Aplastic Anemia Overview
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Questions and Answers

Define aplastic anemia and describe its primary clinical feature.

Aplastic anemia is a bone marrow failure syndrome characterized by peripheral pancytopenia, which is a decrease in red blood cells, white blood cells, and platelets.

List at least three congenital causes of aplastic anemia.

Three congenital causes include Fanconi anemia, Dyskeratosis congenita, and Diamond-Blackfan anemia.

What role does autoimmune T-cell activity play in aplastic anemia?

Autoimmune T-cell activity is suggested to be a mediating factor in the primary (idiopathic) form, contributing to the destruction of hematopoietic stem cells.

How can Fanconi anemia be diagnosed in patients?

<p>Fanconi anemia can be diagnosed by observing elevated chromosomal breakage after exposing peripheral blood lymphocytes to a DNA cross-linking agent like DEB or mitomycin C.</p> Signup and view all the answers

Differentiate between the primary (idiopathic) and secondary causes of aplastic anemia.

<p>Primary causes are mostly idiopathic and thought to be autoimmune, while secondary causes may result from external factors such as chemicals, medications, or infections.</p> Signup and view all the answers

What are the common lab features seen in patients with aplastic anemia?

<p>Common lab features include low levels of red blood cells, white blood cells, and platelets, indicating pancytopenia.</p> Signup and view all the answers

What is the typical treatment approach for Fanconi anemia?

<p>The typical treatment for Fanconi anemia includes androgens or stem cell transplantation.</p> Signup and view all the answers

Explain why patients with aplastic anemia are at risk for myelodysplastic syndromes or acute myeloid leukemia.

<p>Patients with aplastic anemia, particularly those with Fanconi anemia, are at increased risk due to the underlying genetic instability and impaired bone marrow function.</p> Signup and view all the answers

Describe the age range typically associated with the presentation of Fanconi anemia.

<p>Fanconi anemia typically presents in patients between the ages of 3 to 14 years, although some cases may be identified in adulthood.</p> Signup and view all the answers

What impact do congenital defects have on patients with aplastic anemia?

<p>Congenital defects in patients with aplastic anemia can include growth retardation and skeletal abnormalities, which are often associated with underlying syndromes like Fanconi anemia.</p> Signup and view all the answers

What are the key differences between inevitable and idiosyncratic aplastic anemia caused by cytotoxic drugs?

<p>Inevitable aplastic anemia is dose-related and predictable, while idiosyncratic aplastic anemia is unpredictable and occurs in a minority of exposed individuals.</p> Signup and view all the answers

Describe the common clinical features associated with aplastic anemia.

<p>Common clinical features include anemia, thrombocytopenia, and neutropenia, leading to symptoms like fatigue, bruising, and increased infection risk.</p> Signup and view all the answers

What is the role of immune mechanisms in the pathogenesis of aplastic anemia?

<p>Immune mechanisms may involve autoreactive T-cells and immune-mediated suppression of hematopoiesis, contributing to stem cell failure.</p> Signup and view all the answers

Identify the viruses commonly associated with aplastic anemia and their effect on patients.

<p>Common viruses include viral hepatitis, EBV, herpes simplex, and parvovirus, which can induce aplastic anemia particularly in patients with hemolytic anemia.</p> Signup and view all the answers

What laboratory investigations are essential for diagnosing aplastic anemia?

<p>Essential investigations include complete blood count (CBC), reticulocyte count, bone marrow aspirate, and possibly virology tests to distinguish from similar conditions.</p> Signup and view all the answers

Explain how PNH differs from other causes of bone marrow failure.

<p>PNH is characterized by the deficiency of glycosylphosphatidylinositol (GPI) anchors leading to red cell lysis and is associated with bone marrow hypoplasia, distinct from aplastic anemia.</p> Signup and view all the answers

What is the relationship between aplastic anemia and autoimmune diseases?

<p>Aplastic anemia can occur in association with autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), due to immune-mediated mechanisms.</p> Signup and view all the answers

Discuss the potential genetic factors implicated in aplastic anemia.

<p>Genetic factors may influence the incidence of aplastic anemia, especially related to HLA (II) histocompatibility antigens associated with immune mechanisms.</p> Signup and view all the answers

What is the significance of reticulocyte count in the evaluation of aplastic anemia?

<p>Reticulocyte count is significant as it reflects erythropoietic activity; in aplastic anemia, this count is typically low due to ineffective hematopoiesis.</p> Signup and view all the answers

How can immunosuppressive therapy aid in the management of aplastic anemia?

