PIK3CA and cutaneous mastocytosis: Although they have been historically considered the hallmark of SWS, CMs are also the cardinal cutaneous manifestations of other less frequent and known syndromes, such as Capillary Malformation-Arteriovenous Malformation Syndrome (CM-AVM) (51) and Parkes-Weber syndrome, caused by mutations of RASA1 gene and less commonly EPHB4 gene (54), Macrocephaly-Capillary Malformation Syndrome (M-CM, Figure 8) and Klippel-Trenaunay syndrome (KTS) caused by mutations of PIK3CA, and Proteus syndrome.