Multiple cutaneous and mucosal venous malformations

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Multiple cutaneous and mucosal venous malformations (also known as VMCM) is a condition that affects the skin (cutaneous) and the moist tissues that line body cavities (mucous membranes), such as the mouth and nose. Affected individuals develop bluish patches (lesions) that represent areas where the underlying venous blood vessels developed abnormally (venous malformations). These lesions can be painful, especially when they extend from the skin into the muscles and joints.

Blood in venous malformations moves slowly, which can cause clots to form. Slow blood flow and clotting within the malformation can cause pain, swelling, and inflammation. Over time, some blood clots may harden (calcify) to form nodules called phleboliths, which can sometimes be felt underneath the skin. In people with VMCM, medical evaluation and management may be needed during pregnancy or before surgical procedures to reduce the likelihood of abnormal clotting or bleeding episodes.

Most people with VMCM are born with at least one venous malformation. As affected individuals age, the lesions that are present at birth usually become larger and new lesions often appear. The size, number, and location of venous malformations vary among affected individuals, even among members of the same family.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Genetic changes that cause disease or increase the risk of disease are called pathogenic variants. Pathogenic variants in the TEK gene can predispose individuals to develop venous malformations. The TEK gene provides instructions for making a type of protein called a receptor tyrosine kinase. The TEK receptor triggers the release of chemical signals that are needed for forming blood vessels (angiogenesis) and maintaining their structure. This signaling allows communication between two types of cells found within the walls of blood vessels: endothelial cells and smooth muscle cells. Communication between these two cell types is necessary to direct angiogenesis and to maintain the structure and integrity of blood vessels.

The pathogenic variants in the TEK gene that are associated with VMCM cause the TEK receptor to become overactive. Excessive signaling disrupts the normal growth and organization of endothelial cells and their interactions with the surrounding smooth muscle cells. As a result, venous blood vessels may develop abnormally, leading to the venous malformations seen in people with VMCM.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

VMCM is inherited in an autosomal dominant pattern, which means one altered copy of the TEK gene is sufficient to predispose individuals to develop venous malformations. Affected individuals typically have a parent with VMCM.

Evidence suggests that the inherited variant in the TEK gene may not always be enough to cause a particular venous malformation to develop; approximately 10 percent of people who inherit a pathogenic TEK variant do not develop visible signs of the disorder by age 20. In people with VMCM, an additional pathogenic variant in the TEK gene may arise during a person's lifetime and be present only in certain cells. This type of variant is called a somatic variant. Because the somatic variant only occurs in certain cells, it may help explain why venous malformations develop in different areas of the body and why their number and location vary among affected individuals.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

VMCM appears to be a rare disorder, although its exact prevalence is unknown.

Which doctor should you see?

The suggested department for discussing Multiple cutaneous and mucosal venous malformations is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Multiple cutaneous and mucosal venous malformations. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.