This is what pure red cell aplasia is all about

Aplastic anemia is a common disease in daily life, which is mainly caused by the inability of the body's hematopoietic system to produce normal blood cells. So what is pure red cell aplasia? Many people don’t understand this. In fact, pure red cell aplasia is a syndrome caused by selective aplasia of the red blood cell series in the bone marrow. It is relatively rare in daily life, but it poses a huge threat to human health.

Pure red cell aplasia (purered cellsplasia) is referred to as pure red cell aplasia. It is a rare syndrome caused by selective aplasia of the bone marrow red blood cells. There are more than 100 cases reported in domestic literature. The pathogenesis is mostly related to autoimmunity.

Clinical manifestations

The common clinical manifestation of this disease is progressive severe anemia, which is normocytic or mild macrocytic anemia, accompanied by a significant decrease or absence of reticulocytes, and normal or near-normal numbers of peripheral white blood cells and platelets; the number of nucleated cells in the bone marrow is not reduced, the proliferation of granulocytes and megakaryocytes is normal, but the immature red blood cell series is significantly reduced or even completely lacking.

In some cases, the maturation of the erythroblast series can be seen to be arrested at an early stage, with the appearance of small clusters of proerythroblasts accompanied by megaloblastic changes, but a lack of more mature erythroblasts. Iron dynamics measurement showed that its essence was erythropoiesis disorder.

Clinically, it can be divided into two categories: congenital and acquired. The acquired type can be divided into primary and secondary according to the cause, and divided into acute and chronic according to the course of the disease.

(I) Congenital pure red aplastic anemia

90% of cases develop the disease between birth and 1 year old, and rarely occur after 2 years old. The inheritance pattern is still unclear, and it is familial. The children have slow growth and development, and a few have mild congenital malformations, such as thumb deformities. Unlike Fanconi anemia, they are rarely associated with malignant diseases. The patient's erythroid progenitor cells are not only deficient in number, but also have qualitative abnormalities. Increased HbF, persistent presence of fetal membrane antigen i, and increased activity of purine salvage pathway enzymes indicate defects in nucleic acid synthesis. Patients' lymphocytes can inhibit the growth of normal erythroid progenitor cells in vitro. 20% of cases can achieve spontaneous remission, 60% of patients respond to adrenal cortex hormones, and those who do not respond can also undergo bone marrow transplantation.

(II) Acutely acquired pure red aplastic anemia

Viral infection during the course of chronic hemolytic anemia, especially human parvovirus B19 infection, can selectively inhibit erythroid progenitor cells and cause acute pure red blood cell aplasia, also known as aplastic crisis of hemolytic anemia. In some cases, hematopoietic function temporarily stops after viral infection, leading to pancytopenia and the appearance of giant red blood cells in the bone marrow, also known as acute hematopoietic stagnation. Acute pure red cell aplastic anemia can also occur in children aged 1 to 4 years old, and heal itself after a few weeks without any infectious factors. It is called transient erythroblastopenia in children. Acute pure red aplastic anemia is also seen in viral hepatitis and certain drug-induced diseases, such as phenytoin, azathioprine, chloramphenicol, isoniazid and procainamide. Most cases will recover completely after stopping the drug.

3. Chronic acquired pure red aplastic anemia

Mainly seen in adults. 50% of patients have thymoma, and only 5% of thymoma patients have pure red cell aplasia; most of these thymomas are benign, 70% are spindle cell type, and a few are malignant; they are more common in women (female:male ratio is 3-4.5:1). A few cases may also be secondary to certain autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis, and certain tumors such as chronic lymphocytic leukemia, chronic myeloid leukemia, lymphoma, immunoblastic lymphadenopathy, biliary adenocarcinoma, thyroid cancer, bronchial lung cancer and breast cancer.

Those with unknown causes are called primary acquired pure red blood cell aplasia, which is caused by multiple immune mechanisms leading to the inhibition of erythropoiesis. Anti-erythroblast antibodies, anti-erythropoietin antibodies or inhibitory T lymphocytes exist in the patient's serum. Patients often have multiple immunological abnormalities such as increased or decreased immunoglobulins, monoclonal immunoglobulins, and multiple positive serum antibodies, such as cold agglutinins, cold hemolysins, heterophilic antibodies, antinuclear antibodies, etc. Anti-human globulin test, etc. are positive. Some patients may have decreased function of multiple endocrine glands. Pure erythropoietic anemia without thymoma is more common in males (male:female ratio is 2:1).

Patients with chronic type should all be examined in detail for thymoma. Posteroanterior, lateral and 20-degree oblique chest X-rays are required, which can detect 85% to 90% of thymomas. The detection rate of CT scans can reach 100%. Once the diagnosis of thymoma is established, it should be removed as soon as possible. The remission rate of anemia after surgery can reach 30%. If there is no remission after surgery, administration of cortical hormones or immunosuppressants may be effective.

For primary acquired pure red blood cell aplasia without thymoma, the combined use of adrenal cortex hormones, androgens, and tripterygium wilfordii glycosides can improve the efficacy. If the treatment is ineffective, immunosuppressants should be used in a timely manner, such as azathioprine, cyclophosphamide, 6-mercaptopurine, antilymphocyte globulin or antithymocyte globulin, and cyclosporine A can also be used. It is believed that the combined use of high-dose immunoglobulin and cyclosporine A can improve the efficacy. Those who respond to treatment often develop reticulocytosis 1 to 8 weeks later. The use of immunosuppressants can achieve remission in more than 66% of patients, but the recurrence rate can reach 80%. If various treatments are ineffective, splenectomy can be performed, which is effective in some cases. For those who are ineffective, immunosuppressants may be used after surgery. Plasma exchange can also be used for those with high antibody titers, and danazol (danazol) can also be tried.