Gastrointestinal involvement in Klippel-Trénaunay syndrome: pathophysiology, evaluation, and management.

Klippel-Trénaunay syndrome is typically a complex combined capillary-lymphatic-venous malformation in lower limb. Gastrointestinal involvement is not infrequent in Klippel-Trénaunay syndrome. Rectal bleeding is the most common complication. In recent years, this condition has been increasingly reported. However, most authors simply described extreme manifestations or various combinations of clinical observations. The underlying pathophysiology of gastrointestinal involvement in Klippel-Trénaunay syndrome has been underrecognized. Pathophysiologically, some seemingly adequate managements are pitfalls in treatment. Anorectosigmoid vascular malformations in KTS have distinct and more complicated pathophysiologies than anorectal vascular malformation. Once understanding the pathophysiology, some patients can be successfully managed with a staged plan in our practice. Therefore, recognizing the pathophysiologies of gastrointestinal involvement is needed to evaluate, prevent pitfalls, and determine adequate managements for practitioners. Because of the complexity and rarity of this condition, prospective controlled study or a large cohort of patients is impossible. Based on literature review and our practice, we discuss pathophysiologies, evaluation, pitfalls, and treatment strategies for gastrointestinal involvement in Klippel-Trénaunay syndrome.