This is enlargement of the spleen,and is usually secondary to other conditions,eg.infections,circulatory disorder,blood diseases,malignant neoplasms.
INFECTIONS.
The spleen may be infected by blood-borne microbes or by local spread of infections. The red pulp becomes congested with blood and there is an accumulation of phagocytes and plasma cells.
Chronic infections. Some chronic non-phogenic infections cause splenomegaly,but this is usually less severe than in the case of acute infections. The most commonly occurring primary infections include:
- Tuberculosis.
- Typhoid fever.
- Malaria.
- Brucellosis.
- Infectious mononucleosis.
CIRCULATORY DISORDER.
Splenomegaly due to congestion of blood occurs when the flow of blood through the liver is impeded by,eg,fibrosis in liver cirrhosis,or portal venous congestion in right-sided heart failure.
BLOOD DISEASE.
Splenomegaly may be caused by blood disorders. The spleen enlarged to deal with the extre workload associated with removing damaged,worn out and abnormal blood cells in,eg,haemolytic and macrocytic anaemia,polycythemia and chronic myeloid leukemia.
Splenomegaly may itself cause blood disorders. When the speen is enlarged for any reason,especially on portal hypertension,excessive and premature haemolysis of red cells or phagocytosis of normal white cells and platelets leads to marked anaemia,leukopenia and thrombocytopenia.
TUMOURS.
Benign and primary malignant tumours of the spleen are rare but blood-spread tumour fragments from elsewhere in the body may cause metastases. Splenomegaly caused by infiltration of malignant cell is characterised of some conditions,especially chronic leukaemia.
