n rteriovenous Malformation in the Suprapatellar Fat Pad of the Knee associated with Klippel-Trenaunay- Weber Syndrome: Case Report 1 Mi Hyun Park, M.D., Soon Tae Kwon, M.D., yung Seok Shin, M.D., Young Mo Kim, M.D. 2 Klippel-Trenaunay-Weber syndrome (KTWS) is a vascular disorder that has significant arteriovenous malformation (VM). We report a case of an VM in the suprapatellar fat pad of the knee in a patient with the characteristic manifestations of KTWS, including cutaneous hemangioma, limb hypertrophy, and varicose veins. Magnetic resonance imaging, color Doppler sonography, and subsequent angiography demonstrated an VM in the supra-patellar fat pad of the right knee causing painful swelling of the knee. Index words : Extremity, arteriovenous malformation rteriovenous malformation, MR rteriovenous malformation ngiography Klippel-Trenaunay-Weber syndrome (KTWS) is a rare congenital disorder characterized by cutaneous hemangiomas, hypertrophy of bone and soft tissue, varicose veins, and clinically significant arteriovenous malformation (VM) (1, 2, 3). VMs associated with KTWS are located in the extremities, visceral organs, or spinal canal (1, 3). Most VMs in the extremities are intramuscular or cutaneous. There is a paucity of data on VMs in the suprapatellar fat pad associated with KTWS. We report imaging findings of a case with VM in the suprapatellar fat pad of the right knee associated with KTWS. Case Report 25-year-old man presented with a three-month-long 1 Department of Diagnostic Radiology, Chungnam National University Hospital 2 Department of Orthopedic Sugery, Chungnam National University Hospital Received July 11, 2005 ; ccepted September 7, 2005 ddress reprint requests to : Soon Tae Kwon, M.D., Department of Diagnostic Radiology, Chungnam National University Hospital, 640, Daesa-dong, Jung-gu, Taejon 301-040, Korea. Tel. 82-42-220-7333. Fax. 82-42-253-0061 27 history of painful swelling in the right knee. There was knee joint swelling but change in skin color or bruising. spirated fluid from the knee joint was bloody. There was no specific family history of congenital disease. Physical examination revealed a brown spot on the right leg, which was apparent at birth, and a cutaneous hemangioma in the right shin and ankle. The right leg was slightly longer than the left on physical examination and the plain radiograph of lower extremity (Fig. 1). The right iliac and femoral artery was also greater in diameter than the left on femoral arteriogram (Fig. 2). lower extremity venogram showed dilated and tortuous superficial varicose veins in the right ankle and leg (Fig. 3). There was no thrombosis in the venous system based on both venography and ultrasonography. venous Doppler sonogram showed severe venous reflux in the right superficial femoral vein, as well as a popliteal vein due to valvular incompetence. There were multiple dilated tortuous vascular channels in the supra-patellar fat pad on gray-scale and color Doppler sonograms (Fig. 4). We obtained an arterial Doppler spectral waveform within a vessel with spectral
analysis. MR imaging showed numerous signal voids in the supra-patellar fat pad, in axial T1, sagittal proton density, and T2 weighted spin-echo images (Fig. 5). MR imaging also demonstrated large amounts of joint effusion and thick intrapatellar plica (Fig. 5). selective femoral arteriogram showed a dilated tortuous feeding artery and early enhancement of an enlarged draining vein and nidus, indicating VM (Fig. 6). most frequently affects the lower extremities, but can affect the upper limb, trunk, and head (2, 4). The cause of KTWS is still not clear. One hypothesis proposed an intrauterine insult during vascular differentiation, with subsequent invasion of the developing limb bud, and other proposed a congenital mesodermal ab- Discussion Klippel-Trenaunay syndrome is characterized by cutaneous hemangiomas, hypertrophy of bone and soft tissue, and varicose veins. When a clinically significant VM is noted in addition to this triad, the syndrome is termed Klippel-Trenaunay- Weber syndrome (13). Klippel-Trenaunay syndrome is usually unilateral and Fig. 1. Plain anterior posterior radiograph of the leg shows that the right leg is longer than the left. Fig. 3. Venogram in the distal leg shows diffuse dilatation of the deep venous system, including distal tibial vein. Note.- varicosity of the distal posterior tibial vein (arrows) Fig. 2. Femoral arteriogram showing greater diameter of the right iliac () and femoral artery () than the left. 28
J Korean Radiol Soc 2006;54:27-31 Fig. 4.. Longitudinal US image at the suprapatellar area of the right knee demonstrates several anechoic tortuous vascular channels in and around the suprapatellar fat pad (asterisk), mainly projecting into the suprapatellar bursa.. The same scan of a color Doppler US image reveals numerous enlarged vessels. Fig. 5. xial T1 weighted SE image () (TR/TE, 700/12) and T2 weighted spinecho image () (TR/TE, 2000/20, 2000/80) shows numerous signal voids (arrows) in the suprapatellar fat pad, mainly projecting into the distended suprapatellar bursa. There was large amount of joint effusion and thick intrapatellar plica in the right knee. C Fig. 6.. Femoral angiogram shows an abnormal dilated feeding artery (arrows) originating from the right femoral artery.. Superselective arteriogram shows a dilated and tortuous feeding artery (arrows) and nidus (arrow heads) in the early arterial phase. C. Superselective arteriogram shows early draining vein (arrows) with dilated and tortuous feeding artery and nidus in arterial phase. 29
