Definition

A palpable spleen is the major physical sign produced by diseases affecting the spleen and suggests enlargement of the organ. The normal spleen is said to weigh less than 250 g, decreases in size with age, normally lies entirely within the rib cage, has a maximum cephalocaudal diameter of 13 cm by ultrasonography or maximum length of 12 cm or width of 7 cm by radionuclide scan, and is usually not palpable.

Incidence and prevalence

A palpable spleen was found in 3% of 2200 asymptomatic male freshman college students. Follow-up at 3 years revealed that 30% of those students still had a palpable spleen without any increase in disease prevalence. Ten-year follow-up found no evidence for lymphoid malignancies. Furthermore, in some tropical countries (e.g., New Guinea), the incidence of splenomegaly may reach 60%. Thus, the presence of a palpable spleen does not always equate with the presence of disease.

Pathophysiology

Hyperplasia or hypertrophy is related to a particular splenic function such as reticuloendothelial hyperplasia (work hypertrophy) in diseases such as hereditary spherocytosis or thalassemia syndromes that require removal of large numbers of defective red blood cells and to immune hyperplasia in response to systemic infection (infectious mononucleosis, subacute bacterial endocarditis) or to immunologic diseases (immune thrombocytopenia, systemic lupus erythematosus, Felty’s syndrome). Passive congestion results from decreased blood flow from the spleen in conditions that produce portal hypertension (cirrhosis, Budd-Chiari syndrome, congestive heart failure). Infiltrative diseases of the spleen include lymphomas, metastatic cancer, amyloidosis, Gaucher’s disease, and myeloproliferative disorders with extramedullary hematopoiesis.

The differential diagnostic possibilities are fewer when the spleen is “massively enlarged,” that is, it is palpable more than 8 cm below the left costal margin or its drained weight is 1000 g or more. Most such patients have non-Hodgkin’s lymphoma, chronic lymphocytic leukemia, hairy cell leukemia, chronic myelogenous leukemia, myelofibrosis with myeloid metaplasia, or polycythemia vera.