Mechanochemical and surgical ablation of an anomalous upper extremity marginal vein in CLOVES syndrome identifies PIK3CA as the culprit gene mutation

Anomalous marginal veins of the trunk or extremities are congenitally incompetent entities found in association with phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA)-related overgrowth syndromes, such as Klippel-Trénaunay syndrome and congenital lipomatous overgrowth, vascular malformations, epidermal nevi, and skeletal deformities (CLOVES) syndrome. When present, they can be a major source of venous hypertension-related morbidity and potentially lethal thromboembolic events. Herein, we describe a rare case of an upper extremity marginal vein in a patient with CLOVES syndrome. Through a multimodal therapeutic approach, we identified a somatic PIK3CA mutation in the excised anomalous vein. This finding questions the validity of commonly employed terminology, such as persistent embryonic vein, in reference to these anomalous entities.