normality (1, 4). Recently erry et al proposed the involvement of a somatic mutation for a factor critical to vasculogenesis and angiogenesis in embryologic development (2). Hemangioma in KTWS are usually located in the skin of the lower extremity, but it can extend deeper to subcutaneous tissue, muscle, bone, and visceral organs, which may lead to internal hemorrhage (3, 5). Limb hypertrophy develops later in life. It is usually due to subcutaneous tissue hypertrophy, but can associate with bone hypertrophy, which results in leg length discrepancy. leg length discrepancy of over 1.5 centimeters requires orthopedic correction (2). KTWS has several other osseous manifestations, such as syndactly, polydactly, and congenital hip dislocation (1). superficial varicosity of the affected limb is a characteristic finding in KTWS. KTWS patients often have deep venous malformations, such as aplasia, hypoplasia, duplication, or abnormal venous valve formation. There is also significant reflux in normal veins. Deep venous malformation is an important factor in deciding to operate on a superficial varicosity. n operation for superficial varicosities is contraindicated in patients with abnormalities of the deep venous system, so venography and Doppler sonography are performed to evaluate the deep venous system (1, 2, 4, 5). In our case, no deep venous malformation was observed, but there was significant reflux in the deep venous system. VMs are rare congenital vascular lesions characterized by an abnormal connection between arteries and veins. rterial blood is shunted to the venous system in a central confluence of tortuous vessels, called a nidus. The VMs are congenital and they do not involute (6, 7). Clinically significant VMs are an essential finding for KTWS diagnosis (13, 5). In KTWS, the VMs are located in the extremities, visceral organs, or spinal canal (3). The VMs associated with KTWS may be single or multifocal in the extremity, or they may be diffuse and involve the entire extremity and adjacent trunk (1, 3). VMs in the extremities are usually intramuscular or cutaneous. This is the first report of KTWS-associated VMs in the suprapatellar fat pad that caused painful swelling of the knee joint and hemarthrosis (17). VMs are usually diagnosed with multiple imaging modalities, which demonstrates a hypervascular lesion with a large feeding arterial vessel (7). Non-invasive imaging modalities such as MR imaging and Doppler sonography can be used for diagnosis of VMs. On MR 30 imaging, the VMs appear as a tangle of multiple signal voids, usually without focal discrete soft-tissue mass. The lesions can also be associated with surrounding edema or fibrofatty stroma (7). Doppler sonography of VMs shows a high velocity, low resistance waveform (6, 7). rteriography demonstrates a dilated tortuous feeding artery, nidus, and an early draining vein (6, 7). We confirmed the presence of VMs by MR imaging, duplex ultrasonography, and angiography. MR imaging showed multiple signal voids around the suprapatellar fat pad, and a Doppler sonogram with spectral analysis demonstrated vessels with arterial waveform, high velocity, and a decreased resistive index in the knee joint. Femoral angiography showed a typical VM in the knee joint. Most complications of KTWS are related to the underlying vascular pathology, such as pain, bleeding, thrombosis, or pulmonary thromboembolism. bnormal vessels in gut, kidney, or genitalia can cause severe bleeding (2). In particular, the VMs dilate progressively with age and can result in both local and systemic complications. Local complications are pain, bleeding, tissue ulceration, and impairment of limb function. VMs can also cause cardiac overload, resulting in heart failure (6, 7). In our case, the chief complication of VM was painful swelling of the knee joint. There was no color change or bruising, which is usually noted in extremity VMs. We did not suspect vascular malformation after physical examination because of its location in the suprapatellar fat pad. Repeated aspirations of knee joint fluid during follow up were bloody, so we hypothesized that VM caused a hemarthrosis. Treatment of KTWS is conservative and symptomatic (13). For VMs, surgery is extremely difficult and total removal is rarely possible. Superselective transarterial embolization is the most effective treatment for VMs (6, 7). In summary, an VM associated with KTWS, although rarely located in the suprapatellar fat pad, may cause joint pain and hemarthrosis. References 1. RY Kanterman, PD Witt, PS Hsieh, D Picus. Klippel-Trenaunay syndrome: imaging findings and percutaneous intervention. JR m J Roentgenol 1996;167:989-995 2. erry S, Peterson C, Mize W, loom K, Zachary C, lasco P, et al. Klippel-Trenaunay syndrome. m J Med Genet 1998;79:319 3. my eth Goldman. Heritable disease of connective tissue, ephiphy-
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