Klippel-Trenaunay syndrome: a single-center experience with combined slow-flow vascular malformations

Abstract Background Klippel-Trenaunay syndrome (KTS) refers to a combination of capillary malformation + venous malformation ± lymphatic malformation + limb overgrowth. In this report, we present a case series of combined slow-flow vascular malformations (KTS) managed at a multidisciplinary vascular anomalies clinic. Results The study included 26 patients diagnosed as having combined slow-flow vascular malformations (KTS) during the period 2015 through 2024. The age at presentation ranged between 1 month and 15 years (mean = 35.9 months; median = 24 months). Eighteen out of the 26 patients were males (69.2%). Except for three cases, the lower extremities were always involved, whether unilateral, bilateral, or in conjunction with other regions in the body (commonly the lower trunk, abdomen, and pelvis). All cases presented with asymmetrical and distorted body contour. Other common complaints included pain and bleeding from skin lesions. Conservative management was the mainstay of treatment. Laser ablation, injection sclerotherapy, and/or surgery were used in selected cases to manage symptoms. Sirolimus was an effective medical treatment to control recurrent bleeding from diffuse skin lesions and mucous membranes. Alpelisib, a direct PI3K inhibitor, holds promising potential in the future treatment of KTS; however, it has not yet been used in our current patient cohort. Marginal vein should be treated by surgery or endovascular occlusions if deep veins are not absent. Conclusion Klippel-Trenaunay syndrome is a combination of slow-flow vascular malformations mostly occurring in the lower extremities with tissue overgrowth. The venous anomalies (lateral marginal vein) represent the primary source of complications and should be treated after ruling out abnormalities of the deep venous system. Localized symptomatic lesions may be treated with targeted interventions such as surgical excision, injection sclerotherapy, or laser ablation. Sirolimus is a systemic medication with promising outcomes in the treatment of such cases with complex and diffuse anomaly.