Cytological findings of pre-invasive bronchial lesions detected by light-induced fluorescence endoscopy in a lung cancer screening system

Lung cancer is a global epidemic and the number one cause of death among all cancers, with a very high morbidity. A new strategy for the treatment of lung cancer is the detection and eradication of pre-invasive bronchial lesions before they become invasive carcinomas. We conducted a detailed investigation into the use of fluorescence bronchoscopy in the detection of pre-invasive bronchial lesions in patients with sputum cytology suspicious or positive for malignancy. We also studied the distinctive cytological findings in the sputum specimens corresponding to the pre-invasive bronchial lesions. Sputum examinations were performed by mass screening a high-risk group of participants. From 1997 to 1999, 61 participants with sputum cytology suspicious or positive for malignancy were referred to our institute, and were examined with both white-light and fluorescence bronchoscopy. For the cytological findings, the collection of sputum was performed in the early morning. Conventional white-light examinations were first performed, and areas with abnormal findings were recorded for subsequent biopsy. Fluorescence bronchoscopy examinations were then carried out. Biopsy specimens for a pathological examination were taken from all the suspicious or abnormal areas discovered by the white-light bronchoscopy, or fluorescence bronchoscopy examination, or both. The laser-induced fluorescence bronchoscopic examination showed a high sensitivity for invasive carcinoma, carcinoma in situ, as well as severe, moderate, and mild dysplasia. In the sputum cytological findings, a thickened cytoplasm and slight hyperchromasia were frequently observed in the mild dysplasias compared with the squamous cells without atypia. Hyperchromasia and an Orange G (OG)-philic cytoplasm of squamous cells were frequently observed in the moderate compared with the mild dysplasias. A thickened cytoplasm, a nuclear pleomorphism, a thickened nuclear rim, a coarse chromatin, an uneven chromatin distribution, and an OG-philic cytoplasm were frequently observed in the carcinomas in situ and severe dysplasias compared with the moderate dysplasias. We found that the use of fluorescence bronchoscopy in addition to conventional white-light examination can enhance the detection and localization of pre-invasive bronchial lesions in patients with sputum cytology suspicious or positive for malignancy. Sputum cytology is therefore a potential approach to diagnosing pre-invasive bronchial lesions.