De novo brain vascular malformations in hereditary hemorrhagic telangiectasia

Objective Approximately 10% of people with hereditary hemorrhagic telangiectasia (HHT) have brain vascular malformations (VMs). Few reports describe de novo brain VM formation or VM growth. International HHT Guidelines recommend initial brain VM screening upon HHT diagnosis in children but do not address rescreening. We aimed to confirm whether brain VMs can form de novo in patients with HHT. Methods The BVMC HHT project is a 17-center longitudinal study enrolling patients since 2010. We analyzed the database for de novo VMs defined as those detected 1) on follow-up neuroimaging in a patient without previous brain VMs or 2) in a location distinct from previously identified brain VMs and reported those in whom a de novo VM could be confirmed on central neuroimaging review. Result Of 1909 patients enrolled, 409 (21%) had brain VMs. Seven patients were recorded as having de novo brain VMs, and imaging was available for central review in four. We confirmed that three (0.7% of individuals with brain VMs) had de novo brain VMs (2 capillary malformations, 1 brain arteriovenous malformation) with intervals of six, nine, and 13 years from initial imaging. Two with de novo brain VMs were <18 years. The fourth patient, a child, did not have a de novo brain VM but had a radiologically confirmed increase in size of an existing brain arteriovenous malformation. Conclusion Brain VMs can, albeit rarely, form de novo or grow in HHT patients. Given their potential risk of hemorrhage, regular rescreening in patients with HHT may be warranted.