Snapshot A 50-year-old man presents to the emergency department with perforated diverticulitis. He undergoes an emergency laparatomy and left-sided hemicolectomy. He is started on intravenous fluids and broad spectrum antibiotics via a central line. His sepsis resolves, but he continues to have ileus and is started on total parenteral nutrition. By the tenth post-operative day, his temperature is 100.8°F (38.2°C). His leukocyte count is 10,900/mm3. There is no foci of infection on physical exam. Urinalysis, complete metabolic panel, and liver function tests are within normal limits. Blood and urine cultures are negative. Chest radiograph, CT scan of abdomen, and CT scan of pelvis are unremarkable. The central line was replaced, but the patient still has fever and leukocytosis. Differential and Evaluation Infectious (infection and cancer account for > 60%) TB endocarditis Cancer leukemias lymphomas Autoimmune (15%) Still's disease SLE temporal arteritis PAN Miscellaneous Whipple's disease recurrent pulmonary emboli alcoholic hepatitis Undiagnosed (10-15%) Treatment Severely ill patients can be started on broad spectrum antibiotics discontinue if the patient does not respond