Park-Weber syndrome (PWS) is a complex congenital vascular malformation syndrome, first reported by Weber in 1907, also known as vasodilatory hypertrophy syndrome, which is characterized by hypertrophy of the affected limb, superficial varicose veins, cutaneous vascular nevus (KTS triad), and arteriovenous fistula. This syndrome is rare and easily confused with congenital arteriovenous malformation (CAVM) and congenital venous malformation (KTS). In addition to the corresponding clinical symptoms of congenital arteriovenous fistula, this syndrome also has symptoms of bone and soft tissue hypertrophy, skin wine discoloration, and varicose veins, which are quite similar to KTS. In the clinical literature, PWS is more often classified as a type of KTS, called Klippel-Trenaunay-Weber syndrome, or Klipple-Trenaunay-Parkes-Weber syndrome. since the 1980s, it has been gradually recognized that PWS and KTS have significant differences in terms of hemodynamics, pathophysiology, clinical manifestations, treatment and prognosis. The etiology of PWS is not well understood and is generally thought to be related to abnormal fetal germ layer development, often accompanied by other congenital lesions of the mesoderm, such as visceral hemangioma and fibromatosis. Recently, some scholars have found that some PWS cases have chromosomal abnormalities and a genetic predisposition. The age of PWS at the onset of obvious clinical symptoms ranges from 4 to 12 years, with an average of 8.2 years. The typical clinical manifestations are: 1. Increased skin temperature. This means that the skin temperature of the affected limb is higher than that of the healthy side. 2. The affected limb grows swollen. It usually occurs right after birth and gradually worsens. This is due to accelerated arterial blood flow stimulating excessive bone hyperplasia and hypertrophy of the muscles and soft tissues of the affected limb. 3. varicose veins. The degree of varicose veins is significantly related to the extent and size of the fistula and the duration of the disease. The varicose veins are often located medially or widely distributed in the lower extremities, unlike KTS; at a later stage, due to obvious lower extremity stasis, they can cause lower extremity hyperpigmentation and stasis ulcers. 4. Skin changes. Large wine colored spots on the affected limbs, often on one side of the limb, may also be distributed on both sides of the trunk. 5. Congenital arteriovenous fistula. In childhood, the angiogram often shows dilated arteries or dense areas of patchy vessels. When adolescence or pregnancy occurs, or after trauma or inappropriate surgical treatment, the lesion often accelerates in expansion. Localized tissue may become necrotic due to “blood theft”, and in severe cases, congestive heart failure may occur. Amputation of the limb is often the end result if there is significant functional impairment or recurrent ulcerative infections. Notably, all affected limbs are free of vascular murmurs and pulsating masses, which helps to differentiate them from other types of congenital arteriovenous fistulas and arteriovenous malformations. The initial diagnosis of PWS is not difficult to make based on the history and signs and symptoms of KTS triad with arteriovenous fistula, but the most reliable way to confirm the diagnosis and guide the treatment plan is to perform both an arteriogram and a superior venogram of the affected limb. The diagnosis of PWS should be confirmed in cases of congenital malformations such as hypoplastic or atretic deep veins with distal dilatation and CAVM-like changes on arteriogram or even direct short-circuiting between the arteries and veins of the main stem. Imaging manifestations and features Arteriogram: Arteriogram shows the main site and extent of arteriovenous fistula lesions and the size of the shunt flow and is the main imaging method for diagnosing this disease. For small arteriovenous fistulas, it is often necessary to perform a bilateral step-in arteriogram to compare the abnormal hemodynamic changes in the affected limb. The main radiographic signs of arteriography are: 1) thickening of the arterial trunk and accelerated blood flow in the affected limb; 2) increased, disorganized, and distorted arterial branches, often multiple; and 3) premature capillary development with darker staining at the end of arterial branches and early venous development, but no direct fistulae. Venography: Venography is mainly used for differential diagnosis. patients with PWS have signs such as limb growth, thickening, superficial varicose veins, and wine-colored skin without vascular murmurs and pulsatile masses, which are easily confused with KTS. In this case, phlebography has a differential diagnostic value. phlebography of PWS can show dilated and distorted superficial venous system, and deep veins are often faint due to accelerated blood flow, but there is no deep vein stenosis, ischemia and abnormally large superficial veins on the outside of the limb, which can be differentiated from KTS. X-ray radiography: The radiograph can show the growth and thickening of the bones of the affected limb, the thickening and layering of the bone cortex, and in some cases, the sparse and disorganized bone trabeculae with small capsular translucent shadow, and the thickening and blurring of the soft tissue. Ultrasonography: in cases of allergy to certain contrast agents or contraindications to contrast, Doppler noninvasive examination is feasible and can be used to make the diagnosis in combination with clinical manifestations. The difference in flow velocity between KTS and PWS is statistically significant for femoral and N veins, but the difference in flow velocity and internal diameter of saphenous vein and the difference in internal diameter of femoral and N veins are not statistically significant. PWS should be distinguished from KTS and CAVM, which are different in terms of hemodynamics, pathophysiology, treatment and prognosis. PWS has both a KTS-like deep venous lesion and a CAVM-like arterial lesion, which is equivalent to a combination of KTS and CAVM, and has a poorer prognosis. Treatment The tiny and widely distributed fistulae in PWS make complete treatment extremely difficult. Only symptomatic treatment is currently available, both to remove the deep venous return obstruction and to remove the arteriovenous fistula. When the epiphysis is not yet closed, epiphyseal suppression can be considered in order to prevent continued skeletal growth causing lower limb claudication. If the epiphysis is closed and the affected limb is distended and painful as the main symptom, elastic bandage or elastic stocking can be used to reduce the symptoms. For those with lower limb ulcers, varicose vein stripping around the ulcer and deep subfascial traffic vein ligation can be done to improve local blood circulation and promote ulcer healing. For adult patients with limited scope, staged segmental arterial ligation of small branches can be performed, and embolic agents can also be inserted into the main blood supply branches of the fistula to improve their clinical symptoms.