Mycotic aneurysm of the thoracic aorta presenting as pneumonia

Mycotic aneurysms of the thoracic aorta rarely occur in children. We report an unusual case of a mycotic aneurysm of the descending aorta in a 4-year-old boy presenting with respiratory tract infection, which was rapidly complicated by atelectasis of the left lung. The patient's mycotic aortic aneurysm was diagnosed by contrast-enhanced spiral CT, whereas conventional chest radiographs did not detect its presence. An unsuspected mild aortic coarctation was also diagnosed at the time of admission. This case demonstrates that an aortic aneurysm may clinically and radioiogically manifest itself with respiratory tract infection and atelectasis and that contrast-enhanced spiral CT is a fast and powerful tool for establishing the diagnosis.