Splenomegaly

Last updated: July 12, 2021

Summary

Splenomegaly is enlargement of the spleen. The etiology is diverse and may result from increased splenic activity, decreased venous drainage, or infiltration of the spleen. Symptoms are seldom caused by the size of the spleen directly, but rather due to its hematologic effects on the different cell lines, which manifest as anemia, leucopenia, thrombocytopenia, or as a combination of these (i.e., pancytopenia). Diagnosis can be made by palpation of the spleen in the left upper quadrant, especially on deep inspiration. Imaging studies such as sonography and CT help detect subclinical splenomegaly. Refractory symptoms may necessitate a splenectomy. Vaccination against encapsulated pathogens is essential to reduce the incidence of overwhelming post-splenectomy infection (OPSI).

Pathophysiology of splenomegaly

Pathophysiology

Overview of causes of splenomegaly ^[1]
Cause	Pathophysiology	Associated diseases
Increased splenic activity	Increased degradation of defective or structurally abnormal blood cells (work hypertrophy)	Hemolytic anemias (e.g., spherocytosis, thalassemia, early sickle cell disease) Polycythemia vera
	Increased immune response	Viral infections (e.g., CMV, EBV, viral hepatitis) Bacterial infections (e.g., leptospirosis, brucellosis, tuberculosis) Mycotic infections (e.g., histoplasmosis) Parasitic infections (e.g., malaria, trypanosomiasis, leishmaniasis)
	Defective immune response	Vasculitis Connective tissue disease Rheumatoid arthritis SLE Sarcoidosis ITP
	Compensatory extramedullary hematopoiesis within the spleen due to conditions involving bone marrow deficiency	Myelofibrosis Bone marrow involvement Hodgkin lymphoma, NHL Leukemias Toxicity/radiation
Decreased venous drainage	Portal hypertension	Liver cirrhosis Obstruction of portal, hepatic or splenic vein Schistosomiasis
Splenic infiltration	Suppression of splenic tissue	Hodgkin lymphoma, NHL Leukemia (e.g., hairy cell leukemia, CML) Metastatic tumors: melanoma Benign tumors (e.g., hamartomas) Metabolic diseases Gaucher disease Niemann-Pick Amyloidosis Hurler syndrome and other mucopolysaccharidoses

Splenomegaly Abdomen of a patient with malaria Splenic rupture due to splenomegaly Examination of the Spleen - Clinical Examination

Massive splenomegaly

Definition: spleen is palpable more than 8 cm below costal arch, > 20 cm in diameter, and/or weight > 1000 g ^[1]
Associated with ^[1]
- CML and CLL
- Myelofibrosis
- Polycythemia vera
- Rare: hairy cell leukemia, Hodgkin lymphoma and non-Hodgkin lymphoma

Myeloproliferative disorders are commonly accompanied by splenomegaly.
Massive splenomegaly

Hypersplenism

Definition: an overactive spleen
Causes: see “Increased splenic activity” in the table above
Pathomechanism: overactive spleen → cells are removed from the blood faster than normal → ↓ of a single or combination of cell lines, including possible cytopenia (pancytopenia, leukopenia, anemia, and thrombocytopenia) → reactive bone marrow hyperplasia (unless defective bone marrow is the cause of splenomegaly)
Clinical features
- Enlarged spleen
- Low levels of one or more types of blood cells
  - Anemia: pallor, fatigue, signs of hemolysis
  - Thrombocytopenia: ↑ risk of bleeding
  - Leukopenia: ↑ risk of infection
  - Pancytopenia
Treatment
- Treatment of underlying disease
- Splenectomy in case of symptomatic cytopenia
  - After splenectomy there is an increased risk of infection by encapsulated pathogens, possibly leading to overwhelming post-splenectomy infection (OPSI) → prevention with vaccinations against pneumococci, meningococci, and Haemophilus influenzae type B
  - Although not an encapsulated organism, a yearly influenza vaccine is also recommended

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