Traumatic rupture of a giant congenital splenic cyst presenting as peritonitis

Splenic cysts are uncommon, with large cysts and complications being rare. We describe a 6-year-old patient who initially presented 1 day after falling onto her abdomen at the playground with worsening abdominal pain and distention. An ultrasound of the abdomen demonstrated free abdominal fluid in all four quadrants. A subsequent contrast-enhanced computed tomography scan of the abdomen and pelvis was performed which showed a large splenic cyst with open communication to the peritoneal cavity. A congenital primary cyst was confirmed on pathology after partial splenectomy was performed. Although the majority of splenic cysts are asymptomatic, rupture can lead to acute peritoneal signs and mimic other significant causes of abdominal pain such as viscous injury or acute appendicitis.