Delayed posttraumatic pseudoaneurysm of the anterior tibial artery mimicking a malignant tumor.

The anterior tibial artery arises at the lower border of the popliteus muscle, and passes anteriorly to lie on the interosseous membrane medial to the fibular neck. Injury to the artery results in extravasation of blood, and the tamponade effect of the surrounding tissue may contain acute hemorrhage. The blood clot gradually liquefies resulting in the formation of a fibrous capsule. Consequently, a pseudoaneurysm contains no normal elements of arterial wall, as opposed to a true arterial aneurysm. Pseudoaneurysm of the anterior tibial artery has been reported as a complication of fracture surgery and is usually felt to be iatrogenic. It has occurred following a fracture treated without surgery and may be related to the vessel being tethered by the fascia and interosseous membrane. It has also been reported in cases of blunt trauma to the leg without fracture, and as well following elective orthopedic procedures. We report the case of a patient 7 months following open reduction and plate fixation of a fracture of the distal third of the tibial shaft, who presented with a large painful proximal leg mass thought to be a malignant tumor. Three previous such presentations have been found in the literature and illustrates the importance of suspecting a delayed vascular injury following lower leg trauma. Duplex ultrasound examination should be performed initially to avoid an inadvertent incision and catastrophic bleeding as might occur with an inappropriate biopsy. Preoperative and intraoperative angiograms are essential to confirm the diagnosis, delineate the site and type of injury, and help to plan the treatment.