Aortitis causing rapid growth of a mycotic aortic aneurysm

Mycotic infrarenal aortic aneurysms are rare and often masquerade as other abdominal pathology. We present a case where serial imaging made the diagnosis and provided an insight into the pathophysiology of mycotic aneurysm. A 71-year-old man presents with abdominal pain, rigours and dysuria. Computed tomography reveals an irregular, thickened ectatic abdominal aorta, but cholescintigraphy suggests acalculous cholecystitis. Deterioration prompts repeat radiographical assessment, which demonstrates an increase in the size of the aorta over 10 days. The patient was treated emergently with an open aortic ligation, debridement and extra-anatomical bypass. Infections account for up to 2% of abdominal aortic aneurysms. The rate of growth of mycotic aneurysms is sparsely discussed in the literature and to our knowledge, there are no reports with serial single-modality imaging. The most significant finding was rapid expansion in aneurysm size. While mycotic aneurysm requires urgent treatment, diagnosis can be delayed and difficult.