Growing blood clot mimicking an aneurysm on postoperative computerized tomography and magnetic resonance imaging studies - Case report and review of the literature

The authors describe the case of a 15-year-old boy who underwent resection of a large left temporal tumor. During a normal postoperative course, compu terized tomography (CT) scanning demonstrated a spherically hyperdense stru cture near the internal carotid artery, enlarging on a control CT scan. A s uspected false aneurysm was confirmed on magnetic resonance imaging; angiog raphic studies were negative. The authors believed they were dealing with a thrombosed false aneurysm and they performed operative revision. Intraoper atively the "aneurysm" could be dissected off the internal carotid artery a nd no lesion of the arterial wall was obvious. Histological findings showed a fresh blood clot. This case demonstrates that a blood clot may mimic an aneurysm on CT and magnetic resonance studies, which has not been described earlier. The origin of the blood clot remains unclear.