5.3: Aplastic Anemia

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Bone Marrow Failure:

Bone marrow failure is characterized by reduced hematopoiesis in the bone marrow resulting in cytopenias in one or more cell lines. Decreased hematopoiesis can be attributed to:¹

Destruction of hematopoietic stem cells due to acquired causes
Destruction of hematopoietic stems cells due to inherited causes
Ineffective erythropoiesis
Disruption of bone marrow microenvironment
Reduced production of growth factors and hormones related to hematopoiesis
Infiltration of the bone marrow

Aplastic anemia is a bone marrow failure syndrome that is characterized by a decreased cell count in all cell lines (pancytopenia) and a hypocellular (aplastic) bone marrow. (McKenzie ch 16 pg 303, Rodak ch 22 pg 332) Unlike other anemias, hepatosplenomegaly and lymphadenopathy are absent. (McKenzie ch 16 pg 307)

Cause(s):

There is no known, single cause of aplastic anemia but it’s development can be associated with a variety of clinical states and agents which can be either acquired or inherited.^1,2 It is thought that acquired causes of aplastic anemia can lead to an immunologic response against one’s own hematopoietic stem cells.¹

Table 1. List of acquired and inherited causes of aplastic anemia.^1-3

Acquired:

Idiopathic

Drugs and Chemicals

Radiation

Infectious agents

Clonal Disorders (e.g. MDS, PNH)

Inherited:

Fanconi Anemia (autosomal recessive, rare X-linked recessive)

Dyskeratosis congenita

Shwachman-Diamond Syndrome

Laboratory Features of Aplastic Anemia:^1,3

CBC:

RBC: Decreased

WBC: Decreased

PLT: Decreased

Hb: Decreased

RETIC: Decreased

MCV: Normal to increased

PBS:

Pancytopenia

(Thrombocytopenia, neutropenia, anemia)

Normochromic

Normocytic or macrocytic

BM:

Hypocellular or dry tap

Fatty infiltration

Iron Studies:

Serum Iron: Increased

Ferritin: Increased

Transferrin: Normal

Transferrin Saturation: Normal to increased

Other Tests:

Molecular testing

Flow cytometry

References:

1. Lo C, Glader B, Sakamoto KM. Bone marrow failure. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 331-47.

2. Laudicina R. Hypoproliferative anemias. In: Clinical laboratory hematology. 3rd ed. New Jersey: Pearson; 2015. p. 302-16.

3. Perkins SL. Aplastic anemia including pure red cell aplasia, congenital dyserythropoietic anemia, and paroxysmal nocturnal hemoglobinuria. In: Clinical hematology and fundamentals of hemostasis. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 156-75.