No abstract

Background: Venous malformations are common vascular anomalies which only occur sporadically. Objective: We present a series of 25 patients with extratruncular venous malformations of the skin or the neighboring mucosa that are arranged in a segmental pattern. Results: All lesions were sporadic and mostly unilateral. According to the extent of the vascular malformation, two subgroups were defined: large- to medium-sized and small localized lesions (‘acrofacial distribution’). In large- or medium-sized lesions, we noted a strict midline separation of the disorder. Thus, we assume that this segmental arrangement reflects genetic mosaicism. Conclusions: This type of venous malformation originates from a postzygotic mutation that occurs at an early developmental stage. Hence, the type of vascular disorder present in our 25 patients seems to fulfil each criterion of the term ‘nevus’. This vascular nevus should be distinguished from other forms of venous malformations such as the varicose veins associated with the Klippel-Trénaunay syndrome, the dermal nodules of the blue rubber bleb nevus syndrome and the vascular skin lesions of the Maffucci syndrome. Thus, we propose the new term ‘venous nevus’ or ‘nevus venosus’.