Radiographically occult endobronchial obstruction in bronchogenic carcinoma

While central endobronchial tumors may become radiographically detectable when they cause significant endobronchial obstruction, the incidence of radiographically undetectable obstruction is not known. This study prospectively examined the incidence of radiographically undetectable completely obstructing lesions encountered during routine diagnostic bronchoscopy.

Patients referred for bronchoscopy at the San Diego Veterans Administration Medical Center because of suspected bronchogenic carcinoma formed the population base. Chest radiographs were interpreted routinely 24 hours prior to bronchoscopy. Patients found to have complete endobronchial obstruction during bronchoscopy were included in the analysis.

Eighty-one completely obstructing lesions were found in 77 patients. No radiographic signs of obstruction were found in 36 (44%) completely obstructing endobronchial lesions. There was no difference in the rate of radiographically occult tumors based on cell type. Obstruction of segmental bronchi was more likely to be undetectable than obstruction of more proximal airways. Chest radiographs were normal in 13 (16%). All 13 had risk factors for and symptoms suggestive of bronchogenic carcinoma.

Complete endobronchial obstruction due to bronchogenic carcinoma can occur frequently in patients at risk for lung cancer. The significant incidence of radiographically undetectable complete obstruction has implications for the diagnosis, staging, and assessment of treatment of lung cancer.