Left maxillary artery pseudoaneurysm: a rare and late postoperative complication after head and neck cancer treatment

Abstract

We report a case of a 50-year-old man presented with pulsatile swelling in the left side of the face since 2 months and a continuous sinus discharge since 3 days. Three years earlier, he was operated for squamous cell carcinoma (SCC) of the left lower alveolus and underwent surgical excision with myocutaneous flap reconstruction, followed by chemoradiotherapy. CT angiogram of the expansile swelling revealed pseudoaneurysm of third part of the left maxillary artery and treated by surgical intervention.

Background

Vascular complications after head and neck cancer surgery usually are haemorrhage, thrombosis, pseudoaneurysm and arteriovenous fistula.¹ Delayed presentation of maxillary artery pseudoaneurysm (with a discharging sinus) in a patient who has undergone head and neck cancer treatment (surgery followed by chemoradiotherapy) has not been reported to the best of our knowledge. The delayed presentation is also unusual. There was no history of trauma or any recent surgery in that area. The common aetiology of pseudoaneurysms of the maxillary arteries is post-traumatic mandibular fractures.² In our patient, no cause could be detected, and we have to presume that it is a case of late onset disruption in the arterial wall and may be related to irradiation. The ideal treatment is percutaneous embolisation and rarely surgery. In this case, the pseudoaneurysm was complicated with sinus formation and added infection hence surgical excision of the clots and ligation of the feeding vessel were necessary.

Case presentation

A 50-year-old man presented to us with a pulsatile swelling on the left face since 2 months and consequently developed a sinus 3 days prior to presentation, discharging blood-stained fluid. Three years earlier, he was operated for squamous cell carcinoma (SCC) of the left lower alveolus and underwent left hemimandibulectomy with therapeutic neck dissection and pectoralis major myocutaneous flap reconstruction followed by chemoradiotherapy. All treatments were completed 2 years ago. He had no symptoms or comorbid illnesses. He was on regular follow-up, and there was no evidence of carcinoma recurrence. He has facial asymmetry (postsurgery) and a healthy flap. Inspection revealed a 5×3 cm swelling over and below the left zygomatic arch (figure 1), with expansile pulsations (video 1). There was local rise of temperature, slightly tender and inflamed. Systolic bruit was heard on auscultation and there was no continuous murmur. A 0.5 cm diameter sinus discharging (pulsatile) serosanguinous fluid and sometimes blood was noted in the inferior aspect of the swelling. Systemic examination did not reveal any other significant findings.

Figure 1.

A swelling of 5×3 cm, superficial to and below the left zygomatic arch (yellow arrows), 0.5 cm sinus at the anteroinferior aspect of swelling (blue arrow).

Video 1

Video clip showing the pulsatile nature of the swelling.

Investigations

Routine blood parameters were within normal limits. X-ray of the skull showed no erosion of zygomatic arch. Contrast-enhanced CT (CECT) scan sagittal and coronal section images (figures 2 and 3) clinched the diagnosis, and leak was visualised from the left maxillary artery at the distal part, rest of the swelling, which was non-enhancing, was due to organised clots.

Figure 2.

Axial CT angiogram section showing the origin of superficial temporal branch (white arrow) of left external carotid artery just proximal to the pseudoaneurysm (black arrow) arising from the left maxillary artery, surrounded by eccentric non-enhancing isoattenuating soft-tissue mass consistent with thrombus (yellow arrows).

Figure 3.

Coronal CT angiogram section shows: fusiform pseudoaneurysm arising from left maxillary artery (single thick arrow) surrounded by eccentric non-enhancing isoattenuating soft-tissue mass consistent with thrombus (double arrows), left external carotid artery.

Differential diagnosis

Arteriovenous malformation (AVM), haematoma, abscess, angiofibroma and parotid mass.

Treatment

The patient was taken up for emergency aneurysm ligation. The incision started at the lower part of the left zygomatic arch anteriorly going backwards towards the tragus of the left pinna and downwards into the upper part of the neck up until the mid sternocleidomastoid muscle. There was dense adhesion due to prior radiation and therefore it was decided to directly open the aneurysmal sac. The clots were removed and the rent sutured with 5-0 monofilament suture. Next the area was dissected and the feeding vessel found out and ligated which was the proximal maxillary artery. (figure 4).

Figure 4.

Intraoperative digital image shows the ligated left maxillary (single arrow), excised thrombus shown in the inset.

Outcome and follow-up

Postoperative recovery was uneventful. On discharge, the sinus was still raw and required daily dressing for 2 weeks for healing to occur and later the patient was symptom free and doing well on follow-up after 1 month.

