An unusual cause of abdominal pain

A 69 year old woman presented with a three month history of pain in her right iliac fossa and 13 kg of weight loss, with no other symptoms. She was a heavy smoker, with a previous medical history of spinal osteoarthritis, varicose vein surgery, and pyelonephritis. She had no noteworthy family history. On examination the patient was apyrexial and in obvious discomfort. She was normocardic, with a blood pressure of 175/104 mm Hg, and she had a palpable pulsatile expansile epigastric mass. Blood investigations were entirely normal other than a raised C reactive protein at 138 mg/l. A computed tomography scan was taken (fig 1).