Pros and cons of splenectomy in patients with myelofibrosis undergoing stem cell transplantation.

During fetal development, the spleen is a major hemopoietic organ. In the adult human, this task is relinquished to the bone marrow. However, under the stress of certain pathologic conditions, extramedullary hemopoiesis may again occur in the spleen. This is especially true for diseases of the marrow, in particular, myeloproliferative disorders such as agnogenic myeloid metaplasia, which is associated with severe fibrosis of the marrow space. At the same time, the spleen sequesters blood cells and contributes to peripheral blood cytopenias, which may improve following splenectomy. However, success is unpredictable, and the operative mortality of splenectomy is on the order of 10%. As a growing number of patients undergo hemopoietic stem cell transplantation as definitive therapy for myelofibrosis, the decision on splenectomy has additional ramifications since the spleen plays an important role in the kinetics of engraftment of donor cells and in immune reconstitution. We conclude from our analysis of available information that the benefit of splenectomy is difficult to predict, although after transplantation splenectomized patients have faster hemopoietic recovery. It appears that the most important indication for splenectomy in these patients is the relief of symptoms from massive spleen enlargement.