The axial CTscans are from two different patients. The spleen in a, and overlaid in b is normal. The spleen in c and overlaid in d is enlarged. An extensive list for the differential diagnosis for splenomegaly exists and in large part the potential diagnosis is narrowed based on the background setting of the patient and associated clinical and imaging findings.

20712c01.8s  CTscan spleen normal enlarged splenomegaly

The spleen is situated in the left upper quadrant of the abdomen between the gastric fundus and the left hemidiaphragm. Its long axis lies in the plane of the 10th rib, where it rests on the left colic flexure.(1) The spleen normally lies deep to the left 9th, 10th, and 11th ribs and is vulnerable to injury if these ribs are fractured. The spleen’s ligamentous attachments to the stomach, diaphragm, and left kidney make it partially mobile so that it follows the diaphragm in its respiratory movements. Normally the spleen does not extend inferior to the left costal margin. The anterior tip of the spleen usually does not extend farther medially than the midclavicular line.(2)

The spleen has diaphragmatic and visceral surfaces, superior and inferior borders, and anterior and posterior extremities. The spleen lies in contact with the posterior wall of the stomach, and the tail of the pancreas ends at the splenic hilum.