Fever of Unknown Origin: A Case Report of Hepatic Phlegmon in an Immunocompetent Patient.

Methicillin-resistant Staphylococcus aureus (MRSA) hepatic phlegmon is a rare cause of fever of unknown origin (FUO) in an immunocompetent patient from a high-income country (HIC). MRSA hepatic phlegmon is typically linked to protein malnutrition and chronic gastrointestinal infections in low- to middle-income countries while immunodeficiencies such as chronic granulomatous disease (CGD) are a more common cause in a HIC. Clinical manifestations of hepatic phlegmon can be vague and nonspecific making a complete FUO workup critical during evaluation. We report a case of MRSA hepatic phlegmon in an immunocompetent patient with a nonspecific history and physical exam findings. A 14-year-old male presented with an 11-day history of fever with mild bilateral upper quadrant abdominal pain. The patient also has mild upper quadrant pain with palpation. The patient was diagnosed with a hepatic phlegmon on abdominal ultrasound and computed tomography (CT) of the abdomen. He was started on antibiotics and Interventional Radiology placed drains into the phlegmon and performed vancomycin drain washes. Inflammatory markers were initially elevated and trended down with interventions. The patient did well with treatment and was back to baseline during outpatient follow-up with the Infectious Disease team. This case illustrates the importance of a complete workup in patients with FUO.