Similar pleural fluid findings in pleuropulmonary tularemia and tuberculous pleurisy.

Biochemical and cellular characteristics of pleural fluid from two patients with pleuropulmonary tularemia and 39 patients with tuberculous pleurisy were compared. High pleural fluid concentrations of adenosine deaminase, lysozyme, and beta 2-microglobulin occurred in both diseases. As is the case with tuberculous pleural effusions, pleural fluid in tularemia showed an abundance of lymphocytes, predominantly CD4-positive T lymphocytes. The similar pleural fluid findings suggest analogous local pathogenetic mechanisms in tularemia and tuberculosis. In the diagnostic evaluation of a lymphocyte-rich exudative pleural effusion with a high adenosine deaminase concentration, a possible cause to consider is tularemia.