DDX of abdominal mass in neonate – non-renal causes

Approach to DDX 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 key to differentiating
  • 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)