extramedullary hematopoiesis
Pronunciation: extra-MED-yoo-lar-ee hee-mat-oh-poy-EE-sis
Also written as: EMH
Blood cell production outside bone marrow, occurring in myelofibrosis and other conditions. Compensatory mechanism for marrow dysfunction.
Full Definition
Extramedullary hematopoiesis refers to the production of blood cells in organs outside the bone marrow, most commonly the spleen and liver, though it can occur in other tissues. This process represents the body's attempt to compensate for inadequate bone marrow function, as seen in myelofibrosis, severe anemia, or bone marrow infiltration by malignancy. In adults, extramedullary hematopoiesis is always pathological and can lead to organomegaly, mass lesions, or cytopenias due to ineffective blood cell production. Recognition of this process is important for understanding disease pathophysiology and potential complications in hematologic disorders.
Usage
Usage note: Hyphenate extramedullary when used as a compound modifier. Can be abbreviated as EMH in appropriate contexts.
In Context
- "CT imaging revealed extramedullary hematopoiesis in the paraspinal region." — Radiology report
- "The massive splenomegaly was attributed to extramedullary hematopoiesis." — Clinical assessment