An adolescent girl presented to her pediatrician reporting abdominal distention. She first became aware of her increased abdominal girth when friends at school asked whether she was pregnant. She had noticed her clothing becoming tighter over recent weeks. She had not experienced abdominal pain or other symptoms, and there was no history of trauma. Physical examination revealed a firm, distended abdomen without bowel sounds. Pregnancy test results were negative. Results of laboratory studies, including a complete blood cell count, basic metabolic panel, and liver function tests, were within normal limits. An abdominal radiograph showed a paucity of bowel gas markings (Figure 1A). A subsequent computed tomographic scan of the abdomen and pelvis revealed a 30-cm retroperitoneal cystic structure causing significant mass effect on the abdominal viscera, displacing the right kidney superiorly under the liver causing moderate hydronephrosis (Figure 1B).
Bruns NE, Falk GA, Stallion A. Massive Retroperitoneal Cystic Mass in an Adolescent. JAMA Pediatr. 2015;169(6):601-602. doi:10.1001/jamapediatrics.2015.0424