Surgical Debulking for Refractory Hyperammonemic Encephalopathy in Fibrolamellar Hepatocellular Carcinoma.

A 26-year-old male with a two-year history of FLC developed progressive somnolence and disorientation. Treatment history for FLC had included cytotoxic chemotherapy, lenvatinib, and immunotherapy. A CT scan confirmed extensive stage FLC with numerous liver, lung, and pelvic metastasis. Laboratory results showed bilirubin 0.3 mg/dL, creatinine 0.4 mg/dl, leukocytes of 9.5x10 /L, hemoglobin 11.2 g/dL, platelets 369x10 /L, and ammonia 247 µmol/L (reference range: 0-32 µmol/L). Plasma amino acid analysis revealed relatively low citrulline (14 µmol/L), arginine (32 µmol/L), and ornithine (35 µmol/L). Urinary orotic acid excretion was markedly elevated at 149 mmol/mol creat (reference range: 0.68-3.52 mmol/mol creat).