S3111 An Unusual Case of Acute Liver Failure Secondary to Autoimmune Hepatitis (AIH) From Drug-Induced Liver Injury (DILI)

Abstract

Introduction: A broad differential diagnosis and detailed workup is necessary in the evaluation of acute liver failure, as the below case demonstrates. Case Description/Methods: A 68-year-old Caucasian man presented to the ED complaining of chronic right lower quadrant pain, worsening over the last few weeks. He reported taking up to 20 tablets of naproxen a day. Review of systems was positive for diffuse pruritis of recent onset. Past medical history consisted of COPD, inguinal hernia status post mesh repair, knee osteoarthritis and a cholecystectomy. He endorsed daily tobacco use and minimal alcohol intake. Medications consisted of Albuterol inhaler and Naproxen. He had been diagnosed with a urinary tract infection one month prior that was treated with a ten-day course of Cephalexin. Exam was notable for diffuse excoriation and right upper/lower quadrant tenderness. Initial labs demonstrated creatinine 0.87, AST 2635, and ALT 887, with the remainder of his comprehensive metabolic panel being normal. Contrasted CT scan of the abdomen and pelvis revealed no abnormalities. A right upper quadrant ultrasound was notable for left sided intrahepatic biliary dilatation. Over the next day, his mentation worsened, with repeat labs notable for bicarbonate 13, creatinine 3.08, AST 12050, ALT 3950, total bilirubin 2.4 with direct bilirubin 1.5, INR 3.11 and ammonia 164. A broad infectious workup was unremarkable including negative viral hepatitis serologies. Smooth muscle antibody was weakly positive at a low titer of 1:20. Anti-nuclear and anti-mitochondrial antibodies were negative. Serum IgG level was normal. Endoscopic retrograde cholangiopancreatography revealed a severe left intrahepatic biliary stricture with resulting stent placement into the left hepatic duct. Bile duct brushing was negative for atypical cells. Liver biopsy demonstrated centrilobular necrosis and parenchymal collapse with focal bridging necrosis and mixed inflammatory infiltrate. A diagnosis of AIH secondary to DILI leading to acute liver failure was made, with either Naproxen or Cephalexin being the inciting drugs. Discussion: He was started on a prednisone taper and showed improvements in mental status and kidney and liver function on lab-work prior to discharge. Labs obtained on clinic follow-up one month after discharge revealed complete resolution of his kidney and liver injury. This case illustrates a rare clinical entity as neither Naproxen nor Cephalexin are classically associated with causing AIH or acute liver failure.