Invited Commentary Indications for Splenectomy STEVEN C. KATZ, M.D., H. LEON PACHTER, M.D. From the Department of Surgery, New York University Medical Center and Bellevue Hospital Center, Nezv York, NY In the new millennium, indications for splenectomy have expanded. Proper patient selection based on an understanding of the biology of each individual's disease is essential for a favorable outcome. We review the most common diseases for which surgeons may be called on to perform splenectomy and while highlighting potential pitfalls and caveats. HE SPLEEN MEDITATES important immunologic and Development and Anatomy hematologic functions as well as contributing to T The spleen forms as a mesenchymal condensation numerous pathologic processes. When the spleen is of the dorsal mesogastrium during the fifth week of involved in disease, splenectomy may be performed development. Initially, the spleen functions as a he- with tbe intent of either altering tbe clinical course or matopoietic organ and assumes its more mature lym- providing symptomatic relief. In the new millennium, phoid characteristics at 15 to 18 weeks.^ The spleen is indications for splenectomy have expanded, and sple- related to the posterior wall of the stomach and is nectomy may be beneficial to patients with a broad connected to the stomach and kidney by the gastro- spectium of benign and malignant diseases. Proper splenic and splenorena! ligaments. With the exception patient selection based on an understanding of the bi- of the hilum. the spleen is surrounded by peritoneum. ology of each individual's disease is essential for a On average, tbe spleen is 12 cm long and 7 cm wide. favorable outcome. The splenic artery originates from the celiac axis and Splenectomy is not without potential complications, divides into 5 or more terminal branches that enter the the most feared of which being overwhelming post- splenic hilum. Several tributaries join to form the splenectomy infection (OPSI). Mortality rates of OPSI splenic vein, which joins the superior mesenteric vein may exceed 50 per cent in unvaccinated patients.' to form the portal vein posterior to the neck of the Therefore, removal of the spleen should be performed pancreas. only when the potential benefits to the patient clearly exceed the risks. Recent advances in surgical tech- A dense fibrous capsule surrounds the spleen and niques allow for a laparoscopic approach in many pa- trabeculae form incomplete parenchymal compart- tients who require splenectomy, thereby minimizing ments within the splenic pulp. Stretching of the cap- operative morbidity and patient discomfort associated sule may cause pain in patients witb splenomegaly. On with open splenectomy. However, a minimally inva- cross-section, the spleen contains both red and white sive approach lo splenectomy is not always feasible or pulp. Arteries within the white pulp, central arteries, desirable and therefore familiarity with the traditional are surrounded by a sheath of lymphocytes known as approach remains vital. We review the spectrum of the periarteriolar lymphatic sheatb (PALS).^ Tbe disease processes for which splenectomy may be in- PALS is comprised primarily of T ceils, whereas ad- dicated. Prerequisites for successful therapeutic or pal- jacent lymphoid follicles are abundant in B cells. The liative splenectomy are a thorough understanding of marginal zone lies between tbe white and red pulp splenic anatomy, physiology, and pathophysiology. containing dendritic cells, which capture and present We discuss the most common diseases for which sur- antigen to lymphocytes. Within the red pulp, the sinu- geons may be called on to perform splenectomy and soids are lined by a fenestrated endothelium similar to consider tbe various surgical approaches while high- the lumen of the hepatic sinusoids."^ lighting potential pitfalls and caveats. Normal Splenic Function Although many functions of the spleen are redun- Address correspondence and reprint requests to H. Leon Pachter. M.D.. HCC 6 6C, 550 First Avenue, New York. NY dant or can be assumed by other organs, splenectomy 10016. can lead to adverse consequences. An appreciation of 565 566 THE AMERICAN SURGEON July 2006 Vol. 72 normal spleen function is important for the physician adults often require specific therapeutic intervention. seeking to understand the potential consequences of In the event of persistent or recurrent disease after splenectomy in a given disease process. Under normal treatment with glucocorticoids. cytotoxic agents, or conditions, the spleen contains less than 50 mL of immunoglobulin. patients with ITP may benefit from blood and does not serve as a depot for intravascular splenectomy. Demonstration ot megakaryocytes in the volume, platelets, leukocytes, or erythrocytes. In the bone marrow and the absence of splenomegaly are setting of splenomegaly or portal hypertension, the essential for establishing the diagnosis of ITP before storage volume of the spleen expands and formed el- splenectomy is undertaken. Musser reported that after ements of Ihe blood are .sequestered."