40 year old male farmer who has livestock was admitted with paroxysms of cough and expectoration. Clinical examination was normal. Chest X-ray showed a large thin walled cavity containing membranes in the lower lobe of the left lung with left pleural effusion. CT scan of the chest revealed a 'water lily' sign. What is the most probable diagnosis?
Echinococcus infection
Aspergillosis
Interstitial lung disease with TB
Amebic lung abscess
Water lily sign although rarely seen is pathognomonic of echinococcosis. Cyst with a freely floating endocyst.