A case of Mycobacterium intracellulare pleurisy without active lung lesion

Pleural effusion without occurrence of active pulmonary lesion due to nontuberculous mycobacteria is extremely rare. We report a case of Mycobacterium intracellulare pleurisy in an 84-year-old woman. The patient was admitted to a nearby hospital because of dyspnea. Massive right pleural effusion was observed on chest roentgenogram. Bacteriological examinations, smear and culture of the sputum or pleural effusion were negative. First we thought pleurisy was caused by M. tuberculosis as pleural effusion showed predominant lymphocyte count and high adenosine deaminase level. However, M. intracellulare was identified by the polymerase chain reaction method from pleural effusion. Based on clinical findings and laboratory data, we suspected pleurisy was due to M. intracellulare infection. Clarithromycin, kanamycin, rifampicin and ethambutol were administered. After four months of treatment pleural effusion disappeared without accompanying the active pulmonary lesion. Therefore, we diagnosed this case as pleurisy without pulmonary lesion due to M. intracellulare.