^ As much as one splenectomy for ITP, up to 77 per cent of patients third of the total platelet mass may be stored in the show a complete response. In addition, 14 per cent of spleen and released during inHammatory states/' patients show a partial response, whereas only 9 per Although active hematopoiesis occurs in the fetal cent failed to demonstrate a significant improvement spleen, it does not normally occur in postnatal life. in platelet count.'"^ Unfortunately, preoperative char- However, in certain pathologic states such as myelo- acteristics do not necessarily predict which patients fibrosis, extramedullary hematopoiesis may indeed with ITP will respond to splenectomy.''^ Failure of take place within the spleen. The splenic white pulp is splenectomy to improve the thrombocytopenia may bo the largest accumulation of lymphoid tissue in the the result of an unappreciated accessory spleen or in body and is a site of lymphocyte production and acti- traabdominal implantation of splenic tissue should vation, from which cells migrate into the red pulp to fragmentation occur during surgery or extraction alter reach the lumen of the splenic sinusoids. Dendritic a iaparo.scopic approach. Particular attention should be cells and macrophages in the marginal zone are in- paid to the latter, especially during the "morseli/ation" volved with antigen trapping, processing, and presen- process used to facilitate removal while limiting iho tation. Splenic macrophages are particularly adept at size of the incision. recognizing and clearing opsonized bacteria.^ Both Similarly, autoimmune hemolytic anemia may re- dendritic cells^ and T lymphocytes" within the spleen sult in the need for splenectomy if the patient fails to appear to have potent immunologic function. respond to medical management, including oral corti- In addition to its role in the immune system, the costeroids.""' Like with ITP, the pathogenesis of atito- spleen is the site of senescent erythrocyte destruction. immune hemolysis involves antibody-mediated cellu- Macrophages in the splenic cords phagocytose eryth- lar destruction and complement activation within the rocytes and metabolize hemoglobin. Aged erythro- splenic substance. In patients with warm-reacting an- cytes are more sensitive to the relatively acidotic. hyp- tibodies, favorable responses to spienectomy can be oxic, and hypoglycemic milieu of the spleen. The expected in 50 per cent to 80 per cent.'^ heightened sensitivity of senescent erythrocytes to the hostile splenic environment leads to alterations in Felty 's Syndrome membrane carbohydrate moieties.'" thereby facilitat- ing recognition by macrophages and subsequent cull- Felty's syndrome is the occurrence of neutropenia ing or destruction of damaged cells. In addition to and splenomegaly in patients with rheumatoid arthritis culling, pitting leads to removal of intracellular inclu- (RA). These manifestations are present in less than I sions from erythrocytes. The loss of pitting after sple- per cent of patients with RA. Patients with Felty's nectomy accounts for the appearance of particulate syndrome face an increased risk of infection as a result matter such as Howell-Jolly bodies within erythro- of granulocytopenia. which results, in part, from in- cytes postoperatively. Furthermore, asplenia limits trasplenic destruction of granulocytes.'^ Granulocyte- bacterial clearance" and production of IgM and other macrophage colony-stimulating factor may ameliorate opsonin proteins.'^ the neutropenia in some cases.''^ Splenectomy is indi- cated only in patients with severe or recurrent neutro- penia or in tbose patients demonstrating recurrent and Hematologic Conditions resistant infections.-" Splenectomy results in increased Autoimmune Thrombocytopenia and Hemolytic Anemia granulocyte levels in 80 per cent of patients, with 55 per cent of patients experiencing no further infec- The pathogenesis of autoimmune thrombocytopenia tions.-' or idiopathic thrombocytopenic purpura (ITP) in- volves the formation of antibodies to several antigenic determinants, including glycoproteins llb/IIIa and hi/ Thrombocytopenic Purpura Ila.'"* The spleen is both a site of autoantibody pro- Thrombocytopenic purpura (TTP) presents with the duction and platelet destruction. Although ITP tends to pentad of fever, thrombocytopenia, hemolytic anemia, be a self-limiting disorder in the pediatric population, neurologic manifestations, and renal failure. TTP may No. 7 INDICATIONS