A previously well 47-year-old woman presented with a 4-week history of non-productive cough and lethargy without weight loss, orthopnoea or exertional dyspnoea. She was normotensive and a non-smoker.

Clinical examination was unremarkable, and no lymphadenopathy was detected. Routine blood tests including inflammatory markers were normal. The electrocardiogram showed sinus rhythm with non-specific T …