Venous malformations (VMs) are characterized by vein wall defects due to vascular dysmorphogenesis caused by the lack of smooth muscle cells. As a result, the veins become enlarged, with impaired blood circulation (
VM can be clinically diagnosed when it is present at birth or when the lesion shows characteristic morphological features of bluish skin discoloration. Superficial and localized lesions without specific symptoms or signs that indicate treatment may not require imaging studies. In cases of symptomatic or extensive lesions, Doppler ultrasono-graphy (US), computed tomography, and magnetic resonance imaging (MRI) or magnetic resonance venography (MRV) are the preferred methods for the initial diagnosis of VMs and post-treatment follow-up (
Lower-extremity venous duplex examinations are generally performed with a linear array transducer using high frequencies of 9∼12 MHz. Because ultrasound examination of VMs does not document reflux, it can be performed with the patient in the supine position. However, standing or reverse Trendelenburg positioning may facilitate examina-tion by dilating the veins. These positions are also useful when reflux needs to be evaluated, as in patients with Klippel–Trenaunay syndrome, characterized by VM and varicosities. When the lesion is visible superficially, the area around the suspected lesion can be observed. If the lesion is extensive, the deep and superficial veins of the affected limb should be examined. Sonographic techniques include a combination of grayscale, color Doppler, and spectral wave Doppler examinations. Once the echotexture, borders, and size of the lesion are measured with gray-scale imaging, color Doppler and spectral wave Doppler examinations are performed to document the flow characteristics within the lesion. When VM is associated with Klippel–Trenaunay syndrome or other phosphatidy-linositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-related overgrowth syndromes, marginal veins can be observed from the lateral aspect of the leg. The marginal vein is a valveless anomalous vein that charac-teristically lacks fascial encasements (
The margin and size of the lesion can be measured on gray-scale examination. Appearances of the lesions range from purely solid to multicystic and localized and from well-defined to infiltrative or cavitary (most common) dysplastic (
Experience is required to image VMs in order to accurately diagnose and provide all measurements necessary to guide treatment. If the ultrasound report is inadequate or incomplete, an MRI/MRV examination should be performed. The person who performs the imaging should be familiar with any potential limitations related to his/her experience and those of ultrasound. Some cases that may be helpful for physical examination and ultrasound assessment are also presented.
A 33-year-old woman presented with a long-standing history of a large mass on the right lateral foot with increased swelling and pain on palpation (Fig. 1). She had a history of occasional pain with palpation or ambulation, particularly with prolonged standing, and no history of venous thrombosis or trauma. She underwent sclerotherapy for the mass in 2000. Ultrasound B-mode imaging revealed multiple dilated veins on the lateral aspect of the foot (Fig. 2A). The lesion extended from behind the lateral malleolus to the base of the toe. The diameters of the veins varied from 1 to 6 mm. On color flow imaging, slow flow was observed in multiple veins and the flow was augmented by distal compression (Fig. 2B). Spectral Doppler waveform also revealed slow flow (Fig. 2C).
On MR, a large, complex, low-flow VM along the lateral aspect of the ankle and foot was observed, which insinuated within the intermuscular fat of the flexor compartment (Fig. 3). The lesions were markedly hyperintense on the T2- weighted images.
Other imaging features of VM can be observed in images obtained from various patients. Fig. 4 shows an anterior shin mass in a 56-year-old man (Fig. 4A). This patient had a hard mass that had not regressed or increased in size for many years. Ultrasound B-mode imaging showed multiple dilated veins in the subcutaneous space (Fig. 4B-D). No spontaneous flow was observed on color flow imaging (Fig. 4E).
Fig. 5 shows anterior and anterolateral thigh VMs. A 39-year-old man presented with a dilated vein in the thigh and symptoms of swelling and pain (Fig. 5A). Ultrasound B-mode imaging showed multiple dilated veins in numerous locations of the subcutaneous and intramuscular spaces (Fig. 5B-D). On color flow imaging, short reflux was seen in multiple veins using distal compression with sudden release (Fig. 5E). On spectral Doppler imaging, slow flow was observed (Fig. 5F), which was augmented with low intensity by forceful distal compression (Fig. 5G).
Table 1 summarizes the differences between VM and VV. First, the etiologies of the two diseases are different. VM is congenital and usually occurs at birth. In some cases, where VM is not recognized at birth, it often presents as a mass that does not regress on its own for many years. VM can occur anywhere in the body. VV is caused by reflux in the lower extremities and appears relatively late in life. Both types of disease can appear as dilated hypoechoic tubular structures on B-mode imaging; however, VM can be found at various depths, including subcutaneous, intramuscular, or even within the bone. VMs exhibit much slower flow than VVs. Reflux can be observed in VMs. However, even if reflux is found in a VM, the intensity is low, and the duration is short, unlike the reflux seen in VVs.
Differential diagnosis of venous malformation (VM) and varicose vein (VV)
|Shape||Dilated vein||Dilated vein|
|Extent||Localized, extensive||Localized, extensive|
|Flow||Stagnant flow||Normal venous flow|
|Reflux||Low intensity||>0.5 sec|
Ultrasonography is an excellent method for the diagnosis and follow-up of patients with VM. The imaging features of VM are distinct and easy to recognize using ultrasound. Experience is necessary to understand most VM patterns and provide an accurate diagnosis to help plan treatment. When there is limited experience with ultrasound or the exam is inadequate, and in cases with extensive complex VMs, MRI/MRV should be performed.