A 51-year old man, who was an ex-smoker, was admitted in August 2003 with two months' history of productive cough and an episode of haemoptysis. There was no history of fever, loss of weight or appetite. He had similar complaints five years ago which were successfully treated with antibiotics. He denied having any contact with tuberculosis patients. Clinical examination was unremarkable except for minimal crepitations at the base of the left lung. Upon admission, the patient's full blood count, renal and liver function tests were within normal limits. His erythrocyte sedimentation rate was 21 mm/h and random blood sugar was 11.4 mmol/l. Subsequently, fasting showed that his blood sugar level was normal. Three consecutive sputum samples were negative for acid-fast bacilli. Sputum for bacterial culture did not grow any organism. Chest radiograph showed a thinwalled cyst in the left lower lobe with an air-fluid level and surrounding pneumonic changes (Figure 1a).