<p>Immunosuppressive therapy may improve bone marrow function by reducing immune-mediated damage to hematopoietic stem cells in aplastic anemia.</p> Signup and view all the answers

Study Notes

Aplastic Anemia

  • Definition: A bone marrow failure syndrome characterized by peripheral pancytopenia and marrow hypoplasia.
  • Pathogenesis: Involves either a single cell line or all myeloid lineages due to defects in hematopoietic stem cells.
  • Etiologies:
    • Congenital/Inherited (20%):
      • Fanconi anemia (FA): Autosomal recessive, associated with growth retardation, congenital defects, chromosomal breakage.
      • Dyskeratosis congenita (DC): Manifestations include skin abnormalities, nail dystrophy, mucosal lesions.
      • Diamond–Blackfan anaemia (DBA): Pure red cell aplasia, often diagnosed in infancy.
      • Shwachman-Diamond syndrome (SDS): Characterized by pancreatic insufficiency, skeletal abnormalities.
      • Familial aplastic anemia: Family history of aplastic anemia.
      • Severe congenital neutropenia: Marked decrease in neutrophils.
    • Acquired (80%):
      • Primary (Idiopathic): Most common form, likely autoimmune in origin.
      • Secondary (Causes):
        • Ionizing radiation: Accidental or therapeutic (radiotherapy).
        • Drugs:
          • Marrow depressants: Busulfan, melphalan, cyclophosphamide, etc.
          • Occasional/Rare causes: Chloramphenicol, sulphonamides, gold, etc.
        • Chemicals: Benzene, organophosphates, pesticides.
        • Viruses: Hepatitis, EBV, Herpes simplex, Parvovirus.
        • Autoimmune diseases: SLE, RA.
        • Transfusion associated GVHD.
        • Thymoma.
        • Malignancies: AML, ALL, MDS.
        • Pregnancy.
  • Potential Mechanisms:
    • Absent or defective stem cells.
    • Abnormal marrow micro-environment.
    • Inhibition by an abnormal clone of hematopoietic cells.
    • Abnormal regulatory cells or factors.
    • Immune-mediated suppression of hematopoiesis.
  • Genetic predisposition: Higher incidence with HLA (II) histocompatibility Antigen.
  • Immune mechanism: Autoreactive T-cells, intrinsic stem cell defects, and/or immune suppression.
  • Forms:
    • Inevitable: Dose-related, e.g., cytotoxic drugs, ionizing radiation.
    • Idiosyncratic: Unpredictable, e.g., anti-inflammatory antibiotics, anti-epileptic medications.
  • Common Traits:
    • Aplasia from any origin may recover after immunosuppressive therapy, implying immune involvement.
    • Transition to a clonal disorder of hemopoiesis can occur in any patient who has recovered bone marrow function, suggesting hematopoietic system fragility.
  • Clinical Features:
    • Anemia: Pallor, tachycardia, fatigue, dizziness, shortness of breath.
    • Thrombocytopenia: Bruising, bleeding gums, epistaxis, menorrhagia, retinal hemorrhage.
    • Neutropenia: Infections, particularly of the mouth, throat, skin, lungs, and sepsis.
    • Jaundice and hepatitis: In some patients.
    • Lymph nodes, liver, and spleen are not enlarged.
  • Clinical Features (Inherited Marrow Failure Syndromes):
    • Physical stigmata: Skin pigmentation, short stature, microcephaly, hypogonadism, mental retardation, skeletal anomalies.
  • Investigations:
    • Complete Blood Count (CBC): To assess anemia, thrombocytopenia, and neutropenia.
    • Reticulocyte count: To evaluate erythropoiesis.
    • Blood film: To assess red cell morphology and presence of blasts.
    • Liver function tests: To assess potential liver involvement.
    • Virology: To look for viral causes.
    • Bone marrow aspirate & trephine biopsy: To confirm marrow hypoplasia and assess cellularity.
    • Tests to distinguish AA from PNH: Ham's test, CD55,59 assay.
    • Cytogenetic analysis: For congenital types.

Paroxysmal Nocturnal Hemoglobinuria (PNH)

  • Definition: A rare, acquired clonal disorder of marrow stem cells deficient in the glycosylphosphatidylinositol (GPI) anchor.
  • Clinical triad: Chronic intravascular hemolysis, venous thrombosis, and bone marrow failure.
  • Pathogenesis: Lack of DAF (CD55) and MIRL (CD59) renders red cells sensitive to complement-mediated lysis.
  • Diagnosis:
    • Ham's test (acid hemolycin test): Positive result indicates increased RBC fragility.
    • CD55,59 assay using flow cytometry: Shows deficient RBC populations.
  • Treatment: Eculizumab (Soliris).

Lab findings:

  • Anemia with reticulocytopenia
  • Thrombocytopenia
  • Neutropenia
  • Elevated LDH (lactate dehydrogenase)
  • Hypoalbuminemia
  • Increased bilirubin
  • Bone marrow aspiration and biopsy essential

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Description

Explore the key aspects of aplastic anemia, a serious bone marrow failure syndrome characterized by peripheral pancytopenia and marrow hypoplasia. This quiz covers definitions, pathogenesis, and the various congenital and acquired etiologies of the condition.

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