Vascular Malformations Diagnosis And Treatment

Overview

Vascular malformations are abnormal blood vessel changes which occur before birth and during blood vessel development. They may only be discovered later in life, and are most commonly found in the head or neck, but can be seen anywhere in the body, varying in size and presentation. A vascular malformation can affect the capillaries, veins, arteries or lymphatic system. Untreated vascular malformations result in poor prognosis, so early diagnosis is essential to enable early treatment and prevent further development. Vascular malformations can often increase in size due to triggers such as hormones and trauma. Due to the complexity of vascular malformations, patient diagnosis and treatment require a multidisciplinary team approach, including vascular surgeons, nurses, radiologists, ultrasound practitioners and plastic surgeons amongst others. 

This article will discuss the diagnosis of vascular malformations, such as medical examination, different imaging techniques and biopsy. The treatment options will also be detailed, such as conservative, minimally invasive and surgical techniques. The prognosis and long-term follow-up of these patients will also be described. 

Types of vascular malformations

Classification of vascular malformations is based on the vessels involved, which can include malformation of capillaries, veins, the lymphatic system and arteries and veins combined. 

Capillary malformations 

Capillary malformations are composed of dilated capillaries with slow blood flow, located in the superficial layers of the skin. Capillary malformations are notably presented as a ‘port wine stain’, where there is a discolouration of regions of the skin, often appearing dark red. The lesions often appear without any identifiable cause, but genetic mutations such as in the RASA1 gene have been linked to some inherited cases of capillary malformations.¹ They can also be associated with other genetic conditions such as Klippel-Trenaunay syndrome and Sturge-Weber syndrome, which can also include soft tissue or skeletal abnormalities such as leg-length discrepancy.² The cause of these lesions is unknown, however, studies into the cells have shown poor functioning of nerves, which could possibly affect the control of vascular flow in the region. 

Venous malformations

Venous malformations are the most common vascular malformations and involve abnormal development of the veins. Clinical presentation involves soft compressible regions with blue skin discolouration and an absence of pulsation of redness.³ Venous malformations can occur in any tissue, including skin, muscle, bone, and internal structures, and on imaging can appear as a cluster of veins. There is slow blood flow within venous malformations, which can lead to blood clot formation. Most cases of venous malformation occur with no clear cause, although rare cases have been associated with mutations in the TIE-2 receptor gene, which has a role in vascular development.¹

Arteriovenous malformations

Arteriovenous malformations are a connection between arteries and veins and occur most commonly in the head and neck region.  They disrupt normal blood flow and oxygen circulation, bypass nutrient exchange and shunt blood directly into the venous system.⁴ Fast blood flow is seen within arteriovenous malformations, due to the involvement of high pressure of blood from the arterial system. The connection can be directly between one artery and one vein, which is termed an ‘arteriovenous fistula’, or can consist of many smaller abnormal connections, called a ‘nidus’. Arteriovenous malformations are composed of thick-walled arteries and veins which have developed thicker walls due to the high pressure of blood flow.¹ 

On clinical assessment, arteriovenous malformations present a palpable pulse, or ‘thrill’, and have serious clinical implications, such as bleeding and cardiac (heart) failure.² Studies have shown links between the genes of the RAS pathway, which encode proteins involved in cell signalling.² 

Lymphatic malformations

Lymphatic malformations consist of channels of lymphatic fluid which causes abnormal lymphatic flow. Lymphatic malformations clinically present non-pulsatile localised swelling, red or brown skin discolouration and severe pain, with recurrent infections in the region.² These malformations occur most commonly in the head and neck and therefore can lead to problems with swallowing. 

Diagnosis

Diagnosis of vascular malformations can rely on taking a patient history and identifying symptoms before carrying out a physical examination of the areas. As the different types of malformation present slightly differently, the symptomatic regions must be carefully assessed. 

Ultrasounds

One imaging technique that can help with diagnosis is an ultrasound, which is inexpensive and non-invasive. Ultrasounds involve moving a probe over the skin which sends and receives high-frequency sound waves. Colour Doppler can also be used, which can show the movement of fluid, allowing for assessment of blood flow. 

