Hereditary vascular malformations featuring the presence of small, multifocal bluish-purple venous lesions involving the skin. May be present at birth, and slowly expand during childhood. New small lesions appear with time. Often painful on palpation and cannot be completely emptied by compression. They are usually multifocal and are located mainly on the extremities, involving the skin and subcutis. Caused by mutations in the gene encoding glomulin and inherited in an autosomal dominant manner.