelohypoplasia.

(7) Connective tissue disease: Aplastic anemia may be the clinical manifestation of eosinophilic fasciitis. Eosinophilic fasciitis is a serious connective tissue disease characterized by skin sclerosis. Its pathology is subcutaneous and fascial fibrosis, and its clinical manifestations are scleroderma, eosinophilia, hypergammaglobulinemia, high erythrocyte sedimentation rate and good response to corticosteroid treatment. In addition, both systemic lupus erythematosus and rheumatoid arthritis are reported to be complicated with aplastic anemia, but they are easily confused with drug side effects because of commonly used immunosuppressants.

diagnose

1987 the diagnostic criteria of aplastic anemia revised by the fourth national academic conference on aplastic anemia are as follows: ① the whole blood cell is reduced and the absolute value of reticulocyte is reduced. ② There is generally no splenomegaly. (3) Bone marrow examination shows that at least part of hyperplasia is reduced or severely reduced (if hyperplasia is active, megakaryocytes should be significantly reduced, and non-hematopoietic cells in bone marrow granules are increased). Do a bone marrow biopsy if possible). ④ Other diseases causing pancytopenia can be excluded, such as paroxysmal nocturnal hemoglobinuria, refractory anemia in myelodysplastic syndrome, acute hematopoietic dysfunction, myelofibrosis, acute leukemia and malignant histiocytosis. ⑤ General anti-anemia drugs are ineffective.

The diagnosis basis of aplastic anemia put forward by Institute of Hematology, China Academy of Medical Sciences 1964 was confirmed as the current diagnostic standard of aplastic anemia in China on 1987 after more than 20 years of clinical practice and two revisions in China. Details are as follows.

1. The whole blood cells decreased, and the absolute value of reticulocyte decreased.

2. There is generally no splenomegaly.

3. Bone marrow examination shows that at least part of hyperplasia is reduced or severely reduced.

4. Other diseases that cause pancytopenia can be excluded, such as paroxysmal nocturnal hemoglobinuria, myelodysplastic syndrome, acute hematopoietic dysfunction, myelofibrosis, acute leukemia and malignant histiocytosis.

5. General anti-anemia drugs are ineffective.

(1) Acute aplastic anemia (AAA), also known as severe aplastic anemia type I (SAA Ⅰ Ⅰ);

① Clinical manifestations: acute onset, progressive anemia, often accompanied by severe infection and visceral bleeding.

② Hemogram: In addition to the rapid decrease of hemoglobin, two of the following three items must be met:

A. reticular cells

B. White blood cells decreased significantly, and neutrophils.

C. platelets

③ Bone marrow image:

A. Decreased proliferation in multiple sites: the number of hematopoietic cells in the three lines decreased significantly, and the number of non-hematopoietic cells increased. If the proliferation is active, lymphocytes will inevitably increase.

B. the number of small non-hematopoietic cells and fat cells in bone marrow increased.

(2) Chronic aplastic anemia:

① Clinical manifestations: slow onset, mild anemia, infection and bleeding.

② Hemogram: Hemoglobin decreased slowly, and reticulocyte, leukocyte, neutrophil and platelet were often higher than those of acute aplastic anemia.

③ Bone marrow image:

A. Three-line or double-line reduction: at least part of proliferation is reduced. For example, in the red line with active proliferation, the proportion of carbon nuclei in the late young red zone increased, and megakaryocytes decreased significantly.

B. the number of small fat cells and non-hematopoietic cells in bone marrow increased.

(3) If the condition changes in the course of the disease: the clinical manifestations, hemogram and bone marrow picture are the same as those of acute aplastic anemia, it is called same type.

At present, the diagnostic criteria of severe aplastic anemia (SAA) proposed by Camilta (1976) are still adopted abroad: peripheral blood neutrophils.

The diagnosis of typical cases is not difficult, but the diagnosis can be made according to the clinical manifestations of anemia, bleeding and infection, peripheral blood pancytopenia, bone marrow hyperplasia and other diseases that cause pancytopenia. A few atypical cases can be identified by observing pathological hematopoiesis, bone marrow biopsy, hematopoietic progenitor cell culture, hemolysis test, chromosome, oncogene and radionuclide bone marrow scanning.