This document summarizes aplastic and hypoplastic anemias. Aplastic anemia is a life-threatening condition where the bone marrow fails to produce red blood cells, white blood cells, and platelets, leading to pancytopenia. It can be acquired through exposure to radiation, chemicals, infections or idiopathically. Congenital causes include Fanconi's anemia and familial aplastic anemia. Clinical manifestations include fatigue, pallor, infections, and bleeding. Treatment involves removing causative agents if known, blood transfusions, and bone marrow transplant. Related disorders with pancytopenia include myelodysplastic syndromes and pure red cell aplasia.

1. APLASTIC AND
HYPOPLASTIC
ANEMIAS

2. WHAT HAPPENS WHEN
THE BONE MARROW
SHUTS DOWN?

3. Aplastic anemia
 Aplastic anemia is a severe, life threatening syndrome in
which production of erythrocytes, WBCs, and platelets
has failed.
 Aplastic anemia may occur in all age groups and both
genders.
 The disease is characterized by peripheral
pancytopenia and accompanied by a hypocellular
bone marrow.

4. Hypocellular bone marrow in
aplastic anemia

5. Aplastic anemia
 PATHOPHYSIOLOGY:
 The primary defect is a reduction in or depletion
of hematopoietic precursor stem cells with
decreased production of all cell lines. This is what
leads to the peripheral pancytopenia.

6.  This may be due to quantitative or qualitative damage
to the pluripotential stem cell.
 In rare instances it is the result of
1. Abnormal hormonal stimulation of stem cell
proliferation or
2. The result of a defective bone marrow
microenvironment or
3. From cellular or humoral immunosuppression of
hematopoiesis.

7. ETIOLOGY
ACQUIRED
CONGENITAL

8. Aplastic anemia
ACQUIRED
 Most cases of aplastic anemia are idiopathic and
there is no history of exposure to substances known
to be causative agents of the disease
 Exposure to ionizing radiation – hematopoietic
cells are especially susceptible to ionizing radiation.
Whole body radiation of 300-500 rads can
completely wipe out the bone marrow. With
sublethal doses, the bone marrow eventually
recovers.
 Chemical agents – include chemical agents with a
benzene ring, chemotherapeutic agents, and certain
insecticides.
 Idiosyncratic reactions to some commonly used
drugs such as chloramphenicol or quinacrine.

9. Aplastic anemia
 Infections – viral and bacterial infections such as
infectious mononucleosis, infectious hepatitis,
cytomegalovirus infections, and miliary
tuberculosis occasionally lead to aplastic anemia
 Pregnancy (rare)
 Paroxysmal nocturnal hemoglobinuria – this is
a stem cell disease in which the membranes of
RBCs, WBCs and platlets have an abnormality
making them susceptible to complement mediated
lysis.
 Other diseases – preleukemia and carcinoma

10. Aplastic anemia
 CONGENITAL DISORDERS
 Fanconi’s anemia – the disorder usually
becomes symptomatic ~ 5 years of age and is
associated with progressive bone marrow
hypoplasia. Congenital defects such as skin
hyperpigmentation and small stature are also seen
in affected individuals.
 Familial aplastic anemia – a subset of Fanconi’s
anemia in which the congenital defects are absent.

11. ETIOLOGY
ACQUIRED CONGENITAL
1. Idiopathic
2. Ionizing radiation
3. Chemical agents
4. Idiosynratic reactions
5. Infections
6. Pregnancy
7. PNH
8. others
1. Fanconi,s
anemia
2. Familial aplastic
anemia

12. CLINICAL MANIFESTATIONS
 Fatigue
 Heart palpitations
 Pallor
 Infections
 Petechiae
 Mucosal bleeding

13. Aplastic anemia
 LAB FINDINGS
 Severe pancytopenia with relative lymphocytosis
(lymphocytes live a long time)
 Normochromic, normocytic RBCs (may be
slightly macrocytic)
 Mild to moderate anisocytosis and poikilocytosis
 Decreased reticulocyte count
 Hypocellular bone marrow with > 70% yellow
marrow

14. TREATMENT
 in untreated cases the prognosis is poor
 Remove causative agent, if known
 Multiple transfusions
 Bone marrow transplant

15. Related disorders
 Disorders in which there is peripheral
pancytopenia, but the bone marrow is
normocellular, hypercellular, or infiltrated with
abnormal cellular elements
 Myelopthesic anemia – replacement of bone
marrow by fibrotic, granulomatous, or neoplastic
cells

16. Related disorders
 MYELODYSPLASTIC SYNDROMES – are primary,
neoplastic stem cell disorders that tend to terminate in acute
leukemia.
 The bone marrow is usually normocellular, or hypercellular
with evidence of qualitative abnormalities in one or more cell
lines resulting on ineffective erythropoiesis and/or
granulopoiesis and/or megakaryopoiesis.
 The peripheral smear shows dysplastic (abnormality in
development) cells including nucleated RBCs, oval
macrocytes, pseudo-Pelger-Huet PMNs (hyposegmented
neutrophils) with hyperchromatin clumping, hypogranulated
neutrophils, and giant bizarre platlets.
 HYPERSPLENISM – why can this lead to pancytopenia?

17. Pure Red Cell Aplasia
 Pure red cell aplasia is characterized by a selective
decrease in erythroid precursor cells in the bone
marrow. WBCs and platlets are unaffected.
 ACQUIRED
 Transitory with viral or bacterial infections
 Patients with hemolytic anemias may suddenly halt
erythropoiesis
 Patients with thymoma – T-cell mediated responses
against bone marrow erythroblasts or erythropoietin are
sometimes produced.

18. Pure Red Cell Aplasia
 CONGENITAL
 Diamond-Blackfan syndrome – occurs in young
children and is progressive. It is probably due to an
intrinsic or regulatory defect in the committed erythroid
stem cell.

19. OTHER HYPOPROLIFERATIVE
ANEMIAS
 Renal disease – due to decreased erythropoietin
 Endocrine deficiencies – may lead to decreased
erythropoietin production. For example:
hypothyroidism leads to decreased demand for
oxygen from tissues; decreased androgens in
males; decreased pituitary function

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