Empyema means the presence of pus in the pleural space between the outer surface of the lung and the chest wall. Empyema can occur as a complication of tuberculosis, pneumonia, trauma, repeated aspiration of pleural fluids and also following various chest operations.

However, in advanced cases which have been on medicines for several months with a thick hard layer around the lung, surgery is mandatory to be able to remove the disease completely as incomplete removal of the pus and the peel, often leads to recurrence of the disease process later.