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:
Extramedullary hematopoiesis 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.
- myeloproliferative disorders
- 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 occurence of bleeding as a complication of biopsy. Hence, avoid biospy 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 hematopoiesis can be done 4.
- 1. Choi H, David CL, Katz RL et-al. Case 69: extramedullary hematopoiesis. Radiology. 2004;231 (1): 52-6. doi:10.1148/radiol.2311020673 - Pubmed citation
- 2. Gumbs RV, Higginbotham-ford EA, Teal JS et-al. Thoracic extramedullary hematopoiesis in sickle-cell disease. AJR Am J Roentgenol. 1987;149 (5): 889-93. AJR Am J Roentgenol (abstract) - Pubmed citation
- 3. Holden C, Hennessy O, Lee WK. Diffuse mesenteric extramedullary hematopoiesis with ascites: sonography, CT, and MRI findings. AJR Am J Roentgenol. 2006;186 (2): 507-9. doi:10.2214/AJR.04.1788 - Pubmed citation
- 4. Roberts AS, Shetty AS, Mellnick VM, Pickhardt PJ, Bhalla S, Menias CO. Extramedullary haematopoiesis: radiological imaging features. Clinical radiology. 71 (9): 807-14. doi:10.1016/j.crad.2016.05.014 - Pubmed
- 5. Granjo E, Bauerle R, Sampaio R, Manata P, Torres N, Quintanilha A. Extramedullary hematopoiesis in hereditary spherocytosis deficient in ankyrin: a case report. (2002) International journal of hematology. 76 (2): 153-6. Pubmed
- 6. Wolfgang Dähnert. Radiology Review Manual. (2011) ISBN: 9781609139438