CHAPTER 1INTRODUCTION

Aplastic anemia is defined as heterogeneous failure, mainly by marrow failure (1). It is firstly founded in 1888. It was found in young, pregnant woman died of severe anemia and neutropenia. Autopsy finding found fatty marrow with essentially no hematopoesis. The term aplasctic anemia was firstly used at 1904. Aplastic anemia itselves is considered as clinical syndrome that further will result in reticulocytopenia, anemia, granulocytopenia, monocytopenia, and thrombocytopenia (3). The diagnosis is based on several laboratory findings with pantocytopenia presence. The findings include with neutrophil count lower than 1.5x109/L, platelet fewer than 50x109/L, haemoglobin concentration less than 10 g/dL, and absolute reticulocyte count fewer than 40x109/L, accompanied with hypocellular marrow without abnormal or malignant fibrosis (3). To do the diagnosis, the required procedure would be biopsy (4). Aplastic anaemia (AA) itself is considered as a rare disease, which cause is idiopathic (yet unknown). The incidence rate of is only ranged from two to six cases per 1 million people per year. The incidence rate in the western country is reported about 2.34 per million per year in barcellona itself, which is 2-3 fold higher than Asia. AA is presented commonly in the second decade of individual life, or around 15 to 25 years, although incidence rate at 60 years old is also inevitable.

DEFINITIONAplastic anemia is a condition that occurs when your body stops producing enough new blood cells. The bone marrow (soft tissue that is located within the hard outer shell of the bones) is responsible for the production of all types of blood cells. The mature forms of these cells include red blood cells, which carry oxygen throughout the body; white blood cells, which fight infection; and platelets, which are involved in clotting. In aplastic anemia, the basic structure of the marrow becomes abnormal, and those cells responsible for generating blood cells (hematopoietic cells) are greatly decreased in number or absent. These hematopoietic cells are replaced by large quantities of fat. Typically, anemia refers to low red blood cell counts, but aplastic anemia patients have lower counts of all three blood cell types: red blood cells, white blood cells, and platelets, termed pancytopenia. Aplastic anemia leaves you feeling fatigued and at higher risk of infections and uncontrolled bleeding. A rare and serious condition, aplastic anemia can develop at any age. Aplastic anemia may occur suddenly, or it can occur slowly and get worse over a long period of time. Treatment for aplastic anemia may include medications, blood transfusions or a stem cell transplant.

EPIDEMIOLOGY

Between 1980 and 2003, a total of 235 cases of aplastic anemia were identified. The overall incidence was 2.34 per million inhabitants per year and the incidence increased with age. Most of the cases were classified as severe or very severe aplastic anemia. Survival rates at 3 months, and at 2 and 15 years after the diagnosis were 73%, 57%, and 51%, respectively. Advanced age and more severe disease at the time of diagnosis were associated with a lower survival rate. There was a trend to a better 2-year survival rate among patients treated with bone marrow transplantation. Forty-nine cases (20.8%) were exposed to drugs reported to be associated with aplastic anemia, and 21 (8.9%) to toxic agents. The International Aplastic Anemia and Agranulocytosis Study and a French study found the incidence rate of acquired aplastic anemia to be about 2 per 1,000,000 persons per year. This approximate annual incidence rate has been confirmed in studies in Spain (Barcelona), Brazil (State of Parana), and Canada (British Columbia). The highest frequency of aplastic anemia occurs in persons between the ages of 15 and 25 years; a second peak occurs between the ages of 65 and 69. Aplastic anemia is more prevalent in the Far East where the incidence is approximately 7 per 1,000,000 in parts of China, approximately 4 per 1,000,000 in sections of Thailand, approximately 5 per 1,000,000 in areas of Malaysia, and approximately 7 per 1,000,000 among children of Asian descent living in a province of Canada. The explanation for a twofold or greater incidence in the Orient compared to the Occident may be multifactorial, but a predisposition gene or genes is a likely component. Studies have not established the use of chloramphenicol in Asia as a cause. Poorly regulated exposure of workers to benzene is a factor, but the attributable risk from benzene and other toxic exposures does not explain the magnitude of the difference in the incidence in Asia compared to that in Europe and South America. A relationship to impure water use in Thailand has led to speculation of an infectious etiology, although no agent, including seronegative hepatitis, a known association with the onset of acquired aplastic anemia, has been identified. Seronegative viral hepatitis is a forerunner of approximately 7 percent of cases of acquired aplastic anemia. The male-to-female incidence ratio of aplastic anemia in most studies is approximately one.

