Splenomegaly

From Medical-Wiki

Splenomegaly is the enlargement of the spleen. The spleen is an organ with multiple functions. It plays a significant role in immunosurveillance and hematopoiesis. Overall, the four most important functions of the spleen are clearance of microorganisms and particulate antigens from the blood stream; synthesis of immunoglobulin G (IgG), properdin (ie, an essential component of the alternate pathway of complement activation), and tuftsin; removal of abnormal red blood cells (RBCs); and embryonic hematopoiesis in certain diseases.

Etiology

When considering the causes of splenomegaly, there are 6 basic etiologies:

• These are immune response work hypertrophy such as in subacute bacterial endocarditis or infectious mononucleosis
• RBC destruction work hypertrophy such as in hereditary spherocytosis or thalassemia major
• congestive such as in splenic vein thrombosis or portal hypertension
• myeloproliferative such as in chronic myeloid metaplasia
• infiltrative such as in sarcoidosis and some neoplasms
• neoplastic such as in chronic lymphocytic leukemia and the lymphomas.

Miscellaneous causes of splenomegaly include trauma, cysts, hemangiomas, metastasis, giant abscess, and certain drugs (eg, RhoGAM). [1]

Differential diagnosis

When considering causes of splenomegaly, they may be broken down into classes:

• Congestive causes include hepatic cirrhosis, portal hypertension, congestive heart failure, portal vein thrombosis, and splenic vein thrombosis.
• Neoplastic causes include lymphomas, e.g. Hodgkin’s disease, lymphocytic leukemias, myeloproliferative disorders e.g. polycythemia vera, myelofibrosis with myeloid metaplasia and chronic granulocytic Leukæmia, and chronic granulocytic leukæmia.
• Infectious causes include infectious mononucleosis, infective endocarditis, systemic cytomegalovirus infection, malaria, toxoplasmosis, infectious hepatitis, miliary tuberculosis, brucellosis, psittacosis, and syphilis.
• Inflammatory causes include sarcoidosis and amyloidosis.
• Connective tissue disorders that may cause splenomegaly include Systemic lupus erythematous, Rheumatoid arthritis.
• Hemaglobin disorders include . thalassæmias, certain sickle cell disorders, congenital Heinz body haemolytic anæmia), erythrocyte shape abnormality anæmias (e.g. hereditary spherocytosis/elliptocytosis), erythrocyte enzymopathies e.g. pyruvate kinase deficiency).
• Storage diseases that are causes include diseases both lipoid (e.g. Gaucher’s disease, Hand-Schüller-Christian disease and Niemann-Pick disease) and non-lipoid (e.g. Letterer-Siwe disease. [2] [3]