PIK3CA-Related Overgrowth Spectrum (PROS) are rare syndromes caused by a mutation in the PIK3CA gene, including fibroadipose hyperplasia or overgrowth; congenital lipomatous overgrowth, vascular malformations, epidermal nevi, scoliosis/skeletal and spinal (CLOVES); megalencephaly-capillary malformation (MCAP or M-CM); fibro-adipose vascular anomaly (FAVA); Klippel-Trenaunay syndrome (KT; also known as, Klippel-Trenaunay-Weber syndrome); capillary, lymphatic, and venous malformations (CLVM); and lymphatic malformation (LM). Here, PIK3CA is linked to Klippel-Trénaunay syndrome.