The term KTS has been used to denote a combination of CM+VM +/- LM + limb overgrowth. It is not a genomically uniform diagnosis. Many severe cases are due to somatic pathogenic variants in PIK3CA and are now recognized as part of the PIK3CA-related overgrowth the diagnosis of diffuse capillary malformation with overgrowth (see DCMO). Other cases with overgrowth and vascular birthmarks in association with higher flow vascular anomalies fit best as “Parkes Weber syndrome”, a separate diagnostic entity. Note: The term Klippel-Trenaunay-Weber syndrome is not correct. It has had moderately widespread use in the pediatric literature, after it appeared in some textbooks, but it is a mixture of two distinct syndromes, Klippel-Trenaunay and Parkes Weber and should not be used spectrum (PROS). Other cases which mimic the definition of KTS are due to GNAQ/GNA11 somatic pathogenic variants and most often best fit with [missing copy here].