Hypersplenism is cytopenia caused by splenomegaly.
(See also Overview of the Spleen.)
Hypersplenism is a secondary process that can arise from splenomegaly of almost any cause (see Table: Common Causes of Splenomegaly). Splenomegaly increases the spleen’s mechanical filtering and destruction of RBCs and often of WBCs and platelets. Compensatory bone marrow hyperplasia occurs in those cell lines that are reduced in the circulation.
Hypersplenism is suspected in patients with splenomegaly and anemia or cytopenias. Evaluation is similar to that of splenomegaly.
Unless other mechanisms coexist to compound their severity, anemia and other cytopenias are modest and asymptomatic (eg, platelet counts, 50,000 to 100,000/μL; WBC counts, 2500 to 4000/μL with normal WBC differential count). RBC morphology is generally normal except for occasional spherocytosis. Reticulocytosis is usual.
Treatment is directed at the underlying disorder. However, if hypersplenism is the only serious manifestation of the disorder (eg, Gaucher disease), splenic ablation by splenectomy or radiation therapy may be indicated. The indications for splenectomy or radiation therapy in hypersplenism are detailed below (see Table: Indications for Splenectomy or Radiation Therapy in Hypersplenism).
Because the intact spleen protects against serious infections with encapsulated bacteria, splenectomy should be avoided whenever possible, and patients undergoing splenectomy require vaccinationagainst infections caused by Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae.
After splenectomy, patients are particularly susceptible to severe sepsis with encapsulated microorganisms and are often given daily prophylactic antibiotics such as penicillin or erythromycin. Patients who develop fever should receive empiric antibiotics.