Pathology and causes
On physical examination in adults, the spleen should not be palpable. If palpable, this indicates a ≥1.5-fold magnification. The degree of enlargement of the spleen is determined by the distance from its defined border to the left costal arch in centimeters.
Causes:
- infections: bacterial (tuberculosis, typhoid and paratyphoid fever, brucellosis, infective endocarditis), viral (infectious mononucleosis, cytomegalovirus, viral hepatitis), protozoan (malaria, toxoplasmosis, leishmaniasis);
- myeloproliferative neoplasms: primary myelofibrosis, chronic myeloid leukemia;
- lymphoproliferative neoplasms: hairy cell leukemia, splenic marginal zone lymphoma, chronic lymphocytic leukemia;
- autoimmune and systemic diseases: rheumatoid arthritis, Felty's syndrome, systemic lupus erythematosus, drug reactions, sarcoidosis, primary and secondary amyloidosis;
- portal hypertension: liver cirrhosis, Budd-Chiari syndrome, portal obstruction (thrombosis, narrowing, congenital cavernosity, compression by lymph nodes and tumors) or splenic vein (thrombosis, narrowing, aneurysm or compression by pancreatic tumors or other neoplasms);
- hemolytic anemias: congenital and acquired (including autoimmune);
- acute leukemia (usually a slight increase);
- accumulation diseases: Gaucher disease, Niemann-Pick disease, mucopolysaccharidoses;
- other (rare): cysts (congenital, post-traumatic, post-infarct, echinococcal), abscesses, tumor metastases, benign and malignant tumors of the spleen, hemophagocytic lymphohistiocytosis.
An enlarged spleen may be the cause of hypersplenism, ie excessive sequestration and destruction of blood cells (usually all, but limited to 1-2 cell lines) by splenic macrophages.
Signs of hypersplenism do not depend on the degree of enlargement of the spleen. If the increase is due, eg. amyloidosis or tumor metastasis, then hypersplenism is not seen (there may be hyposplenism).
In the case of an enlarged spleen with lymphoproliferative neoplasms, the signs of hypersplenism, even with a large spleen, are not as pronounced as with portal hypertension or Gaucher disease.
Diagnostics
A negative palpation result does not exclude an enlarged spleen and hypersplenism. Ultrasonography and CT can assess the size of the spleen, the presence of focal changes, and additional spleens. Diagnostic tests depend on the suspicion of underlying disease. Note: If the distance from the defined border of the spleen to the left costal arch is >10 cm (usually the same as crossing the midline of the body), then disease of the hematopoietic system is the most common cause.
Hypersplenism is confirmed by a complete blood count (cytopenia) and bone marrow aspiration biopsy (increased hematopoiesis). The most reliable test is scintigraphy with a radioactive isotope of technetium, which reveals increased activity of splenic macrophages.