Mycotic thoracic aortic arch aneurysm from haematogenous spread of Clostridium septicum due to metastatic colorectal cancer: a survival guide

We report the case of a 78-year-old female who was found to have a mycotic thoracic aortic arch aneurysm caused by Clostridium septicum. Subsequent investigations demonstrated adenocarcinoma of the caecum with two liver metastases. The patient underwent a hybrid procedure involving endovascular repair of the aneurysm with a right-to-left carotid crossover bypass and a left carotid to left subclavian bypass to protect the cerebral and left subclavian blood flow. The caecal tumour was later completely excised by laparoscopic right hemicolectomy. The patient then underwent resection for the liver metastases. There was no evidence of tumour recurrence 2 years after her right hemicolectomy. This case emphasizes the importance of the association of C. septicum infection with colorectal malignancy. To our knowledge, this is the first case of a mycotic aortic arch aneurysm caused by C. septicum being successfully treated with a hybrid endovascular repair procedure.