Hereditary haemorrhagic telangiectasia and pulmonary arteriovenous malformations.

Hereditary haemorrhagic telangiectasia (HHT) also known as Osler-Weber-Rendu syndrome is an autosomal dominant disorder affecting 1 in 8000 individuals. The eponym recognises the 19th-century physicians William Osler, Henri Jules Louis Marie Rendu and Frederick Parkes Weber who each independently described the disease. It is characterised by epistaxis, telangiectasia and visceral arteriovenous malformations. Individuals with HHT have been found to have abnormal plasma concentrations of transforming growth factor beta and vascular endothelial growth factor secondary to mutations in ENG, ACVRL1 and MADH4. Pulmonary artery malformations (PAVMs) are abnormal communications between pulmonary arteries and veins and are found in up to 50% of individuals with HHT. The clinical features suggestive of PAVMs are stigmata of right to left shunting such as dyspnoea, hypoxaemia, cyanosis, cerebral embolism and unexplained haemoptysis or haemothorax. The authors present the case of a 33-year-old woman presenting with progressive dyspnoea during the COVID-19 pandemic. She had a typical presentation of HHT with recurrent epistaxis, telangiectasia and pulmonary arteriovenous malformations. Although rare, PAVM should be considered in individuals presenting to the emergency department with dyspnoea and hypoxaemia. Delayed diagnosis can result in fatal embolic and haemorrhagic complications.