Dad 81yr has pulmonary tb & on med since a month.tests rule out malignancy.why is fluid building up after being drained.is having difficulty breathing?

TB extraplural: Tuberculous pleural effusion is one of the more common forms of extrapulmonary tuberculosis (TB). This problem may co exist with presence of pulmonary involvement by the mycobacterium. The cause of the effusion is a delayed hypersensitivity response to the TB antigens in the pleural space. Pleural fluid adenosine deaminase (ADA) levels greater than 40 U/l argue strongly for TB .