Etiology of Aplastic AnemiaThe most causes of aplastic anemia is unknown (idiopathic). The difficulty in finding the etiology of this disease happens because the natural history takes place slowly. Most of the searching proces of etiology is done through epidemiological studies . Etiology of aplastic anemia can be classified by Acquired Aplastic Anemia and Inherited Aplastic anemia.Acquired Aplastic AnemiaRadiationAplasia of the bone marrow is the main result of acute radiation where the stem cells and progenitor cells damaged. Radiation can damage DNA which active mitotic tissues such as hematopoiesis very sensitif.4, 12 If the stem cells were exposed to the hematopoiesis, aplastic anemia will occurs. Radiation can also affect the bone marrow stroma and cause fibrosis.2Effects of radiation on bone marrow depend on the type of radiation, the dose and the extent of bone marrow exposure to radiation. High-energy radiation can be used as high-dose therapy with no signs of bone marrow damage as long as the radiation field is not the majority of the bone marrow. In patients who received whole-body radiation effects depend on the dose of radiation received. Effects on bone marrow will be a little at a dose of less than 1 Sv (equivalent to 1 Gy or 100 rads for X-rays). The number of blood cells can be reversibly reduced the radiation dose between 1 and 2.5 Sv (100 and 250 rads). Loss of stem cells are irreversibly occur in higher radiation doses. Even patients may die due to damage to the bone marrow radiation dose of 5 to 10 Sv unless the patient receives a bone marrow transplant. Long-term exposure to low doses of external radiation may also cause anemia aplastik.

Chemical Chemicals subtance such as benzene and benzene derivatives associated with aplastic anemia and acute myelositik leukemia (AML). Some chemicals, such as insecticides and heavy metals are also associated with anemia associated with bone marrow damage and pansitopenia.13

DrugsAplastic anemia may occur on the basis of drug hypersensitivity or excessive doses. Practically all drugs can cause aplastic anemia in a person with a genetic predisposition. That often causes aplastic anemia is chloramphenicol. Other drugs are also commonly reported phenylbutazone, sulfur compounds, gold, and anticonvulsants, such as cytotoxic drugs or nitrosourea.2 Note: Drugs with high doses can cause bone marrow aplasia called high risk. Drugs with 30 cases reported to cause aplastic anemia is a medium risk and much more rarely the low risk.

InfectionAplastic anemia can be caused by a viral infection such as viral hepatitis, Epstein-Barr virus, HIV and rubella. Viral hepatitis is the most frequent cause. Severe pancytopenia can occur one to two months after infection with hepatitis. Although rarely aplastic anemia caused by hepatitis but there are relationships between seronegative fulminant hepatitis with aplastic anemia .Parvovirus B19 can cause temporary crisis aplasia in patients with congenital hemolytic anemia (sickle cell anemia, hereditary spherocytosis, etc.)In patients who imuno compromise which failed to produce neutralizing antibodies against parvovirus some form of chronic red cell aplasia may occurred. Viral infections are usually associated with minimal suppression of the bone marrow, usually seen neutropenia and thrombocytopenia bit sparse. Viruses can cause direct damage to the bone marrow that is the infection and hematopoiesis cell cytolysis or indirectly through secondary immune induction, initiation of the autoimmune process that causes a reduction in stem cells and progenitor cells or stromal cells destruction.

