(a) Lesion on leg, cheek, hand, and tongue of patients #11, 19, 13, and 4, respectively. All have the L914F mutation. (b-e) Immunohistochemical staining of sections of dysmorphic vessels and surrounding areas, from VM of patient # 15, with L914F. (b) Smooth muscle alpha-actin demonstrates variable smooth muscle cell layers, thin (arrow) and thick (arrowhead). (c) TIE2 stains a continuous, thin layer of endothelial cells (ECs), shown at higher magnification (boxed) in (d) and (e). TIE2 expression is not detected outside endothelial cells. (f, g) Double-mutant TIE2 alleles in patients with multifocal VMs. (f) Patient #27: large buttock-VM at birth, appearance of small (<1 cm diameter) lesions (round, hyperkeratotic when on plantar surface) by age 6; [Y897F + R915L] TIE2 cis double-mutations in both buttock and foot lesions. (g) Patient #28: multiple (sub)cutaneous and intramuscular lesions in the face, thorax and abdominal regions, with new lesions appearing by age 18. Tongue and wrist VMs, both with [Y897C + R915C]. Normal allele, blue; mutant, red.