[Case of tuberculous pleurisy distinguished from pleurisy caused by Mycoplasma infection]

We report a case of tuberculous pleurisy that required differentiation from pleurisy caused by Mycoplasma infection. A 28-year-old woman presented to a clinic with fever and pain on the left side of her chest. A chest radiograph revealed pleural effusion in the left thorax, and the condition was diagnosed as bacterial pleurisy. The patient was referred to our hospital because of an increase in the pleural effusion despite antibiotic treatment. Mycoplasma infection was suspected because the patient was young, the white blood cell count was not elevated, and the result of the ImmunoCard Mycoplasma test (IC) for Mycoplasma pneumoniae-specific IgM antibodies was positive. However, the fever persisted even after treatment with azithromycin and pazufloxacin. The left pleural effusion was exudative, with lymphocytosis and high adenosine deaminase (ADA) levels. The results of the QuantiFERON test were positive. Therefore, tuberculous pleurisy was diagnosed, and the effusion subsided after treatment with standard anti-tuberculosis chemotherapy. Although detection of Mycoplasma infection using the IC is rapid and simple, the accuracy of this test is poor. The patient was first diagnosed with pleurisy of Mycoplasma origin because of a single high-particle agglutination titer of 1: 320 and because of the presence of exudative pleural effusion with lymphocytosis and elevated ADA levels, which has been reported in patients with Mycoplasma infection. The results of the IC test and the ADA level of the pleural effusion might not be reliable when distinguishing between tuberculous pleurisy and pleurisy caused by Mycoplasma infection.