Inherited Aplastic AnemiaGenetics FactorsThis group is often called constitutional aplastic anemia and some of it spoken by law Mendell, such as Fanconi anemia. Fanconi anemia is autosomal recessive disorder characterized by hypoplastic bone marrow with brown pigmentation of the skin, hypoplastic thumb or radius , microcephaly, menatal retardation and sexual , kidney disease.

Aplastic anemia in the state/ other DiseaseIn acute lymphoblastic leukaemia sometimes found pancytopenia with marrow hypoplasia.Paroxysmal Nocturnal Hemoglobinuria (PNH) is a disease that can manifest in the form of aplastic anemia. Hemolysis with pancytopenia including abnormalities PNHGestation case of pregnancy with aplastic anemia have been reported, but the relationship between the two conditions is not clear. In some patients, pregnancy exacerbates existing aplastic anemia in which the situation would improve after giving birth. In other cases, aplasia occurs during on the incidence of recurrent pregnancies

Symptoms and Physical Examination of Aplastic AnemiaIn aplastic anemia the is pancytopenia, so the sign and symptoms are caused by pancytopenia. Erythropoetic hypoplastic anemia which will cause the symptoms arise of anemia such weakness, dsypnea, cordial palpitations, tachycardia , pale and others. Reducing elements lead granulocytopenia leukopoesis which will cause the patient to be susceptible to infection, resulting in complaints and symptoms of infection are both local and systemic. Thrombocytopenia can certainly lead to bleeding in the skin, mucous membranes or bleeding in the organ-organ. In most patients, the initial symptoms of aplastic anemia is a frequent complaint of anemia or bleeding, fever or infections. Aplastic anemia may be asymptomatic and discovered on routine examination. Complaints can be found highly variable. In table X shows that bleeding, weak body and dizziness are the most common complaints.

Types of complaint %

Bleeding83

Weakness80

Dizziness69

Palpitations36

Fever33

Low appetite 29

Pale26

Blown23

Blurred vision19

Ear buzzing13

Physical examination in patients with aplastic anemia varies a great deal. In Table 5 shows that pale was found in all patients studied, while bleeding was found in more than half of the patients. Hepatomegaly, which is why an assortment found in a minority of patients, while splenomegaly was not found in any cases. The presence of splenomegaly and lymphadenopathy in fact dubious diagnosis.2

Table 5 shows statistics about physical examination of patients with Aplastic Anemia Physical Examination%

Pale100

Bleeding63

Skin34

Gum26

Retina20

Nose7

Gastrointestinal6

Vagina3

Fever16

Hepatomegaly7

Splenomegaly 0

Laboratory TestsThe initial test for anemia, the complete blood count (CBC), may reveal many abnormal results .Hemoglobin and/or hematocrit may be low.RBC and WBC counts are low.Platelet count is low.Red blood cell indices are usually normal.The differential white blood count shows a decrease in most types of cells but not lymphocytes.Some additional tests that may be performed to help determine the type and cause of anemia include: Reticulocyte countresult is usually low. Erythropoietinusually increased in aplastic anemia. A bone marrow aspiration will show a decrease in the number of all types of mature cells. Tests for infections such as hepatitis, EBV, CMV help to determine the cause. Test for arsenic (a heavy metal) and other toxins Iron tests or tests for vitamin B12 may be done to rule out other causes. Antibody tests such as ANA to determine if the cause is autoimmune disease.

A physical examination or complete medical history may reveal possible causes for aplastic anemia such as exposure to toxins or certain drugs (for example, chloramphenicol) or prior treatment for cancer. Some cases of aplastic anemia are temporary while others have lasting damage to the bone marrow. Treatment depends on the cause. Reducing or eliminating exposure to certain toxins or drugs may help resolve the condition. Medications may be given to stimulate bone marrow production, to treat infections, or to suppress the immune system in cases of autoimmune disorders. Blood transfusions and a bone marrow transplant may be needed in severe cases.

