Sentence:  <WSD>Extramedullary</WSD> hematopoiesis (EMH) is a rare disorder, defined as the appearance of hematopoietic elements outside the bone marrow or peripheral blood. The most common sites of EMH are liver and spleen, but it has been documented in other organs such as the mediastinum, lymph nodes, breast, and central nervous system. EMH occurs as a compensatory mechanism for bone marrow dysfunction in severe thalassemia. 
Meaning of the word marked with <WSD> tags:  Outside of the bone marrow, as with extramedullary hematopoiesis.