Splenomegaly refers to enlargement of the spleen. The upper limit of normal adult splenic length is traditionally cited at 12 cm, but lengths upwards of 14 cm can be seen in normal, taller males .
Massive splenomegaly is variably defined, including when the spleen is 5 standard deviations above the mean normal volume (about 943 cm) , heavier than 1000 g or 1500 g ,longer than 18 cm , or extending into the pelvis or across midline .
The causes of splenomegaly are protean, and can be thought of under a number of headings :
- hematological disease
- storage diseases/metabolic/infiltrative disorders
- neoplastic (non-hematologic)
- connective tissue disorders
- neoplastic/proliferative/redistribution of hematopoiesis
- myeloproliferative neoplasms*
- acute leukemia*
- lymphoma / chronic lymphoid neoplasms*
- extramedullary hematopoiesis
- idiopathic hypereosinophilic syndrome
- cirrhosis: portal hypertension (common)
- congestive splenomegaly (Banti syndrome)
- splenic vein obstruction
- portal vein obstruction
- right heart failure
- cystic fibrosis
- parasitic disease
Storage diseases/metabolic/infiltrative disorders
- Gaucher disease*
- glycogen storage disease
- Niemann-Pick disease
Connective tissue disorders
- rheumatoid arthritis
- systemic lupus erythematosus (SLE)
* may cause massive splenomegaly
The shape and orientation of a spleen make accurate linear measurement difficult.
On CT, a splenic width measurement (largest anterior-posterior measurement on axial images) of greater than 10.5 cm is the most accurate single measurement for mild to moderate splenomegaly in patients with cirrhosis; while a craniocaudal measurement of greater than 14.6 cm is the most accurate single measurement for massive splenomegaly .
On sonographic assessment, a length of 12 cm is generally considered the upper limit of normal.