CHAPTER 18 Splenectomy
INDICATIONS FOR SPLENECTOMY
I. Platelet-Associated: ITP is the most common indication for elective splenectomy. ITP is caused by circulating autoantibodies that bind to platelet membrane antigens and facilitate phagocytosis in the spleen and elsewhere.
A. Patients with ITP commonly present with a history of bruising, epistaxis, and gingival bleeding. Life-threatening complications, such as gastrointestinal or intracranial hemorrhage, are much less common. Women are affected more often than are men; however, in children, ITP affects both sexes equally. ITP in children is typically characterized by a more rapid onset and a more severe course than in adults. Spontaneous remission occurs in approximately 80% of affected children, and splenectomy should be reserved for cases of severe refractory ITP lasting longer than 1 year in this patient population.
B. Therapy for ITP is aimed at achieving sustained remission. In patients with asymptomatic disease, treatment is indicated for platelet counts between 20,000/mm3 and 30,000/mm3 or for platelet counts less than 50,000/mm3 with additional risk factors for bleeding, such as hypertension and peptic ulcer disease. Initial treatment consists of glucocorticoids. In patients with platelet counts less than 20,000/mm3 or with life-threatening bleeding, hospitalization is indicated. IVIG plays an important role in the management of acute bleeding as well as in the surgical preparation of patients with platelet counts of less than 20,000/mm3. Splenectomy is indicated in patients with thrombocytopenia refractory to steroids and IVIG, steroid-associated side effects, or recurrent thrombocytopenia after steroid treatment.
II. Erythrocyte-Associated
A. Hereditary spherocytosis (HS): HS is an autosomal dominant hemolytic anemia caused by a deficiency of spectrin, a protein that gives red blood cells their shape, strength, and flexibility. Erythrocytes that are deficient in spectrin lose surface area and deformability and have a characteristic spherical shape. Spherocytes are sequestered in the microcirculation of the spleen and destroyed. Patients with HS most commonly present with anemia, jaundice, and splenomegaly. Splenectomy significantly improves the anemia by eliminating the predominant site of red cell destruction. Splenectomy should be delayed until after 4 years of age to preserve immunologic function and reduce the risk of overwhelming postsplenectomy infection (see Complications). Given the high incidence of bilirubin gallstones in patients with this disorder, an abdominal ultrasound should be performed before splenectomy. If cholelithiasis is present, cholecystectomy should be performed at the time of splenectomy.
B. Hemoglobinopathies: Inherited disorders of hemoglobin synthesis, such as sickle cell disease and the thalassemias, are associated with increased erythrocyte destruction and anemia.
1. Sickle cell disease results from a genetic mutation in the beta globin chain that causes an abnormal hemoglobin tetramer (hemoglobin S). Deoxygenated hemoglobin S polymerizes within erythrocytes, leading to the characteristic sickle shape. These red blood cells can occlude capillaries and lead to microinfarction within various organ systems. Repeated vaso-occlusive insults cause the spleen to infarct and atrophy. Splenic sequestration crisis is characterized by a marked decrease in the hemoglobin concentration, hypovolemia, and splenomegaly. Patients may experience severe pain and require multiple blood transfusions. Splenectomy is indicated after a first episode of acute splenic sequestration and in patients with hypersplenism.
2. The thalassemias are a group of disorders resulting from abnormal synthesis of one of the hemoglobin chains. Patients with these disorders present with varying degrees of anemia and splenomegaly. Transfusions and iron chelation are the hallmarks of long-term treatment. Splenectomy is indicated in patients with increasing transfusion requirements and symptomatic splenomegaly.
C. Autoimmune hemolytic anemia (AIHA): AIHA is a term that describes a group of disorders characterized by the presence of autoantibodies that bind to the surface of erythrocytes and lead to hemolysis.
1. In warm-antibody AIHA, so named because the predominant IgG antibodies preferentially bind at 37°C, tissue macrophages within the spleen recognize antibody-bound erythrocytes and remove them from the circulation. Initial treatment consists of steroid therapy or other immunosuppressive agents. Splenectomy eliminates the major site of hemolysis and should be performed in patients in whom medical therapy is unsuccessful and in those who cannot receive corticosteroids.
III. Leukocyte-Associated
A. Hodgkin’s lymphoma: Hodgkin’s lymphoma is a malignancy that predominantly affects young adults. Historically, the staging of Hodgkin’s lymphoma required laparotomy and splenectomy. Improvements in computed tomography (CT) scanning and other imaging modalities have made surgical staging far less important in directing treatment. Splenectomy is indicated for symptomatic splenomegaly.
B. Non-Hodgkin’s lymphoma (NHL): NHL constitutes a diverse group of primary malignancies of the lymphoreticular tissue. Splenectomy is indicated in patients with hypersplenism resulting in anemia, thrombocytopenia, neutropenia, or symptomatic splenomegaly. NHL limited to the spleen is an additional indication for splenectomy.
C. Hairy cell leukemia (HCL): HCL is characterized by splenomegaly, pancytopenia, and evidence of cell membrane projections on microscopy. Purine analogues constitute first-line treatment. Splenectomy is reserved for patients with disease refractory to medical therapy and those with symptomatic splenomegaly.
D. Chronic lymphocytic leukemia: Chronic lymphocytic leukemia is a lymphoproliferative disorder characterized by the accumulation of functionally incompetent lymphocytes of monoclonal origin. Splenectomy is indicated for symptomatic splenomegaly and for hypersplenism.
E. Chronic myelogenous leukemia (CML): CML is a myeloproliferative disorder characterized by clonal proliferation of myeloid cells at all stages of maturation. A chromosomal translocation between chromosomes 9 and 22 (Philadelphia chromosome), which leads to the elaboration of a novel fusion protein (Bcr-Abl), is critical to the pathogenesis of this disease. Treatment of CML includes tyrosine kinase inhibitors and hematopoietic stem cell transplantation. Splenectomy may be performed for symptomatic splenomegaly or hypersplenism.
IV. Nonhematologic Abnormalities of the Spleen
A. Tumors: Primary nonlymphoid tumors of the spleen are uncommon. Hemangiomas are the most common benign primary tumor of the spleen and are sometimes associated with splenic rupture and thrombocytopenia when large. Splenectomy is indicated for symptomatic lesions. Splenic hamartomas and lymphangiomas are benign tumors and are rarely associated with symptoms. Splenectomy is sometimes performed for diagnostic purposes. Angiosarcomas are highly aggressive tumors with a poor prognosis. Patients may present with splenomegaly, hemolytic anemia, or spontaneous splenic rupture. Splenectomy is indicated, but is most often palliative. Metastases to the spleen are uncommon and are usually indicative of disseminated disease. Splenectomy may be appropriate if the spleen is the site of an isolated metastasis.
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