A 72-years-old woman of polyarteritis nodosa had fever, running nose, and nasal obstruction for 3 days. In emergency room, rapid influenza diagnostic test in nasopharyngeal swab was positive for influenza B on October 31, 2015. Chest X-ray (CXR) showed slight infiltration on bilateral lungs. A white blood cell count was 16,100/μL and an elevated C-Reactive Protein (CRP) level was 238.0 mg/L. Initial renal function was normal. Other data of laboratory testing were tabulated in Table 1.