SESSION TITLE: Plueral Cases
SESSION TYPE: Affiliate Case Report Slide
PRESENTED ON: Monday, October 26, 2015 at 11:00 AM - 12:00 PM
INTRODUCTION: Non-tuberculous mycobacteria (NTM) were first described after Robert Koch’s discovery of tuberculous bacilli in the late 19th century. They are commonly occurring organisms and have been recovered from a variety of environmental reservoirs. Pleuritis and pleural effusions are included under rare and atypical presentations accounting for 5-15% of pulmonary mycobacterium avium complex (MAC). Primary MAC pleuritis without MAC infection is extremely rare.
CASE PRESENTATION: 52 year old smoker with emphysema presented with complaints of right sided chest pain and 20 pound weight loss over 2 months without fever, cough or sputum production. Chest x-ray showed right lower lobe infiltrate with effusion. Given concern for malignancy and tuberculosis he underwent bronchoscopy with bronchoalveolar lavage with biopsies from the right lower lobe. Cultures and cytology from BAL were negative. Biopsies were negative for malignancy as well. He also underwent thoracentesis and pleural studies revealed an exudative effusion. Human immunodeficiency virus(HIV) antibody was negative. Pleural fluid culture eventually grew out MAC. The patient was started on treatment with rifabutin, ethambutol and azithromycin. A year later he presented with persistent effusion requiring chest tube placement for drainage, repeat cultures did not show MAC. He was followed in clinic and had resolution of effusion with evidence of trapped lung.
DISCUSSION: The exact mechanism of pleuritis caused by MAC is unknown. It is possible that MAC gains entry to a pleural cavity containing an effusion of unrelated etiology through a transient bacteremia or by contiguous spread from a small subpleural focus and may grow in the pleural fluid without eliciting any readily discernible pathologic reaction. Other potential causes include malnutrition, impaired cellular immunity, disrupted microvascular circulation due to diabetes mellitus and surgical procedures. The presence of pre-existing lung disease like emphysema is an important factor in attaining infection as seen in our case.
CONCLUSIONS: Pleural effusions caused by MAC in an immunocompetent host are rare and can be a diagnostic challenge. A high index of suspicion and culturing effusions of unknown etiology are needed to make a diagnosis.
Reference #1: C Zheng, CH Fanta. Non-tuberculous mycobacterial pulmonary infection in the immunocompetent host. Q J Med 2013; 106:307-315
Reference #2: K Yanagihara, K Tomono, T Sawai, Y Miyazaki, Y Hirakata, J Kadota, S Kohno. Mycobacterium Avium Complex Pleuritis. Respiration 2002; 69:547-549
DISCLOSURE: The following authors have nothing to disclose: Pooja Desa, Ketan Buch
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