Pathology and causes
On physical examination of adults, the spleen should not be palpable. If it can be palpated, this indicates an increase of ≥1.5 times. The degree of enlargement of the spleen is determined by the distance from its defined edge to the left costal arch in centimeters.
Causes:
- infections – bacterial (tuberculosis, typhoid fever 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 lymphoma of the marginal zone, 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, obstruction of the portal (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’s disease, Niemann-Pick disease, mucopolysaccharidosis;
- other (rare) – cysts (congenital, post-traumatic, post-infarction, echinococcal), abscess, tumor metastases, benign and malignant tumors of the spleen, hemophagocytic lymphohistiocytosis.
An enlarged spleen can be the cause of hypersplenism, that is, sequestration and excessive destruction of blood cells (usually all, although it is limited to 1 or 2 cell lines) by splenic macrophages.
The signs of hypersplenism do not depend on the degree of enlargement of the spleen. If the increase is caused eg. amyloidosis or tumor metastasis, then hypersplenism is not observed (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 enlargement of the spleen and hypersplenism. Ultrasound and CT can assess the size of the spleen, the presence of focal changes, and additional spleens. Diagnostic tests depend on the suspected underlying disease. Note: If the distance from the defined edge of the spleen to the left costal arch is > 10 cm (usually the same as crossing the midline of the body), then the most common cause is a disease of the hematopoietic system.
Hypersplenism is confirmed by a complete blood count (cytopenia) and an aspiration biopsy of the bone marrow (enhanced hematopoiesis). The most reliable examination is scintigraphy using a radioactive isotope of technetium, which reveals an increased activity of splenic macrophages.