Doughnut sign of hepatic alveolar echinococcosis on FDG PET/CT: Clinical case report

RATIONALE: A characteristic metabolic finding of hepatic alveolar echinococcosis (HAE) on positron emission tomography/computed tomography (PET/CT) correlates with morphologic features on CT and magnetic resonance imaging (MRI). PATIENT CONCERNS: A young man from an endemic area was admitted to our hospital due to right upper quadrant pain for 2 months. DIAGNOSIS: CT and MRI revealed a heterogeneous mass with calcification, consisting of central necrosis and peripheral solid inflammatory tissues. Accordingly, FDG PET/CT demonstrated a characteristic metabolic finding of doughnut sign. Combining the above characteristic imaging features with positive serologic findings, the patient was diagnosed as HAE. INTERVENTIONS: He then underwent extracorporeal hepatectomy and liver autotransplantation followed by medical treatment of benzimidazoles. OUTCOMES: He remained asymptomatic without evidence of recurrence at 2-year follow-up. LESSONS: The characteristic metabolic appearance of HAE on FDG PET/CT, correlated with its morphologic features of CT and MRI, may allow to make accurate diagnoses.