A Pyogenic Liver Abscess Masquerading as Advanced Hepatocellular Carcinoma: Diagnostic Pitfalls of LI-RADS 5 in a Non-Cirrhotic Patient and Vascular Complications of Percutaneous Drainage

Background: Liver abscesses represent uncommon yet potentially life-threatening infections of the hepatic parenchyma. Their imaging appearances can vary widely, and—in rare instances—may closely resemble hepatocellular carcinoma (HCC) on multimodality imaging. We report a case of pyogenic liver abscess initially misclassified as advanced HCC based on imaging characteristics meeting LI-RADS 5 criteria. Case Presentation: A 45-year-old male without known cirrhosis, viral hepatitis, or diabetes presented with right upper quadrant pain, abdominal rigidity, nausea, and vomiting. He denied alcohol use, recent dental procedures, and travel to endemic areas. Contrast-enhanced computed tomography and magnetic resonance imaging demonstrated multiple exophytic hepatic masses with arterial-phase hyperenhancement and venous/delayed washout, classified as LI-RADS 5 and initially interpreted as advanced HCC (BCLC stage C). Alpha-fetoprotein (AFP) was not elevated. Hepatitis B surface antigen and anti-HIV were non-reactive. Ultrasound-guided fine-needle aspiration biopsy yielded purulent material; histopathology confirmed chronic suppurative inflammation consistent with an abscess, with negative acid-fast bacilli staining. Cultures were sterile. The patient was treated with doripenem and metronidazole. A post-drainage complication of middle hepatic artery bleeding required urgent transcatheter embolization. The patient was subsequently discharged in stable condition. Discussion: This case illustrates a recognized but uncommon diagnostic pitfall: pyogenic liver abscesses fulfil imaging criteria for HCC. LI-RADS 5 classification carries an estimated false-positive rate of approximately 5%, and its application is technically restricted to patients with established HCC risk factors (e.g., cirrhosis, chronic hepatitis B). In non-cirrhotic patients presenting with fever, leukocytosis, and an atypical or rapidly enlarging hepatic mass, tissue confirmation is essential before committing to an oncological diagnosis. Conclusions: When a hepatic mass displays imaging features fulfilling LI-RADS 5 criteria in a non-cirrhotic patient with clinical signs of infection—including fever, leukocytosis, and elevated inflammatory markers—the possibility of a liver abscess must be actively excluded. Biopsy and percutaneous drainage are essential to avoid misdiagnosis and to enable timely, appropriate treatment.