Mycotic Aneurysm of the Common Carotid Artery as a Presenting Symptom for Early Colorectal Malignancy.

Mycotic carotid aneurysms are rare vascular conditions that are associated with high mortality if left untreated. We present a gentleman who had a progressively enlarging tender pulsatile swelling on the right side of neck. Emergency computed tomography scan showed a large mycotic aneurysm arising from the right common carotid artery, and he underwent emergency open exploration with interposition bypass graft. Bacteroides fragilis species, which signified gastrointestinal-related sepsis, was isolated from the thrombus culture. Subsequently search of systemic septic source showed an early rectal adenocarcinoma. This is the first case in the world's literature of a patient who had B. fragilis mycotic carotid aneurysm as a presenting complaint of his occult rectal malignancy.