Aplastic anemia

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Aplastic anemia

Hematological system

Hematological system

Hematological system

Hematological system


Aplastic anemia


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Aplastic anemia

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A 13-year-old girl comes to the pediatrician complaining of exertional dyspnea and easy bruising for the last 2 weeks. She had an upper respiratory infection 3 weeks ago. The remainder of the patient’s past medical history is non-contributory. Temperature is 37.2°C (98.9°F), pulse is 72/min, respirations are 14/min, and blood pressure is 116/68 mmHg. Physical exam shows conjunctival pallor, large purple contusions on the legs, and petechiae on the inside of the mouth. The abdominal exam shows a non-tender, non-distended abdomen and no hepatosplenomegaly. Laboratory testing is obtained and reveals the following:  

Which of the following would most likely be seen on microscopic examination of this patient’s bone marrow?

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Aplastic anemia p. 429

in anemia taxonomy p. 425

chloramphenicol p. 189

as drug reaction p. 251

Fanconi anemia p. 718

neutropenia with p. 431

thionamides p. 362


aplastic anemia p. 251, 429

Café-au-lait spots

aplastic anemia and p. 429


aplastic anemia p. 251

Chloramphenicol p. 189

aplastic anemia and p. 251, 429

Epstein-Barr virus (EBV) p. 162

aplastic anemia p. 429

Erythropoietin (EPO)

aplastic anemia p. 429


aplastic anemia and p. 429

Hepatitis viruses p. 170

aplastic anemia p. 429

HIV (human immunodeficiency virus) p. 172

aplastic anemia in p. 429


for aplastic anemia p. 429

Leukemias p. 440

aplastic anemia and p. 417

Methimazole p. 362

aplastic anemia p. 251

Nonsteroidal anti-inflammatory drugs (NSAIDs) p. 499

aplastic anemia p. 251

Pallor in aplastic anemia p. 429

Parvovirus B16

aplastic anemia p. 417


aplastic anemia as cause p. 429


aplastic anemia p. 251


aplastic anemia p. 429

Radiation exposure

aplastic anemia p. 431

Reticulocytes p. 415

in aplastic anemia p. 429

Stem cells

in aplastic anemia p. 429


Aplastic anemia is a pancytopenia, meaning all blood cell lines are decreased - so the term aplastic anemia, which just refers to low red blood cell count, is actually a misnomer.

So with aplastic anemia, there’s actually anemia, as well as leukocytopenia, or low white blood cells, as well as thrombocytopenia, or low platelet levels.

This condition takes many forms, ranging from mild to severe depending on the cause.

Now, blood cells are produced in the bones of the body, mainly in the bones of the pelvis, ribs and sternum, through a process called hematopoiesis.

This process starts in the bone marrow, the innermost portion of bone, where the hematopoietic stem cells reside.

These serve as progenitor cells for all the different cell types found in the blood.

First, hematopoietic stem cells, also called hemocytoblasts, can become lymphoid progenitors or myeloid progenitors.

The lymphoid progenitors can develop into lymphoblasts, which can then differentiate into some white blood cells like T-lymphocytes, B-lymphocytes, or natural killer cells.

The myeloid progenitors can differentiate into erythrocytes, or red blood cells, megakaryocytes, which eventually give rise to platelets, or myeloblasts, which can then become other white blood cells like monocytes, neutrophils, basophils, and eosinophils.

The most common cause of aplastic anemia is autoimmune destruction of hematopoietic stem cells.

The details of this mechanism are not fully understood, but research shows that there are alterations in the immunologic appearance of hematopoietic stem cells because of genetic disorders, or after exposure to environmental agents, like radiation or toxins.

This means that the hematopoietic stem cells start expressing non-self antigens and the immune system subsequently targets them for destruction.


Aplastic anemia is a rare blood disorder caused by bone marrow failure to produce new blood cells. Even though it's referred to as aplastic anemia, it typically presents with pancytopenia, meaning that all three major blood cell lines - the red blood cells, white blood cells, and platelets are affected.

People with aplastic anemia may experience fatigue, shortness of breath, ecchymoses and mucosal bleeding, and frequent infections pallor Aplastic anemia can be caused by a variety of factors, including exposure to radiation or chemotherapy, viral infections, and autoimmune disorders.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  3. "Current concepts in the pathophysiology and treatment of aplastic anemia" Hematology (2013)
  4. "Aplastic anaemia" Hematology (2013)
  5. "Aplastic Anemia" New England Journal of Medicine (2018)
  6. "Harrison's Principles of Internal Medicine" McGraw-Hill (2004)
  7. "The complex pathophysiology of acquired aplastic anaemia" Clinical & Experimental Immunology (2015)

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