What does having an enlarged spleen mean?

An enlarged spleen is, obviously, when the spleen is larger than it is supposed to be. There are many causes of an enlarged spleen. Here is a list, courtesy of merckmanuals.com:

Infections - Brucellosis Hepatitis Infectious mononucleosis Kala-azar Malaria Psittacosis Subacute bacterial endocarditis Syphilis Tuberculosis Anemias - Hereditary elliptocytosis Hereditary spherocytosis Sickle cell disease (mainly in children) Thalassemia Blood cancers and myeloproliferative disorders - Hodgkin lymphoma and other lymphomas Leukemia Polycythemia vera Myelofibrosis Storage diseases - Gaucher’s disease Hand-Schüller-Christian disease Letterer-Siwe disease Niemann-Pick disease Wolman’s disease Other causes - Amyloidosis Blood clot in a vein from the spleen or to the liver Cirrhosis Cysts in the spleen External pressure on veins from the spleen or to the liver Felty’s syndrome Sarcoidosis Systemic lupus erythematosus (lupus)