Acquired aplastic anemia: correlation between etiology, pathophysiology, bone marrow histology and prognosis factors

Aplastic anemia is a clonal disease of stem cell characterized by peripheral blood pancytopenia with hypocellular bone marrow. In most cases acquired aplastic anemia is an autoimmune, T-cell mediated disease (hematopoiesis is mediated by a population of CD8+ T-cells which produce inhibitory cytokines - TNF-alpha, IFN-gamma, IL-6 which suppress hematopoiesis by affecting the mitotic cycle and cell killing by inducing apoptosis). In some cases radiation, medical drugs and chemicals, viruses induce depletion of hematopoietic stem cells by direct toxicity; immune diseases induce complex immune reactions leading to bone marrow failure. Symptoms and signs are represented by fatigue, pallor induces by anemia, infections induce by neutropenia, and bleedings induce by thrombocytopenia. In peripheral blood is present pancytopenia and bone marrow are characterized by hypocellularity, fat cells hyperplasia, residual lymphocytosis, plasmocytosis and mastocytosis. The aim of this study was to establish the correlation between etiology, pathophysiology, bone marrow histology and negative prognosis factors at 16 patients with acquired aplastic anemia (seven with severe aplastic anemia and nine with moderate aplastic anemia) hospitalized in Clinic of Hematology from Craiova between 2003-2008. Eight cases presented idiopathic aplastic anemia and eight cases secondary aplastic anemia (two of them with pure red cell aplasia).

The unfavorable evolution, correlated with etiology and pathophysiology, had been seen at the patients with severe idiopathic aplastic anemia and severe secondary aplastic anemia associated with viral infections and insecticides exposure. Pure red cell aplasia was associated in our study with B19 parvovirus infection or malignant thymoma. The negative prognosis factors in acquired aplastic anemia, correlated with laboratory findings and a low survival, were: severe neutropenia, platelets count less than 10 000/microL, corrected reticulocytes less than 1%, hypocellularity of bone marrow <10%, persistence of pancytopenia at 30 days after initiating therapy.