A spleen was an organ that several organisms possessed, including Humans and dianogas.
Spleens could rupture or suffer from spleen-rot. Dianogan tea was made from the spleens of dianogas.
During the Yuuzhan Vong War, the Jedi Anakin Solo was critically injured when his spleen was ruptured. The internal bleeding caused by the organ's perforation led to his death.