Extramedullary haematopoiesis

Dr Mostafa El-Feky and Radswiki et al.

Extramedullary haematopoiesis 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: 

Extramedullary haematopoiesis usually affects visceral organs like liver, spleen, lymph nodes and involves thorax. Less commonly it can affect the pleura, lungs, gastrointestinal tract, breast, skin, brain, kidneys, and adrenal glands.

  • most common: diffuse visceromegaly (splenomegaly and hepatomegaly)
    • best evaluated with ultrasound, CT or MRI
    • lesions are typically hypermetabolic, hence FDG-18 PET avid 4
  • rarely, can result in focal masses in liver and spleen that need to be differentiated from malignancy
  • most common intrathoracic finding is a posterior mediastinal mass
    • may be either unilateral or bilateral
    • smooth, sharply-delineated, often lobulated margins
    • fat can be seen, if chronic
    • calcification is very atypical
  • other than this, within the thorax, there can be rib expansion and rarely pulmonary infiltrates 4
  • perirenal soft tissue with normal renal contour can be seen (mimicking lymphoma or Erdheim-Chester disease like appearance) 4. It has been found to be the most common retroperitoneal finding 4
  • focal or diffuse peritoneal nodules can be seen 4
  • can present as pre-sacral soft tissue mass 4
  • epidural soft tissue masses with peripheral fat can be seen in spinal cord or CNS with compression of spinal cord 4

These masses are generally hypervascular with high chances of occurrence of bleeding as a complication of biopsy. Hence, avoid biopsy near vital structures like spinal cord to avoid risk of spinal cord compression. FNAC is a better option at such sites 4. For treatment, giving radiotherapy on the involved site or excision of the mass or multiple blood transfusions to decrease extramedullary haematopoiesis can be done 4.

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 thalassaemia
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  • Case 1: in thalassaemia
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  • Case 2: in thalassaemia
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  • Case 3: in thalassaemia
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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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  • Case 8
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  • Case 9: peritoneal
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  • Case 10
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  • Case 11 : MRI
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  • Case 12: thalassaemia
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  • Case 13
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