Diagnosis of Aplastic AnemiaTwo main tests are used to diagnose aplastic anemia. Complete blood count (commonly called a CBC). In aplastic anemia this test will show that the red cell count, white cell count, and platelet count are low. Bone marrow biopsy. This test looks at the bone marrow, which contains the blood-forming cells.Complete blood countThe complete blood count (CBC) is a test that measures the different cells in the blood, such as the red blood cells, the white blood cells, and the platelets. This test is done on a sample of blood, usually taken from a vein in your arm. If this test shows that your blood counts are low, other tests may be done to look for the cause. Often the levels of vitamins (like vitamin B12 and folate) and iron will be checked to be sure that low levels arent causing the low blood counts. Poor kidney function can sometimes cause anemia, so blood chemistry tests are often checked as well.If these tests do not find an underlying cause of the low blood counts, you will need to have a bone marrow biopsy.Bone marrow biopsyA bone marrow biopsy has 2 parts: the aspiration and the biopsy. This procedure is usually done while you are lying on your stomach. A part of the pelvic bone (located about 2 inches to the side of the spine) and the skin above it are numbed with local anesthetic. A tiny cut (about 1/8 inch) may be made in the skin to make it easier to insert the needle. Then, for the aspiration, a large needle is placed through the incision into the bone. A syringe is used to remove a small amount of liquid bone marrow (about 1 teaspoon). Even with the numbing medicine, this often causes a brief, sharp pain.For the biopsy, the needle is repositioned and used to remove a small cylinder-shaped piece of bone and marrow (about 1/16 inch in diameter and 1/3 inch long). Both samples usually are taken during the same procedure from the same place in the back of the pelvic (hip) bone. In spite of anesthesia, this procedure may still be uncomfortable.A pathologist, a doctor specializing in diagnosing disease by lab tests, examines the bone marrow under a microscope. A hematologist (internist who specializes in blood diseases) or a hematopathologist (a pathologist who specializes in blood diseases) could also look at the bone marrow sample. Normally, the bone marrow contains many cells that produce the different types of blood cells. Finding an "empty" bone marrow-- that is, one that lacks normal blood-producing cells-- confirms the diagnosis of aplastic anemia. Leukemia or other kinds of cancers can also cause low blood counts, but in that case the bone marrow would be filled with leukemia cells or other cancer cells.Reticulocyte CountA reticulocyte (re-TIK-u-lo-site) count measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate. People who have aplastic anemia have low reticulocyte levels.Other TestsX ray, computed tomography (CT) scan, or an ultrasound imaging test. These tests can show enlarged lymph nodes in your abdomen. Enlarged lymph nodes may be a sign of blood cancer. Doctors also may use these tests to look at the kidneys and the bones in the arms and hands, which are sometimes abnormal in young people who have Fanconi anemia. This type of anemia can lead to aplastic anemia.Chest x ray. This test creates pictures of the structures inside your chest, such as your heart, lungs, and blood vessels. A chest x ray may be used to rule out infections.Liver tests and viral studies. These tests are used to check for liver diseases and viruses.Tests that check vitamin B12 and folate levels in the blood. These tests can help rule out anemia caused by vitamin deficiency. Doctors also may recommend blood tests for PNH and to check your immune system for proteins called antibodies. (Antibodies in the immune system that attack your bone marrow cells may cause aplastic anemia.)

Differential DiagnosisThe main sign of patient with aplastic anemia is pancytopenia (or bicytopenia). Pancytopenia or bicytopenia can occur in other hematology disease. We can not get the prompt diagnosis if we only see the complete blood count test. There are some differential diagnosis of aplastic anemia :1. Aleukemic leukemia2. Myelodysplasia syndrome3. Paroxysmal nocturnal hemogloginuria4. Myeloptisic anemia5. Etc.There is a simple approach of clinical finding of pancytopenia, it is made on the algorithm below.

