Viral Hepatitis: The presentation of mildly hypoechoic liver parenchyma with a "starry sky" appearance, along with elevated liver enzymes and abdominal pain in a child, is highly suggestive of viral hepatitis. The "starry sky" appearance is characteristic of hepatitis due to the diffuse inflammation of the liver parenchyma.

Infectious Mononucleosis: Caused by Epstein-Barr virus (EBV), it can lead to hepatitis, which might present with similar ultrasound findings and elevated liver enzymes. Abdominal pain and systemic symptoms like fever and fatigue are common.
Autoimmune Hepatitis: Although less common in children, autoimmune hepatitis can present with elevated liver enzymes and abdominal pain. Ultrasound findings might be non-specific but could include a hypoechoic liver parenchyma.
Wilson's Disease: A genetic disorder leading to copper accumulation in the liver, which can cause liver dysfunction and might present with similar ultrasound findings, although typically with more significant liver enzyme elevations.

Malignancies (e.g., Hepatoblastoma): Although rare, pediatric liver malignancies can present with non-specific abdominal pain and elevated liver enzymes. The presence of subcentimetric nodes at the porta hepatis raises concern for potential metastatic disease.
Budd-Chiari Syndrome: A condition caused by hepatic vein thrombosis, which can lead to acute liver failure. It might present with abdominal pain, ascites, and liver dysfunction. Ultrasound findings can include hepatic vein thrombosis and liver parenchymal changes.
Vascular Malformations or Thrombosis: Conditions like portal vein thrombosis or hepatic artery thrombosis can cause liver dysfunction and might present with non-specific findings on ultrasound, including hypoechoic liver parenchyma.

Glycogen Storage Diseases: Certain types can lead to liver enlargement and elevated liver enzymes, but they typically present with more systemic symptoms and are diagnosed based on specific metabolic abnormalities.
Alpha-1 Antitrypsin Deficiency: A genetic disorder that can cause liver disease, presenting with elevated liver enzymes and potentially with liver ultrasound abnormalities, although it's less common in children without a family history.
Congenital Hepatic Fibrosis: A rare condition that can cause liver dysfunction and might present with ultrasound findings of liver parenchymal abnormalities, though it's typically associated with more significant clinical manifestations.