Granulomatous pleuritis caused by Francisella tularensis: possible confusion with tuberculous pleuritis

Granulomatous pleuritis, diagnosed by pleural biopsy, is rarely caused by disease processes other than tuberculosis. We present a case of granulomatous pleuritis caused by Francisella tularensis that occurred in a 55-yr-old male sheep shearer with an exudative, lymphocytic, pleural effusion. Confirmation of the diagnosis was made by elevated serum agglutination titers against F. tularensis and detection of the organism in a pleural biopsy specimen by the glucose oxidase immunoenzyme technique. We conclude that F. tularensis, not previously described as a cause of granulomatous pleuritis, must be considered in the differential diagnosis of granulomas found in pleural biopsy specimens.