Probability of a positive transbronchial lung biopsy result in sarcoidosis

Forty-one consecutive patients with suspected sarcoidosis underwent pulmonary function testing and transbronchial lung biopsy at three community teaching hospitals. Transbronchial biopsy disclosed noncaseating granulomas in 22 of 23 patients (96%) in whom parenchymal disease was roentgenographically apparent and in eight of 18 patients (44%) in whom it was not. The stage of the disease as determined by the chest roentgenogram was the most reliable determinant for a positive biopsy result. Not the presence of cough, dyspnea, or constitutional symptoms or pulmonary function as measured by forced vital capacity and carbon monoxide diffusing capacity served to predict a positive transbronchial biopsy finding any more accurately than did the roentgenographic staging of the disease itself. This study suggests that while transbronchial lung biopsy may be an acceptable initial diagnostic procedure in suspected sarcoid patients without parenchymal lung disease, clinical symptoms and pulmonary function abnormalities are not helpful in predicting the liklihood of a positive biopsy result.