On ultrasound examination of vascular malformations low or slow flow can be seen, along with clusters of compressible veins spreading throughout the layers of tissue. Capillary malformations are similar in appearance, but closer to the surface of the skin. Arteriovenous malformations display as high speed blood flow, with enlarged veins.⁵ 

Magnetic resonance imaging (MRI)

Magnetic resonance imaging (MRI) is a non-invasive modality which uses magnetic fields to map out the structures of the body. For assessment of vascular malformations, contrast MRI helps to map out the vascular regions. MRI can be particularly useful in cases of venous malformation with bone involvement.⁵

CT scan

Computed tomography (CT) scan is a non-invasive imaging type that utilises X-rays to image the body. CT scanners consist of a rotating X-ray tube with a row of detectors, and contrast can also be used to assess the arteries and veins.⁵ 

Angiography

Angiography can also be used, which involves using X-rays and contrast agents to highlight the blood vessels.⁵ 

Biopsy

Biopsy is rarely used to diagnose vascular malformations, but can be used if imaging techniques fail to produce a diagnosis.⁵ 

Symptoms associated with venous malformations can also be indicative of other conditions, such as varicose veins, which can appear as swollen, compressible, blue-discoloured regions. Additionally, soft tissue and vascular tumours can be mistaken for vascular malformations. 

Treatment options

Conservative management

Conservative management involves observation of vascular malformation lesions over time, to monitor any changes in size or symptoms. In the cases of venous and lymphatic malformations, compression stockings may lead to improved lymphatic and venous drainage and a decrease in the lesions’ volume. Compression can also help to provide pain relief, limit swelling, and reduce the risk of ulcer development.¹ 

Sclerotherapy can be used for venous malformations, which involves the injection of a foam solution into the regions to block the veins. 

Minimally invasive options

Minimally invasive procedures for the treatment of vascular malformations can include embolisation, which is a way of blocking abnormal blood vessels using X-rays and wires. 

Laser therapy can also be used, which uses lasers to induce damage to the inner lining of the blood vessels, causing them to clot and block off. Radiofrequency ablation has the same effect but uses radiofrequency waves.

Surgery

Surgical intervention can involve the removal of the malformations through excision, but there is a risk associated with this as poor visualisation of the tissues and bleeding can lead to surgical injury of other tissues. 

Microsurgical excision is a technique that involves using a microscope and microsurgical instruments to allow for precise control of small structures. A microsurgical approach may minimise injury to the surrounding area and preserve blood supply.⁶

Combination therapy 

Combination therapy can involve sequentially trying the different treatment options and assessing symptom improvement at different stages. Beginning with conservative management, and moving to minimally invasive, and then surgical options can be a useful method of treatment. Additionally, treatment of these patients requires good communication between a multidisciplinary team of doctors, surgeons, nurses and other healthcare professionals. 

Complications and prognosis

Potential complications of vascular malformations can include thrombophlebitis, where superficial veins become blocked and inflamed. Additional complications include bleeding, pain and impairment of function, which can affect bones and joints along with tissue. Patients with vascular malformations in the head and neck report lower quality of life due to visibility of lesions and negative impact on sleep.⁷ 

The location of vascular malformations can have an effect on prognosis. Arteriovenous malformations located in the brain are prone to rupture and are responsible for 25% of haemhorragic strokes in adults under fifty years of age.⁸ Rupturing of brain arteriovenous malformations can be fatal, or can result in lifelong disability. 

Even after surgical treatment, it is possible for vascular malformations to reoccur, which happens more often in children than adults.⁹ Post-operative and regular surveillance imaging is useful in helping to detect recurrence. Regular follow-ups with the medical team to monitor any developing symptoms or lesions are important to prevent further development of vascular malformations. 

Summary

In summary, vascular malformations are complex and serious, and successful treatment involves the contribution of a multidisciplinary team. The treatment and management can depend heavily on the location of malformation and the type, such as capillary, venous, arteriovenous or lymphatic. Diagnosis can include medical examination and imaging techniques, with ultrasound, CT, MRI and angiography playing major roles in identifying the type and size of lesions present. Treatment can range from conservative, to minimally invasive and surgical options, with the most effective method often including a sequential combination of all three. Complications and prognosis depend on the lesion present, so individualised treatment plans are essential for the best outcome.