Iliac artery pseudoaneurysm presenting as a paravertebral collection: a potentially fatal mimic.

Pseudoaneurysms of the iliac arteries are extremely rare and can complicate trauma, surgical or interventional procedures. We report a case of pseudoaneurysm arising from the common iliac artery in a 37-year-old man which presented as a paravertebral collection. As the MRI appearance mimicked spondylodiscitis, a CT guided biopsy was requested. However, the presence of a signal void centre guided the radiologist to the correct diagnosis, which was later confirmed on contrast-enhanced CT. Following unsuccessful treatment by percutaneous thrombin injection, open surgery was performed which revealed a leaking aneurysm associated with a huge retroperitoneal haematoma. We present this case to highlight the importance of considering vascular lesions as a differential diagnosis in patients presenting with a mass or pressure symptoms in different parts of the body. Misdiagnosing such lesions as soft tissue tumours or abscesses may result in serious consequences.