Bronchoscopic Visualization of the Alveoli

Abstract

We report a rare case in which we were able to visualize the lung alveoli through the bronchial wall by a bronchoscope in a patient with marked bronchiectasis and performed lung biopsy safely under direct vision. An 80-year-old woman presented with complaints of a severe persistent cough for the past 6 months. A chest computed tomography scan revealed diffuse interstitial pneumonia with marked bronchiectasis. Bronchoscopy also revealed marked bronchiectasis. After inserting the bronchoscope into the 10th-generation bronchus, we observed a honeycomb pattern through the bronchial wall, which represented the alveoli. We perforated the bronchial wall by using biopsy forceps and performed lung biopsy under direct vision. The pathologic diagnosis revealed interstitial pneumonia with epithelioid granuloma and cholesterin-like substance, which were indicative of hypersensitivity pneumonia. The routine performance of true “trans”-bronchial lung biopsy will be possible if a thin bronchoscope with high-quality imaging is developed in the future.

A conventional white light bronchoscope can usually be inserted until the third-generation or fourth-generation bronchus and direct visualization of the bronchus is limited until approximately the fifth-generation bronchus. However, it is common knowledge that the endobronchial tree divides for up to 23 to 24 generations, and direct visualization of the alveolar field is difficult. We report a rare case in which we were able to visualize the alveoli through the bronchial wall at the tenth-generation bronchus by a conventional bronchoscope in a patient with marked bronchiectasis and performed lung biopsy safely under direct vision.

CASE REPORT

An 80-year-old woman presented with complaints of a severe persistent cough for the past 6 months. A chest computed tomography scan revealed diffuse interstitial pneumonia with marked bronchiectasis (Fig. 1). We used a conventional white light bronchoscope with a diameter of 4.9 mm (BF TYPE 260; Olympus Corporation, Tokyo, Japan), and the bronchoscopy confirmed marked bronchiectasis. The bronchoscope was inserted by counting the number of endobronchial divides. No remarkable abnormalities were observed on the endobronchial surface; thus, we presumed that the patient’s bronchus was dilated because of traction from the fibrosis. After inserting the bronchoscope into the tenth-generation bronchus (Fig. Aa), we were able to observe a honeycomb pattern through the bronchial wall (Fig. Ab). We believe that the honeycomb pattern represented the alveoli. We perforated the bronchial wall using biopsy forceps (FB-19C-1; Olympus Corporation), avoiding the vasculature (Fig. 2), and inserted the forceps into the red sponge-like tissue. The punch-biopsy specimen included only the alveolar area. Pathologic diagnosis revealed interstitial pneumonia with epithelioid granuloma and cholesterin-like substance, which were indicative of hypersensitivity pneumonia (Fig. 3). The patient’s symptoms improved during travel, worsened when she returned home, and improved after she moved into a new house. Therefore, she was diagnosed with chronic hypersensitivity pneumonitis.¹

FIGURE 1: Chest computed tomography scan.

FIGURE 2: Lung biopsy. A hole was made in the bronchial wall by using forceps.

FIGURE 3: Hematoxylin-eosin staining of the biopsied specimen.

DISCUSSION

We were able to visualize the lung alveoli directly by the bronchoscope at the tenth-generation bronchus in a patient with marked traction bronchiectasis and we performed lung biopsy safely under the direct vision avoiding the surrounding vessels. To our knowledge, this is the first report describing direct visualization of the alveolar area using conventional white light bronchoscopy. Probe-based confocal laser endomicroscopy (pCLE) is useful for visualizing alveoli.² The pCLE probe can be inserted through the biopsy channel of the conventional bronchoscope into the alveolar area, and the alveoli can be visualized at a lateral resolution of 3 μm. Although the pCLE system appears to be useful for visualizing and diagnosing cellular or extracellular details,² the biopsy forceps must be reinserted to obtain tissue. In the case reported herein, the lung alveoli were directly visualized through the bronchial wall at the tenth-generation bronchus and we performed lung biopsy safely through the bronchial wall under direct vision avoiding injury to the surrounding vessels. The routine performance of safe true “trans”-bronchial lung biopsy will be possible in the future if a thin bronchoscope with high-quality imaging and a working channel is developed.