[Mycobacterial infection within a pulmonary bulla]

The patient was a 31-year-old man. Chest X-ray films and computed tomographic (CT) scans disclosed fluid retention within an 11-cm diameter pulmonary bulla that had been detected in the upper lobe of his left lung 1 year earlier. CT films also disclosed a 1.5-cm nodular lesion in the apical segment of the left lower lobe. The patient had no symptoms and laboratory examinations disclosed no signs of inflammation. Thoracoscopic examination revealed a yellow-turbid fluid with caseous necrosis within the bulla. Although Ziehl-Neelson staining of a bulla tissue specimen was 1 on the Gaffky scale, culture of the fluid was negative. Histologically, the bulla wall and pulmonary nodule revealed granuloma with caseous necrosis, thus yielding a diagnosis of mycobacterial infection within the bulla and lung. Following an operation, anti-tuberculous drugs were administered and the patient was well without recurrence of tuberculosis 30 months afterward. We concluded that infectious bulla with few or no symptoms and limited inflammatory findings may occasionally be caused by Mycobacterium infection.