Incidental Diagnosis of Hereditary Hemorrhagic Telangiectasia Following Perioperative Hypoxemia in a 4-Year-Old Child.

A 4-year-old girl with no prior respiratory history developed refractory intraoperative hypoxemia during elective dental surgery under general anaesthesia. Despite 100% inspired oxygen and systematic exclusion of all conventional causes of desaturation, pulse oximetry (SpO2) failed to exceed 94%. Postoperative contrast-enhanced chest computed tomography identified a 2.01-cm pulmonary arteriovenous malformation (PAVM) in the right lung, and subsequent molecular genetic testing confirmed hereditary hemorrhagic telangiectasia (HHT). The patient was discharged with baseline SpO2 of 85%-95% on room air and established on long-term paediatric pulmonary follow-up. This case highlights that PAVMs associated with HHT can manifest as unexplained perioperative hypoxemia in asymptomatic children, and that general anaesthesia with positive pressure ventilation may unmask previously compensated right-to-left shunting. Early recognition enables appropriate perioperative management and timely HHT surveillance.