Capillary malformation-arteriovenous malformation

Capillary malformation-arteriovenous malformation (CM-AVM) is a rare inherited vascular disorder characterized by the presence of multiple small, round, pinkish-red capillary malformations (CMs) scattered across the skin, often surrounded by a pale halo. These cutaneous lesions are typically present from birth and can be found on the face, limbs, and trunk. A significant proportion of affected individuals—estimated at approximately 30%—also develop fast-flow vascular lesions, including arteriovenous malformations (AVMs) or arteriovenous fistulas (AVFs), which can occur in the brain, spine, skin, muscle, or bone. These fast-flow lesions carry a risk of serious complications such as hemorrhage, heart failure, or neurological deficits depending on their location. CM-AVM is caused by heterozygous loss-of-function mutations in the RASA1 gene (CM-AVM1, also known as CM-AVM syndrome type 1) or the EPHB4 gene (CM-AVM2, CM-AVM syndrome type 2). Both genes encode proteins involved in the RAS/MAPK signaling pathway, which plays a critical role in blood vessel development and maintenance. The condition follows autosomal dominant inheritance with variable expressivity and incomplete penetrance, meaning that family members carrying the same mutation may have very different clinical presentations. Diagnosis is based on clinical findings and confirmed through molecular genetic testing. Management requires a multidisciplinary approach involving dermatologists, interventional radiologists, neurologists, and vascular surgeons. Screening for intracranial and spinal AVMs is recommended, particularly in children, given the risk of life-threatening bleeding. Treatment of AVMs may include embolization or surgical excision depending on the size, location, and symptoms. Capillary malformations themselves are generally benign and may be treated with pulsed dye laser therapy for cosmetic purposes. There is currently no cure, and management focuses on surveillance and treatment of complications.

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