Aplastic anemia is a syndrome of bone marrow failure characterized by peripheral pancytopenia and marrow hypoplasia [1]. It is an uncommon hematopoietic disorder caused by 3 principal mechanisms: defect of stem cells, defect in the microenvironment of the hematopoietic cells, and antibody-mediated mechanisms [2].

Patients with aplastic anemia are classified into non-severe, severe and very severe forms. Severe aplastic anemia is characterized by compromise of at least two cell components, including absolute neutrophil counts (ANC) less than 500 per cubic millimeter, platelet counts less than 20,000 per cubic millimeter, or a corrected reticulocyte count less than 1%. This compromise must occur in patients whose bone marrow biopsy material shows a cellularity of less than 25% or in patients with bone marrow cellularity of 25 to 50% with less than 30% residual hematopoietic cells [3]. In very severe aplastic anemia, the criteria for severe aplastic anemia is fulfilled but the ANC is less than 200 per cubic millimeter. Patients with peripheral pancytopenia that do not fulfill the criteria for severe or very severe forms are classified as non-severe [4].

Aplastic anemia is more common in Asian countries. The annual incidence of aplastic anemia in Europe is 2 per million population. In Thailand, the incidence is 4 per million population in urban areas, and 6 per million population in rural areas. The incidence in Japan is 31 to 48 per million population, while the incidence in China is 19 to 21 cases per million population [5]. The increased incidence in Asian countries is attributed to environmental risk factors rather than genetic factors, since increased incidence is not observed among Asians living in Western countries. There is no gender predilection in aplastic anemia. The disease affects all age groups, with biphasic peaks among patients 10 to 25 years old and patients older than age 60 years [6].

Etiology of aplastic anemia can be classified as congenital or acquired. Congenital causes account for 20% of cases. These causes include Fanconi anemia, dyskeratosis congenita, cartilage-hair hypoplasia, Pearson syndrome, amegakaryocytic thrombocytopenia, Shwachman-Diamond syndrome, Dubowitz syndrome, Diamond-Blackfan syndrome and familial aplastic anemia. Acquired causes account for 80% of cases. These include infections such as hepatitis virus, Epstein-Barr virus, human immunodeficiency virus, parvovirus, and mycobacteria; toxic exposure to radiation and chemicals; transfusion-associated graft-versus-host disease; and eosinophilic fasciitis. Majority of cases are considered idiopathic and classified as acquired aplastic anemia [7].

The most common clinical manifestations of patients with aplastic anemia are consequences of anemia and thrombocytopenia. Anemia manifests as pallor, headache, palpitations, dyspnea, and fatigue. Thrombocytopenia manifests as petechial rashes and mucosal or gingival bleeding. Patients may also present with visual disturbances due to retinal hemorrhage. Infection is a less common presentation. Diagnosis is confirmed using bone marrow aspiration with biopsy [7].

Allogeneic bone marrow transplant from a human leucocyte antigen (HLA)-identical sibling is the treatment of choice for patients less than 40 years old with severe or very severe aplastic anemia. Immunosuppressive therapy using antithymocyte globulin (ATG) and cyclosporine is recommended for patients more than 40 years of age with severe or very severe disease, and for patients with severe or very severe disease less than 40 years old but with no HLA-identical sibling donor. Matched unrelated donor bone marrow transplant may be considered in patients with severe aplastic anemia less than 50 years old who have no matched sibling donors, and have failed at least 1 course of ATG and cyclosporine [7]. The estimated five-year survival rate is 75% for patients receiving immunosuppression and greater than 90% for patients who underwent bone marrow transplantation. The mortality rate for patients given only supportive treatment such as blood transfusions and antibiotics is 70% [8].

Before the introduction of ATG and cyclosporine in the 1980’s, aplastic anemia was treated with androgens and corticosteroids. These treatment modalities are no longer recommended. Androgens may increase erythropoiesis and produce a trilineage response in rare cases, but these are associated with adverse effects such as hepatotoxicity and virilisation [9]. Corticosteroids are ineffective and cause significant adverse effects such as infections and gastrointestinal bleeding [7].

Several international studies reported the clinical profiles of aplastic anemia in children. In a study by Goswami et al. conducted in West Bengal, India, the incidence of aplastic anemia was 1.96 per million population of children per year. Severe aplastic anemia was noted in 33.3% of the cases. The most common etiology was exposure to insecticides, fungicides and fertilizers. The most common symptoms that were found in all patients were weakness and pallor [10]. A 5-year study by Gupta et al. in India reported that 185 patients were diagnosed with aplastic anemia in a single institution. The median age of diagnosis was 8 years old with a male to female ratio of 2.4:1. Pallor (100%), bleeding (83.8%) and fever (73.5%) were the most common presenting symptoms. Of the 185 patients, 70% were classified as severe, 21% as very severe, and 9% as non-severe aplastic anemia. The most common etiology was viral infection, with parvovirus identified in 25.8%, Epstein-Barr virus in 20%, and hepatitis virus in 6.7% of the patients [11].

A study conducted in Serbia that included pediatric and adult patients with aplastic anemia reported that the average age of diagnosis was 40.2 years. The survival rate among patients treated with bone marrow transplantation was significantly better compared to those who received ATG and cyclosporine. Gender and age had no influence on the duration of survival [6].

A Philippine study conducted in 2000 reviewed the profile, survival and outcome of Filipino children with aplastic anemia over a five-year period. Of the 107 patients included in the study, 65% had mild to moderate disease, 30% had severe disease, and 5% had very severe disease. Majority of the patients (77%) were classified as having idiopathic disease. The patients were treated with prednisone and androgens. The median survival time was ten months. The mortality rate after one year was 66.2% for patients with mild to moderate disease and 85.7% for patients with severe to very severe disease [12].

This study will provide data on pediatric patients with aplastic anemia seen in the national tertiary hospital of the Philippines from 2006 to 2013. Through this data, it is hoped that improved awareness about aplastic anemia will increase funding and support for patients with this disease.