Discussion

A pseudoaneurysm is a haematoma that forms as the result of a rent from an artery due to direct trauma or postoperative injury, where the arterial wall gets partially damaged. Another aetiology is due to a near by prosthesis or metal rod, where the artery pulsation continuously abuts against the metal. Common cause is iatrogenic trauma^2–4 whenever dissection near an artery partially injures the arterial adventitia or even deeper into the media of arterial wall and later leads to disruption of the vessel wall. The infective aetiology of pseudoaneurysms like mycotic aneurysms has been reported.⁵ The natural pathophysiology of pseudoaneurysm starts from the arterial leak which leads to haematoma formation and persists until the pressure in the haematoma is large enough to counterbalance the arterial pressure and tamponade the area by the surrounding tissues. By this tamponade effect the further arterial flow is diminished. Meanwhile, the haematoma turns into a clot, retracts and the central portion liquefies in seven or more days followed by the formation of endothelial lined continuity with the vessel wall owing to the pulsatile nature of the pseudoaneurysm.⁴ Externally, the haematoma forms a false vascular wall (pseudocapsule). This pseudocapsule may rupture and cause haemorrhage.

The clinical diagnosis of a pseudoaneurysm is based on the history of trauma or surgery to the involved region and subsequent development of a pulsatile mass, which gradually increases in size. They usually present within weeks to months of injury,⁶ even they may present as late as 6 months to 3 years after initial injury.⁷ Our patient gives neither history of trauma nor any intervention post surgery, which might cause arterial injury, and there is no history suggestive of infection. Hence we attribute the aetiology to either trauma during previous surgery which has manifested very late or postirradiation.⁸ The chance of maxillary artery injury during extensive surgery appears remote as already 3 years have passed. Irradiation is a strong possibility which could have weakened the arterial wall due to radiation induced arteritis and resulted in the aneurysm. Radiation therapy affects all sizes of blood vessels within the field of treatment. Degeneration of the endothelium, vacuolisation and thickening of the intima associated with changes in the elastic fibres have been described in the radiated arteries of humans. However, vascular occlusion is the most common form of presentation.⁹ These changes manifest as early as 4 months or as late as 23 years after radiotherapy.¹⁰ Since then, Thomas and Forbus¹¹ published the first report of radiation injury to blood vessels; literature review shows many numbers of similar reports of radiation-induced vasculopathy.

Formation of aneurysm as a complication of radiation therapy in various sites like iliac artery,¹² arteries of circle of Willis,¹³ carotid artery¹⁴ have been reported. Similarly, there are several reports of pseudoaneurysm of the external carotid artery following radical neck dissection and irradiation.¹⁵ The patient received a total of 60 Gy radiation doses, and it was 2 years ago.

The expansile pulsation immediately points towards the diagnosis of aneurysm. For final confirmation other tests are required. Duplex scan is a non-invasive technique and clinches the diagnosis; the laminar thrombosis and the size of the leak area can be measured but it provides little information about the soft tissues and osseous structures adjacent to the lesion. Magnetic resonance angiography is non-invasive but expensive and it can highlight the soft tissue abnormality and its relationship to the adjacent soft tissues. Turbulent flow within a pseudoaneurysm could result in intervoxel dephasing, which could underestimate the size of the lesion or overestimate the amount of thrombosis.¹⁶ There are several advantages with CT angiography like it can assess the patency and position of the vessels, true size of the pseudoaneurysm is accurately depicted, relationship with the osseous structures are clearly shown. In our case, AVM has been ruled out as there was no evidence for asymmetric early venous drainage.

The maxillary artery is one of the larger terminal branches of the external carotid artery and is divided into three parts, mandibular, pterygoid and pterygopalatine. It arises below the temporomandibular joint and enters posterior to neck of the mandible, and through the substance of the parotid gland, it passes forward between the ramus of the mandible and the sphenomandibular ligament and then runs, either superficial or deep to the lateral pterygoid muscle, to the pterygopalatine fossa. It supplies the inner structures of the face. The third part of the maxillary artery was involved in our case.

Treatment of the pseudoaneurysm usually depends on its severity, characteristics and the health status of the patient hence the treatment should be individualised.¹⁷ Options available are non-invasive (prolonged manual compression) for very small aneurysms and at superficial areas and invasive (percutaneous embolisation, surgical excision or both). In percutaneous embolisation, metallic coils, polyvinyl alcohol particles and absorbable gelatine sponge are used by occlusion where they convert a pseudoaneurysm into a haematoma, the later gets reabsorbed in due course. Surgical exploration and excision are undertaken when conservative or percutaneous embolisation have failed. However, pseudoaneurysms with local signs of infection are best treated surgically.¹⁷ Our patient underwent surgical excision and has fully recovered.

Learning points .

• Iatrogenic pseudoaneurysm of arteries can present in a delayed fashion contrary to their common early presentation.

• Proper clinical examination can differentiate vascular lesions from more common lesions like abscesses particularly at an operated site to avoid torrential bleeding.

• Irradiation can lead to weakness in the arterial wall leading to complications.

• A level of suspicion of occult vascular injuries is required in patients with unilateral facial swellings following mandibular surgeries even after years after the procedure was recommended.