Extramedullary hematopoiesis

Micrograph showing nucleated red blood cells (bottom left of image), one of the elements necessary to call extramedullary hematopoiesis, in an endometrial polyp. H&E stain.

Extramedullary hematopoiesis (EMH or sometimes EH[1]) refers to hematopoiesis occurring outside of the medulla of the bone (bone marrow).[2] It can be physiologic or pathologic.

Physiologic EMH occurs during embryonic and fetal development; during this time the main site of fetal hematopoiesis are liver and the spleen.

Pathologic EMH can occur during adulthood when physiologic hematopoiesis can't work properly in the bone marrow and the hematopoietic stem cells (HSC) have to migrate to other tissues in order to continue with the formation of blood cellular components. Pathologic EMH can be caused by myelofibrosis,[3] thalassemias or disorders caused in the hematopoietic system.

  1. ^ Kim CH (2010-03-23). "Homeostatic and pathogenic extramedullary hematopoiesis". Journal of Blood Medicine. 1: 13–9. doi:10.2147/jbm.s7224. PMC 3262334. PMID 22282679.
  2. ^ Birbrair A, Frenette PS (April 2016). "Niche heterogeneity in the bone marrow". Annals of the New York Academy of Sciences. 1370 (1): 82–96. Bibcode:2016NYASA1370...82B. doi:10.1111/nyas.13016. PMC 4938003. PMID 27015419.
  3. ^ Chunduri S, Gaitonde S, Ciurea SO, Hoffman R, Rondelli D (October 2008). "Pulmonary extramedullary hematopoiesis in patients with myelofibrosis undergoing allogeneic stem cell transplantation". Haematologica. 93 (10): 1593–5. doi:10.3324/haematol.13203. PMID 18641018.