To get the prompt diagnosis we have to do further ivestigation, like do more spesific examination, like in the table

Therapy

Causal therapyIn many case of aplastic anemia, the cause is still unknown. So that this therapy is rarely use to treat patient with aplastic anemia.Supportive therapyAntibiotic. To prevent or treat the infection we should use antibiotic to replace neutrophils, because patients with AA easily to get some infectious disease.(hematology 2010 & PROF BAKTA)Transfusion. Red cell and platelet transfusions are essential for patients with AA to maintain safe blood counts. Platelet transfusions should be given prophylactically when platelet count is _ 10 _ _109/L or _ 20 __109/L in the presence of fever. (clinical management & hemato 2010 & prof bakta & adi)Androgen and iron chelation. Androgens were used extensively in the treatment of AA for many decades before the availability of immunosupressants. In some patients, oxymetholone can stimulate erythropoiesis and rarely can produce a trilineage response; recent work has shown that androgens increase telomerase by indirect upregulation of the TERT (telomere reverse transcriptase) promoter. Iron overload can cause problems in heavily transfused patients. Subcutaneous desferrioxamine should be started when serum ferritin is _ 1000 _g/L, although evidence for this recommendation is lacking. This also needs to be assessed on an individual basis, in view of the risk of local hemorrhage and infection from subcutaneous injections.hemato 2010

Splenectomy Removal of the spleen does not increase hematopoiesis but may increase neutrophil and platelet counts two- to threefold and improve survival of transfused red cells or platelets in highly sensitized individuals. The surgical morbidity and mortality in patients with few platelets and white cells makes this a questionable therapeutic procedure. Because there are more successful methods of therapy that attack the fundamental problem, this approach would not be used today.Bone marrow function therapy Growth factor. (prof bakta)The use of G-CSF is still discussed because in a recent EBMT study, the association of ATG _ CSA with G-CSF was associated with higher neutrophil counts, and less infection and hospitalization for the duration of G-CSF administration but no study has ever shown an increase in trilineage response by the use of G-CSF. However, prolonged use of growth factors may increase the risk of late clonal disorders, as shown by a retrospective EBMT WPSAA study. (hematology 2010)Hematopoietic growth factors such as granulocyte colony-stimulating factor (G-CSF) should only be used to treat a severe infection that is not responding to antibiotics, although most patients with severe AA will predictably show no increase in neutrophil count. G-CSF should not be used to treat the disease which would otherwise delay definitive treatment with BMT or IST, as there is no rationale for using GCSF in this manner. (adi)Definitive therapyHematopoietic Stem Cell TransplantationThe major curative approach is hematopoietic stem cell transplantation from a histocompatible sibling. In the unusual case of an identical twin donor, conditioning is required to obliterate the immune disease in the recipient, but it can be limited to cyclophosphamide. Marrow stem cells seem to perform better than blood stem cells when used as a source for patients with aplastic anemia, although this is under continued study. Acute and chronic graft-versus-host disease are serious complications, and therapy to prevent or ameliorate them is a standard part of posttransplant treatment. Umbilical cord blood is an alternative source of stem cells from unrelated donors (or, rarely, siblings) for transplantation in children.

The use of high-resolution, HLA typing of a matched, unrelated donor markedly improves the prognosis for transplantation.153 High-resolution DNA matching at HLA-A, -B, -C, and -DRB1 (8 of 8 allele) is considered the lowest level of matching consistent with the highest level of survival. If there is an HLA mismatch at one or more loci, especially HLA-A or -DRB1, the outcome is compromised,153 and immunosuppression with combined therapy may be preferred initially, depending on patient age, cytomegalovirus status, and disease severity. The use of hematopoietic stem cell transplantation can be considered for patients who do not respond or who no longer respond to immunotherapy.

