Extramedullary hematopoiesis

Dr Daniel J Bell and Radswiki et al.

Extramedullary hematopoiesis is a response to the failure of erythropoiesis in the bone marrow.

This article aims to a general approach on the condition, for a dedicated discussion for a particularly involved organ, please refer to the specific articles on: 



Radiographic features

When involving an organ, extramedullary hematopoiesis causes visceromegaly occurring most often in the spleen (splenomegaly) and liver (hepatomegaly) and occasionally in the lymph nodes. Visceromegaly is best evaluated with ultrasound, CT or MRI.  Lesions are typically hypermetabolic and are FDG-18 avid on PET-CT 4.

Extramedullary hematopoiesis less commonly affects the pleura, lungs, gastrointestinal tract, breast, skin, brain, kidneys, and adrenal glands.

However, in the less common situation where extramedullary hematopoiesis involves other tissues within the thorax, they can be seen as a posterior mediastinal mass. These paraspinal masses may be either unilateral or bilateral and have smooth, sharply-delineated, often lobulated margins.

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Article information

rID: 12220
Synonyms or Alternate Spellings:
  • Extramedullary hematopoiesis
  • Extra-medullary haematopoiesis (EMH)
  • Extra-medullary haematopoiesis
  • Extramedullary haematopoiesis (EMH)
  • Extramedullary haemopoiesis
  • Extramedullary hemopoiesis

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Cases and figures

  • Case 1: in thalassemia
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  • Case 1: in thalassemia
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  • Case 2: in thalassemia
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  • CXR - PA
    Case 3: in thalassemia
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  • Case 4
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  • Case 5
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  • Case 6
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  • Case 7: in the adrenal gland
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