EPHB4 and cutaneous mastocytosis: Capillary malformation‐arteriovenous malformation (CM‐AVM) syndrome is an autosomal dominant vascular disorder caused by loss‐of‐function variants in either the RASA1 (CM‐AVM1; OMIM: 608354)1 or EPHB4 gene (CM‐AVM2, OMIM: 618196).2