The spleen normally lies in the left upper quadrant, related to the superolateral aspect of the left kidney. The main supporting structures include the lienogastric ligament (connects the greater curvature of the stomach to the ventral aspect of the spleen), the lienorenal ligament (invests the splenic vessels), and the phrenicocolic ligament (forms a sling in which the lower pole of the spleen rests). The etiology of ectopic or wandering spleen is probably twofold: congenital abnormal development in the fetal dorsal mesogastrium; and acquired factors, including a ligamentous laxity due to hormonal stimulation during pregnancy or an enlarged spleen stretching the ligaments. The female-to-male incidence is 20 to 1, most often during childbearing years. The main significance of ectopic spleen is its predisposition for torsion, which may have a mortality of 50%. The films included demonstrate some of the classic plain film, ultrasound, and nuclear medicine findings.

Splenic cysts may be true or false cysts. The true cysts include those lined by a secreting membrane, and parasitic cysts. The false cysts include those resulting from hemorrhage or inflammation, and those due to liquefaction of areas of infarction. Ultrasound is the simplest way to demonstrate the organ of origin of a splenic cyst. Other focal splenic defects include abscess, hematoma, infarct, lymphoma, metastasis, and vascular tumor.