Evaluation and management of the lateral marginal vein in Klippel-Trénaunay and other PIK3CA-related overgrowth syndromes.

The lateral marginal vein is an anomalous clinical entity found in association with Klippel-Trénaunay and other PIK3CA-related overgrowth syndromes. Although it is reported to affect <20% of patients with Klippel-Trénaunay syndrome, this venous anomaly has been associated with significant morbidity and mortality attributable to venous hypertension and potentially lethal thromboembolic events. Limited literature exists on the diagnosis and management of this rare anomaly, with most of the reports focusing on retrospective clinical experience at a few centers of excellence. Despite these limitations, a systematic approach to diagnosis and treatment of this anomaly is warranted and expounded on herein. When plausible, clinical recommendations based on best available literature are made.