The blue man who presented with a stroke

A 19-year-old man presented with sudden onset of right eye ptosis, diplopia and giddiness. He had no previous medical illnesses with negative history of exertional dyspnoea, epistaxis, haemoptysis, palpitations, chest pain and chronic cough. Examination revealed central cyanosis, digital clubbing, polycythaemia, partial ptosis of right eye, diplopia on right gaze and dilated right pupil. Examination of the chest revealed pectus excavatum but no cardiac murmurs were heard. Investigations revealed a solitary right pulmonary arteriovenous malformation with two feeder vessels which were successfully embolized surgically.