A 70-year-old woman presented to the emergency department with a 3-week history of prolonged fever, asthenia and anorexia, denying other symptoms. Physical examination was unremarkable and the patient admitted for further investigation. Initial laboratory testing showed leucocytosis, elevated C-reactive protein and cholestasis, without hyperbilirubinemia or cytolysis. Abdominal ultrasonography found no abnormalities. Viral serologies, autoimmune tests and blood cultures were collected for further investigation of causes of prolonged fever with hepatic involvement. After two days, Citrobacter koseri was isolated in blood cultures and intravenous (IV) piperacillin-tazobactam initiated. Computed tomography (CT) scan of the abdomen showed a left lobe hepatic abscess with gas and a linear hyperdense image, possibly a foreign body, piercing through the gastric antrum into the abscess. Surgical exploration was done for source control. The abscess was drained and the foreign body, a 3.5 cm long fishbone, was removed. The patient's condition rapidly improved. Gastrointestinal perforation due to the ingestion of sharp and elongated foreign bodies usually occur in ileal loops, where the intestinal wall is thinner, causing extravasation of fluids and air into the peritoneum and typically presents with an acute abdomen. The uncommon location of perforation masked these symptoms leading to the unusual presentation with prolonged fever.