[Venous malformations: clinical characteristics and differential diagnosis]

Venous malformations (VM) are localized defects of blood vessels that are due to vascular dysmorphogenesis. These slow-flow lesions can affect any tissue or organ. Clinically, a cutaneous VM is characterized by a bluish mass that is compressible on palpation. Phleboliths are commonly present. Symptoms depend on location and size. VM are often sporadic and isolated, however, they can be associated with other malformations and be part of a syndrome; Klippel-Trenaunay (capillary-lymphatico-venous malformation with limb hypertrophy) is the most common. Glomuvenous malformation (GVM) is another type of venous anomaly. In contrast to VM, GVM is often painful on palpation and not compressible. Clinical diagnosis of VM is often made in the presence of a bluish cutaneous lesion: however, other lesions can mimick VM. The most frequent anomalies are a blue naevus, a hemorrhagic lymphatic malformation, a sub-cutaneous hemangioma or even the presence of dilated superficial normal veins due to underlying venous stenoses. This chapter will detail the clinical characteristics of venous anomalies and their differential diagnosis.