Vascular Complications of Osteochondromas: A Report of Two Cases

Introduction

Osteochondromas, or exostoses, are the most common form of benign bone tumor, representing about 20–50% of all benign and 10–15% of all bone tumors.¹ Patients rarely develop vascular complications. In the English literature, only 106 cases are reported. The development of a pseudoaneurysm, which was first described by Paul in 1953,² is reported in 58 cases.^1,3–7 We report two cases of vascular complications of osteochondromas: a pseudoaneurysm and an arterial occlusion.

Case Report 1

A 22-year-old male with a smoking habit and an HIV infection presented with increasing swelling of the left thigh. A radiograph showed a pedunculated image, which was suggestive of a benign osteochondroma of the distal left femur. For two weeks before admission he had experienced severe thigh pain, numbness of the leg, and limitation to physical activity. On physical examination, a painful, big, and not pulsatile mass in the distal thigh was found. A duplex ultrasound examination of the limb revealed a 13 cm-diameter pseudoaneurysm. This was confirmed by magnetic resonance imaging. Emergency surgery was decided. After having controlled the superficial femoral artery above the pseudoaneurysm, it was opened. A 5 mm transmural hole associated with the exostosis was noted in the anterolateral wall of the popliteal artery. The artery was repaired with a polytetrafluoroethylene (PTFE) patch graft. A distal femur osteotomy was then performed to remove the exostosis. The postoperative period was uneventful.

Case Report 2

A 31-year-old male without prior medical problems presented with osteochondroma in the proximal right tibia bone, which had been known about since adolescence. Three months before, he started to feel pain in this region. On physical examination, peripheral pulses were present. No intermittent claudication was present. The angio-computed tomography showed a tibial osteochondroma and an occlusion of the distal popliteal artery with patency of distal arteries. Surgery was decided. Through a posterior approach in the calf, the popliteal vessels and nerves were controlled. Occluded artery surroundings appeared like they had been bruised. First, a resection of the tibial osteochondroma was made. Then arterial reconstruction was performed with a bypass graft from the distal popliteal artery to the tibioperoneal trunk using the external saphenous vein in reverse. The patient did well postoperatively and was discharged on day 8 after surgery and prescribed rehabilitation exercises. In both cases, the pathologic studies revealed the benign nature of the osteochondroma. The patients remain asymptomatic 24 and 15 months after surgery, respectively.

Discussion

Osteochondromas are the most common benign tumors of the bone, observed in 1–2% of the population.³ They appear during the growth period. They are solitary or included in multiple hereditary osteochondromas pathology condition. When multiple, they represent an autosomal dominant inheritance pattern, and three genes (EXT1, EXT2, and EXT3) have been shown to be involved in its etiology.⁸ None of our patients had medical histories of multiple hereditary osteochondromas.⁶ Osteochondromas are typically asymptomatic bony protuberances first noticed in childhood or adolescence. There is a large predominance of men (4:1). It is made up of hyperplasic bone arising from subperiostal displacement of adjacent epiphyseal plane cartilage. The cartilage cap of this tumor is soft and pliable, but it ossifies at the end of the growth period. They are commonly stalk-like or sessile in appearance. The primary location of the osteochondromas is the lower limb, with predominance of the lower metaphysic part of the femur.¹ They are commonly revealed on plain radiographs in the case of pain or minor motion limitation, which is often the consequence of neurologic compromise, bursa formation, growth abnormality, or malignant degeneration, which occurs in less than 4% of the osteochondromas that are treated with surgical procedures. Vascular complications are rare. We have reviewed the English literature, and only 106 cases of vascular complications in exostoses have been published.^1,3–7

Patient symptoms depend on the location and size of the tumor and on the type of vascular injury. The most common complaint was a hard swelling for a long time. The development of pain could be the consequence of fracture or vascular compression. Clinical examination revealed a pulsatile or nonpulsatile mass, distal ischemia, phlebitis, and unilateral limb swelling or paresthesias. In the case of direct trauma, the osteochondromas were broken and had perforated the surrounding vessel. Some repetitive exercises, such as knee flexion, could chronically abrade the popliteal artery and produce an adventitial defect followed by a false aneurysm. Approximately 1:3 patients with vascular complications had a medical history of direct trauma or vigorous exercise before hospital admission. The primary location with osteochondromas involved in vascular complications was the lower limb, with a predominance of the lower metaphysic part of the femur. Arterial damage represents nearly 90% of vascular complications. False aneurysm is the most frequent lesion in more than 60% of cases. Isolated vein lesions have also been described (compression or thrombosis). Other symptoms can be intermittent claudication or acute ischemia.⁶ The tests available to study exostoses are a plain radiograph, a pulsed duplex scan, an angiography, a computed tomography scan, and a magnetic resonance imaging scan. These last two help in diagnosing false aneurysms, and they are also able to establish anatomic relationships with the surrounding tissues. Surgical treatment of vascular complications of osteochondromas is recommended.

Prophylactic resection of osteochondromas in the vicinity of a vessel must be performed. Arterial injury has been repaired with primary suture of the arterial defect, vein or PTFE patch angioplasty, resection with end-to-end anastomosis, vein grafting, or interposition PTFE grafting. In acute ischemia in situ fibrinolysis with urokinase and distal thrombectomy has been described.^1,3–6 Wong et al have reported transarterial embolization using microcoils in the treatment of osteochondroma-related pseudoaneurysm of the superficial femoral artery before subsequent semielective surgery.⁷ In our first case, because of the defects’ diameter and arterial vasospasm, no primary repair could be realized. We did a PTFE patch angioplasty, but a vein patch could also be done. In the second case, because of the chronic occlusion, a bypass was necessary. Concomitant excision of the exostosis is recommended (leaving the remaining bone even) to prevent future vascular injury. It is important to remove the perichondrium, along with the base of the tumor and the perichondrium surrounding it. Recurrence of an osteochondroma is rare, but has been reported. Therefore, postoperative follow up with imaging tests is recommended.⁴

Conclusions

Vascular complications of osteochondromas are uncommon. Vasseur and Fabre propose surgical resection of osteochondromas if it is in the vicinity of a vessel, if there is a risk of interference with a joint, if there is a fracture in the osteochondroma, or if there is suspicion of malignant transformation.⁶