An 86-year-old woman had been diagnosed with rheumatoid arthritis 4 years prior to this case, and was prescribed prednisolone 5 mg + salazosulfapyridine 500 mg per day. Here, she presented to the Department of Rheumatology with fatigue, non-productive cough for 7 days, and fever for 3 days. She had no hemoptysis, night sweats, weight loss, or chest pain. She also reported no recent history of exposure to illness or hospitalization. The patient's vital signs were stable on admission. Chest auscultation revealed reduced breath sounds in the right lower zones. Laboratory investigations revealed an elevated level of C-reactive protein (6.61 mg/L) without leukocytosis. Interferon-gamma release assay (T-SPOT .TB; Oxford Immunotec, Oxford, United Kingdom) results were positive. Chest radiography showed dullness of the right costophrenic angle, while computed tomography scan of the chest revealed right pleural effusion with right lower lobe compressive atelectasis (Fig. 1A and B). Pleural fluid biochemical analysis revealed that the pleural fluid protein/serum protein ratio was 0.78, with a pleural fluid lactate dehydrogenase level of 784 U/L, indicative of an exudate according to light criteria. The pleural fluid glucose level was 101 mg/dL, which was within normal range. Pleural fluid differential cell count showed predominant lymphocytosis and a high adenosine deaminase level (151.6 IU/L).
Sputum cultures demonstrated no bacterial growth and smears were negative for the presence of acid-fast bacilli. Rheumatoid pleuritis or tuberculous pleurisy was suspected and the patient was transferred to the Department of pulmonology for further examination. Before microbiological tests on pleural fluid were completed, and in an effort to attain a definitive diagnosis for early treatment, thoracoscopy was performed by semi-rigid pleuroscopy under sedation with local anesthesia.
Thoracoscopic findings showed diffuse dissemination of micronodules on the parietal pleura and fibrin adhesions between the visceral and parietal pleura (Fig. 1C). Pleural cryobiopsy was performed by using a 1.9-mm cryoprobe (ERBECRYO, ERBE, US) and the target area of the parietal pleura was frozen for 6 seconds (Fig. 1D).
Specimens obtained from the cryoprobe are shown in Fig. 2A and B: these exhibited the size of 0.9 cm; microscopic findings demonstrated 200-300-mum caseating and non-caseating epitheloid cell granulomas with Langerhans type giant cells. The Ziehl-Neelsen stain for acid-fast bacilli was positive. Based on the above results, the patient was diagnosed with TB pleurisy; due her use of immunosuppressants, anti-tuberculosis treatment was planned for 10 months. At the most recent outpatient follow-up, she had completed 6 months of treatment and was clinically in good condition. Chest radiography showed regression of the pleural effusion, and her clinical course was consistent with our diagnosis.