Lymph Node - Extramedullary Hematopoiesis

comment:
While the bone marrow is the major site of hematopoiesis, lymph nodes may be a site of extramedullary hematopoiesis (EMH). EMH in lymph nodes typically occurs as a physiologic response to a dramatic loss or increased need for additional blood cells. Examples of inciting factors include hemorrhage, infection, severe inflammation, myelofibrosis, and neoplasia. EMH is characterized by a mixture, to varying degrees, of myeloid, erythroid, and megakaryocytic cells and is primarily present within the lymph node medullary cords ( Figure 1

recommendation:
Extramedullary hematopoiesis in lymph nodes should be diagnosed and graded. The presence of this lesion in lymph nodes should prompt evaluation of other organs for EMH (especially the spleen and liver).related links:
Liver - Extramedullary HematopoiesisLymph Node - Inflammation
Spleen - Extramedullary Hematopoiesis
references:
Dunn TB. 1954. Normal and pathologic anatomy of the reticular tissue in laboratory mice. J Nat Cancer Inst 14:1281-1433. Abstract: http://jnci.oxfordjournals.org/content/14/6/1281.extract
Elmore SA. 2006. Histopathology of the lymph nodes. Toxicol Pathol 34:425-454. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1892634/
Elmore SA. 2006. Enhanced histopathology of the lymph nodes. Toxicol Pathol 34:634-647. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1783683/
Kim CH. 2010. Homeostatic and pathogenic extramedullary hematopoiesis. J Blood Med 1:13-19. Full Text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3262334/
National Toxicology Program. 2011. NTP TR-570. Toxicology and Carcinogenesis Studies of α,β-Thujone (CAS No. 76231-76-0) in F344/N Rats and B6C3F1 Mice (Gavage Studies). NTP, Research Triangle Park, NC. Abstract: https://ntp.niehs.nih.gov/go/36137
Web page last updated on: January 28, 2015