Splenic cysts are relatively uncommon, and are usually asymptomatic. They are benign, typically treated conservatively and followed up with ultrasound examination, with few reported complications. We report a case of a simple splenic cyst that was followed up on imaging over a seven-year period. During that time, the cyst gradually enlarged from 5 cm to 12 cm in diameter, however the patient remained asymptomatic. After seven years, the patient was admitted with abdominal pain and a pelvic mass. The spleen was located within the pelvis, which was felt to be due to the weight of the cyst which caused the spleen to migrate out of its normal position. This case illustrates an extremely unusual complication, and suggests that while most splenic cysts may be managed conservatively, enlarging cysts may be prone to gravitational effects and prophylactic treatment should be considered.