Pulmonary tuberculosis with unusual cystic change in an immunocompromised host

We present a rare case of upper zone cystic change of the lung with disseminated tuberculosis of a non-smoking 30-year-old immunocompromised male. He suffered from repeated pneumothorax. The basic pathological feature of video-assisted thoracoscopic lung biopsy revealed granulomatous involvement in the respiratory bronchioles with poorly developed epithelioid cells and disruption of elastic fibers. Electron microscopy demonstrated a decrease in elastic fibers and disruption of the epithelial basement membrane of the respiratory bronchiole and no Langerhans cells in the lesion. Autopsy of the lung revealed centroacinar distribution of multiple cystic lesions in the bilateral upper lobe. Almost all cystic walls showed loss of elastic fibers and cysts frequently involved the respiratory and terminal bronchioles, alveolar ducts and, occasionally, alveoli. Some larger cystic lesions revealed communication to the bronchi. The cystic changes in this case of pulmonary tuberculosis may be caused by a check-valve mechanism due to granulomatous involvement of the bronchioles and also by excavation of caseous necrotic material by draining bronchi.