A 91-year-old woman with a past medical history of hypertension and hyperlipidemia was referred by her family physician to our Emergency Department (ED) for suspected appendicitis. She complained of 1 week history of right iliac fossa pain, subjective fever, and anorexia. The pain was colicky, with no radiation, and was associated with some urinary frequency. She had been healthy prior to this episode. At triage, she had a pulse rate of 88 beats/min, blood pressure of 98/56, and a temperature of 35.9°C. Examination of the abdomen revealed right iliac fossa tenderness together with guarding and rebound tenderness extending to the right flank and back. There were no external signs of a cutaneous infection such as warmth, erythema, crepitus, or open wounds. Initial blood investigations revealed a raised white count of 25 × 10 9 /L (normal range, 4-10 × 10 9 cells/L) with neutrophilia, and a C-reactive protein level of 277 mg/L (0.2-9.1 mg/L). Her lactate was elevated at 4.4 mg/dL. Microscopic urinalysis was unremarkable and an erect chest radiograph showed no free air. A computed tomography (CT) scan of her abdomen and pelvis was ordered and revealed a large multi-loculated right iliopsoas abscess, measuring 7.0 cm by 22.0 cm by 12.5 cm, spreading in the retroperitoneal space from the