Extramedullary hematopoiesis in myeloproliferative neoplasms: Pathophysiology and treatment strategies

Extramedullary hematopoiesis (EMH) is often a physiologic response to ineffective marrow production of hematologic cells. While this can be found incidentally in various physiologic and pathophysiologic states, the myeloproliferative neoplasms (MPNs) are some of the most common underlying conditions found in patients with EMH. Although this process can assist with hematologic production in defective states, the burden of EMH can lead to symptomatic discomfort and mechanical obstructive complications, most commonly in the spleen and liver. Here we describe the pathophysiology of EMH, treatment options, including medical, surgical and radiation-based approaches.