Mycotic pseudoaneurysm in the external carotid artery from Escherichia coli.

A 78 year-old women presenting at the Emergency Department with a painful, palpable tumour in the left mandibular angle of one month’s evolution. She had no history of trauma, surgery or regional infection. Intravenous contrast computed tomography revealed a collection of 5.2 cm in the left carotid space, with a thick wall with high uptake (Fig. 1: arrows), gas in its interior and with no communication with the skin or oropharynx, compatible with an abscess. This purulent collection encompassed the carotid vessels which are permeable (Fig. 2: carotid arteries. (A) External; (B) internal), but with an aneurysmatic dilatation of 1.5 cm affecting the ostium and at the origin of the ipsilateral external carotid artery (Figs. 1--3), with no extravasion of contrast. The abscess was compressing the internal jugular, leaving its lumen filiform but not thrombosing it. Antibiotherapy was instituted and surgery to drain the abscess and ligate the left external carotid artery. A great proliferation of Escherichia coli (E. coli) was obtained from culture of the purulent material, as a single germ. The case described is a mycotic pseudoaneurysm in the left external carotid artery due to E. coli, with an associated abscess in the ipsilateral carotid space.