title: The venous nevus: a distinct vascular malformation suggesting mosaicism.
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'.
authors.affiliation: Department of Dermatology, University of Regensburg, Regensburg, Germany. sabrina.zietz@klinik.uni-regensburg.de
authors.forename: Sabrina
authors.initials: S
authors.lastname: Zietz
authors.forename: Rudolf
authors.initials: R
authors.lastname: Happle
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hohenleutner
authors.forename: Michael
authors.initials: M
authors.lastname: Landthaler
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009030:Mosaicism; D009092:Mucous Membrane / Q000473:pathology; D009506:Nevus / Q000235:genetics / Q000473:pathology*; D012878:Skin Neoplasms / Q000235:genetics / Q000473:pathology*; D054079:Vascular Malformations / Q000235:genetics / Q000473:pathology*