Mucocutaneous venous malformations (ORPHA:2451)
Mucocutaneous venous malformations (VMCMs) are hereditary vascular malformations characterized by the presence of small, multifocal, bluish-purple venous lesions involving the skin and mucosa.
Epidemiology
Prevalence is unknown but around 20 families have been identified so far.
Clinical description
The multifocal venous lesions are usually small (< 2cm in diameter), and are present at birth. They are soft and usually compressible and undergo proportionate growth with age. There is significant clinical variation with respect to the size, location and number of lesions, even between affected individuals from the same family. Classically, one individual in a given family has a large lesion. Small lesions are usually asymptomatic, whereas larger lesions can cause pain and invade subcutaneous muscle. New lesions appear with time. Patients with VMCMs have normal mental and physical development.
Etiology
VMCMs are associated with amino acid substitutions (R849W and Y897S) in the tyrosine-protein kinase endothelial cell receptor (TEK/TIE2; 9p21). Approximately 90% of individuals who have a mutation in the TEK gene develop mucocutaneous venous malformations by 20 years of age; conversely, approximately 10% of individuals with a TEK mutation are clinically unaffected.
Diagnostic methods
Diagnosis is based on clinical evaluation of the cutaneous lesions. Doppler ultrasound examination can be used to confirm slow blood flow, and MRI can be used to confirm the venous component and extent of the lesions. Ultrasound examination reveals saccular compressible venous-like cavities. Molecular genetic testing for confirmation of the diagnosis is available on a research basis.
Differential diagnosis
The differential diagnosis should include glomuvenous malformations (GVMs, which are deeper purple in color than VMCMs, painful on palpation, and more superficial than venous malformations; see this term) and Blue rubber bleb nevus syndrome (characterized by the association of cutaneous and mucosal venous-like lesions with gastrointestinal lesions; see this term).
Antenatal diagnosis
Prenatal diagnosis is feasible for affected families in which the disease-causing mutation has been identified, but is not widely available.
Genetic counseling
VMCMs are transmitted in an autosomal dominant manner with incomplete penetrance. Paradominant inheritance (presence of a germline mutation and a somatic mutation) appears to be involved in disease expression and may explain the variability in clinical phenotype. Genetic counseling should be provided for affected families, informing patients of a 50% risk of inheriting the disease-causing mutation and of the variability in clinical expression. There is no anticipation in reported families.
Management and treatment
The principle treatment approach is sclerotherapy, alone or in combination with plastic and reconstructive surgery depending on the size and location of the lesions. Ethanol (96%) for injection is the most commonly used sclerosing agent and obtained EU orphan drug designation in April 2005 for the treatment of congenital venous malformations. When D-dimers are elevated, indicating activation of coagulation, low-molecular-weight heparin can be used to treat the associated pain. Female patients should avoid using oral contraceptives with high estrogen levels.
Prognosis
The prognosis for patients is good, malignant transformation has not been reported and the life expectancy for patients is not reduced.

                            Last update: 
                            January 2009


                            - Expert reviewer(s): 
                            Pr Laurence BOON  - Pr Miikka VIKKULA