- Gastrointestinal (duplication, mesenteric cyst) – accounts for ~ 15% of abdominal masses in neonates
- Gynecologic (ovarian cyst, ovarian teratoma) – accounts for ~ 15% of abdominal masses in neonates
- Hepatobiliary (choledochal cyst, hepatic hemangioma, mesenchymal hamartoma) – accounts for ~ 5% of abdominal masses in neonates
- Retroperitoneal (adrenal hemorrhage, neuroblastoma) – accounts for ~ 10% of abdominal masses in neonates
Approach to differential diagnosis of non-renal causes of abdominal masses in neonates which accounts for ~ 50% of abdominal masses in neonates:
- Adrenal masses (adrenal hemorrhage and neuroblastoma) – negative laboratory studies and serial ultrasound exams with decreasing mass size are the key to diagnosing adrenal hemorrhage and differentiating it from neuroblastoma
- Cystic mass with echogenic rim sign on US is a gastrointestinal duplication
- Simple cystic mass can be identified as ovarian in origin if other ovarian follicles are associated with it, otherwise ovarian cyst and mesenteric cyst can be indistinguishable
- Liver cystic masses can be distinguished as to whether they communicate with the biliary tree (choledochal cyst) or not (mesenchymal hamartoma)
Pediatric Imaging 