Aplastic anemia Flashcards
definition
🧩Aplastic anemia is a physiologic and anatomic failure of the bone marrow characterized by a marked decrease or absence of blood-forming elements in the marrow and peripheral pancytopenia.
🧩Splenomegaly, hepatomegaly, and lymphadenopathy are not characteristic of this condition.
🧩It may be congenital or acquired.
Fanconi anemia
⭕️Congenital aplastic anemias
⭕️Fanconi anemia (FA) is a rare autosomal recessive inherited bone marrow failure syndrome generally associated with multiple congenital anomalies.
⭕️The median age at hematologic presentation of patients is approximately 7 years. Bone marrow failure is virtually occurring in 90% by 40 years of age.
⭕️Hematologic dysfunction usually presents with macrocytosis, followed by thrombocytopenia, often leading to progressive pancytopenia and severe aplastic anemia (SAA).
⭕️FA frequently terminates in myelodysplastic syndrome (MDS) and/or AML.
Diagnosis (fanconi anemia)
🔴chromosome breakage test: FA cells are hypersensitive to chromosomal breaks induced by DNA cross linking agents (clastogens); diepoxybutane (DEB) and mitomycin C (MMC) are the agents most frequently used in vitro to induce chromosome breaks, and other structural abnormalities.
🔴Bone marrow examination reveals: ➰hypocellularity
➰and fatty replacement consistent with the degree of peripheral pancytopenia.
▪️Residual hematopoiesis may reveal ➰dysplastic erythroid (megaloblastoid changes, multinuclearity)
➰and myeloid (abnormal granulation) precursors
➰and abnormal megakaryocytes.
🔴additional studies
🔹Endocrine studies
🔹Radiological Imaging and ultrasonography
🔹echocardiography
🔹Family survey for Fanconi anemia
🔹HLA matching of the patient and family member
Associated congenital anomalies (fanconi anemia)
➰ increased pigmentation of the skin along with café au lait and hypopigmented areas
➰short stature (impaired growth hormone secretion),
➰skeletal anomalies (especially involving the thumb, radius, and long bones),
➰male hypogenitalism,
➰microcephaly
➰abnormalities of the eyes (e.g., microphthalmia, ptosis) and ears including deafness.
➰developmental delay
➰renal and cardiac anomalies.
Management (fanconi anemia)
● Androgen (oxymetholone) and cytokine therapy (granulocyte colony-stimulating factor [G-CSF] or granulocyte-macrophage colony-stimulating factor [GM-CSF]) should be administered when moderate to severe cytopenia is present.
● Supportive transfusions: Blood products should be irradiated, leukocyte depleted, and of single donor origin.
Blood relatives should not be used as blood donors until a matched allogeneic related donor transplant is ruled out.
●***Allogeneic hematopoietic stem cell transplantation: HLA typing should be done at diagnosis. The donor should be evaluated to exclude a diagnosis of Fanconi anemia.
Causes of acquired aplastic anemia
1️⃣ Idiopathic (70% or more of cases)
2️⃣ Secondary
🔹Drugs:
〰️Predictable, dose dependent, rapidly reversible (chemotherapy, chloramphenicol).
〰️Unpredictable: Antibiotics (chloramphenicol, sulfonamides), anticonvulsants (mephenytoin), antirheumatics (gold), antidiabetics (chlorpropamide), antimalarial (quinacrine).
🔹Chemicals: insecticides (e.g., DDT, Parathion, Chlordane).
🔹Toxins (e.g., benzene, carbon tetrachloride, glue, toluene).
🔹Irradiation
🔹Infections: viral hepatitis, HIV infection, EBV, rubella, influenza, parainfluenza…etc.
🔹Aplastic anemia preceding acute leukemia (hypoplastic preleukemia)
🔹Myelodysplastic syndromes, thymoma, paroxysmal nocturnal hemoglobinuria
🔹Malnutrition, kwashiorkor, marasmus, anorexia nervosa
🔹Pregnancy
Severity of fanconi anemia
⭕️Mild aplastic anemia
bone marrow cellularity of more than 50%
➕ granulocyte count, > 1,000/mm3, or platelet count, >50,000/mm.
⭕️Moderate aplastic anemia
bone marrow cellularity of more than 20-50%
➕ granulocyte count, > 500-1,000/mm3, or platelet count, 20,000-50,000/mm3.
⭕️Severe aplastic anemia
bone marrow cellularity of less than 25%
➕ granulocyte count, <500/mm3 (<200/mm3 in very severe aplastic anemia), or platelet count, <20,000/mm.
Treatment of fanconi anemia
🔮 mild to moderate aplastic anemia ➡️should be observed for spontaneous improvement or complete resolution.
🔮 severe ➡️ The treatment of choice for SAA
➰hematopoietic stem cell transplantation
➰In the absence of an HLA-matched sibling marrow donor treat the patient with ATG, cyclosporine A (CSA), methylprednisolone, and growth factors such as G-CSF or GM-CSF.
cardinal features (Hemolytic Anemias)
pallor
jaundice
with or without splenomegaly
Lab features(hemolytic anemia)
anemia
reticulocytosis
indirect hyperbilirubinemia
Suggestive Features (hemolytic anemia)
⭕️Ethnic factors: High incidence of sickle cell disease in the south of Iraq, thalassemia trait in Mediterranean people
⭕️History of anemia, jaundice, or gallstones in family
⭕️Intermittent bouts or persistent indirect hyperbilirubinemia/jaundice
⭕️Dark color urine and hemoglobinuria
⭕️Presence of multiple gallstones
⭕️Development of anemia or hemoglobinuria after exposure to certain drugs
Extravascular vs Intravascular hemolysis
🟢 Markers of Extravascular Hemolysis
1. Increased unconjugated bilirubin.
2. Increased lactic acid dehydrogenase in serum.
3. Decreased plasma haptoglobin.
4. Increased fecal and urinary urobilinogen.
🟢Markers of Intravascular Hemolysis
1. Increased unconjugated bilirubin.
2. Increased lactic acid dehydrogenase in serum.
3. Hemoglobinuria.
4. Low or absent plasma haptoglobin.
Classification of Hemolytic Anemia
🔹I. Inherited disorders
1. RBC membrane defect: Hereditary spherocytosis
2. Enzyme defect: G6PD deficiency
3. Hemoglobin defects: Thalassemia
🔹II. Acquired disorders
1. Immune mediated; i. Autoimmune (autoimmune hemolytic anemia), ii. Alloimmune (hemolytic transfusion reaction)
2. Non-immune: valve prosthesis, microangiopathy.
Normal Hemoglobins
🔴Hemoglobin A: It is the designation for the normal hemoglobin that exists after birth. Hemoglobin A is a tetramer with two alpha chains and two beta chains (2
🔴Hemoglobin A2: It is a minor component of thehemoglobin after birth; it consists of two alpha chains and two delta chains (22). Hemoglobin A2 generally comprises 2-3.4% of the total red cell hemoglobin
🔴 Hemoglobin F: It is the predominant hemoglobin during fetal development. The molecule is a tetramer of two alpha chains and two gamma chains (22).
Hb according to age
🔺After the 8th gestational wk Hb F is the predominant Hb
🔺 At 24 wk gestation Hb F constitutes 90% of the total Hb 5-10% of Hb A is present
🔺During the 3rd trimester there is a gradual decline of Hb F
🔺At birth Hb F averages 70% of the total; Hb A averages 30%.
🔺By 6-12 mo of age less than 2% of Hb F can be detected; Hb A predominates