Components of AntiT-Lymphocyte (Immunosuppressive) Therapy Antilymphocyte Serum and Antithymocyte Globulin ATG and ALG act principally by reducing cytotoxic T cells. This involves ATG-induced apoptosis through both FAS and TNF pathways. Cathepsin B also plays a role in T-cell cytotoxicity at clinical concentrations of ATG, but may involve an independent apoptosis pathway. ATG and ALG also release hematopoietic growth factors from T cells. ATG therapy is given daily for 4 to 10 days with doses of 15 to 40 mg/kg. Fever and chills are common during the first day of treatment. Concomitant treatment with glucocorticoids, such as methylprednisolone or dexamethasone lessens the reaction to ATG.ATG treatment may accelerate platelet destruction, reduce the absolute neutrophil count, and cause a positive direct antiglobulin test. This effect may lead to an increase in transfusion requirements during the 4-to 10-day treatment interval. Serum sickness, characterized by spiking fevers, skin rashes, and arthralgias, occurs commonly 7 to 10 days from the first dose. The clinical manifestations of serum sickness can be diminished by increasing the glucocorticoid dose from day 10 to day 17 after treatment. Cyclosporine Administration of cyclosporine, a cyclic polypeptide that inhibits IL-2 production by T lymphocytes and prevents expansion of cytotoxic T cells in response to IL-2, is another approach to immunotherapy. Cyclosporine is administered orally at 10 to 12 mg/kg per day for at least 4 to 6 months. Dosage adjustments may be required to maintain trough blood levels of 200 to 400 ng/mL. Renal impairment is common and may require increased hydration or dose adjustments to keep creatinine values below 2 mg/dL. Cyclosporine also may cause moderate hypertension, a variety of neurological manifestations, and other side effects.Several drug classes interact with cyclosporine to either increase (e.g., some antibiotics and antifungals) or decrease (e.g., some anticonvulsants) blood levels. Responses usually are seen by 3 months and may range from achieving transfusion independence to complete remission. This drug does not require hospitalization or use of central venous catheters. Fewer platelet transfusions are required during the first few weeks of therapy compared to treatment with ALG or ATG.

Combination Immunotherapy Combination treatment of severe aplastic anemia usually includes, for example, ATG, 40 mg/kg per day, for 4 days; cyclosporine, 10 to 12 mg/kg per day, for 6 months and methylprednisolone, 1 mg/kg per day, for 2 weeks. The dose of cyclosporine is adjusted to maintain a trough level of 200400 ng/mL. Prophylaxis for Pneumocystis carinii with daily trimethoprim-sulfamethoxazole or with monthly pentamidine inhalations should be considered for these patients as they receive immunosuppressive therapy.

High-Dose Glucocorticoid Treatment Marrow recovery can occur after very high doses of glucocorticoids.191,192 Methylprednisolone in the range of 500 to 1000 mg daily for 3 to 14 days has been successful, but the side effects, which include marked hyperglycemia and glycosuria, electrolyte disturbances, gastric irritation, psychosis, increased infections, and aseptic necrosis of the hips, can be severe. Glucocorticoids at lower doses commonly are used only as a component of combination therapy for aplastic anemia to ameliorate the toxic effects of ATG and in providing additional lymphocyte suppression.

High-Dose Cyclophosphamide Therapy High-dose cyclophosphamide has been used as a form of immunosuppression.193 Although it would seem inappropriate to administer high doses of chemotherapy to patients with severe marrow aplasia, this approach was based on observations of autologous recovery after preparative therapy for allogeneic transplants. (Hemato 2010 & adi)Other Therapy High doses of intravenous gamma globulin can be used because of its success in treating certain cases of antibody-mediated pure red cell aplasia and lymphocytapheresis to deplete T cells. (adi)

ConclussionAplastic anemia is a rare disease and commonly seen more in males as compared tofemales.Aplastic anemia is a severe type of anemia which can increase morbidity and the mortality rate. Even though severe Severe aplastic anemia is a rare disease, but this disease must be included in the differential diagnosis of patients presenting with pancytopenia. a. With prompt diagnostic evaluation and appropriate initial supportive care,the majority of patients respond to aggressive treatment with immunosuppressive agents. Improvements of current treatment strategies can only be achieved by joint efforts.