Beyond Hereditary Haemorrhagic Telangiectasia (HHT): Capillary Malformation-Arteriovenous Syndrome (CM-AVM)

A woman in her forties, asymptomatic, was referred to the respiratory clinic with suspected HHT due to mucocutaneous telangiectasia involving her face, lips, and hands. Auscultation revealed an audible bruit over her left posterior chest wall.

MRI brain and spine showed no evidence of cerebral arteriovenous malformations. Genetic testing identified a heterozygous EPHB4 splice variant consistent with CM-AVM syndrome. It was negative for mutations associated with HHT.

Red flags indicating pulmonary, intracranial or spinal haemorrhage were explained to the patient. She was linked in with the HHT clinic for routine follow-up and received genetic counselling.

CM-AVM is a rare autosomal dominant vascular malformation syndrome that can clinically mimic HHT but is genetically and phenotypically distinct. It should be considered in patients presenting with mucocutaneous vascular lesions. Genetic testing is essential to guide appropriate surveillance, management, and genetic counselling.