Abstract
A 69-year-old man with dementia presented to our hospital with fever and left back pain. He was diagnosed with acute pyelonephritis based on microscopy and CT findings indicating bacteriuria and elevated fat density around the right kidney, respectively. Three days post admission, the diagnosis of a urinary tract infection was queried and the patient was re-examined. Marked tenderness was observed in the left buttock; contrast CT scan was subsequently performed and a left piriformis abscess was diagnosed. This diagnostic delay occurred due to a communication error-the referral letter to the radiologist stated 'fever and back pain'-and the physician's hyposkillia; hence, differential diagnoses were not considered. Physicians can reduce the frequency of related errors by conducting proper physical examinations and not relying on imaging findings alone. Furthermore, to ensure accurate diagnoses, the comments to the radiologist should be clear and detailed when requesting diagnostic imaging.