Glomuvenous malformations (GVM) result from improperly formed veins in the layers of the skin and deeper tissues. GVMs are bluish-purple marks or bumps that are usually confined to the skin, but sometimes extend to the deeper layers of fat or muscle. They commonly appear near fingers or toes, but are also seen on the inside of the mouth and eyelids and other skin locations. These malformations vary in size and may enlarge over time. They generally do not affect internal organs. GVMs can be variable in extent, remaining very localized in some cases, and affecting entire limbs in others.
There are two types of glomuvenous malformations: solitary and multiple. Solitary GVMs are more common and often painful. Multiple GVMs account for 10 percent of reported cases and usually develop earlier in life. Gloumuvenous malformations are hereditary in 65 percent of patients and have been linked to a mutation in the "glomulin" gene.