Transbronchial lung biopsy in sarcoidosis. An approach to determine the optimal number of biopsies.

In order to determine if the diagnostic yield of the transbronchial lung biopsy in sarcoidosis is dependent upon the number of biopsies, a study was designed to examine individual specimens from 6 biopsies in patients with Stage II sarcoidosis. It was found that the probability of obtaining a positive specimen per biopsy was 46%, and this percentage remained constant for each biopsy. The diagnostic yield followed a logarithmic curve, gradually increasing from 1 through 4 biopsies until about 90% of true positive diagnoses were obtained, then approaching a plateau with successive biopsies. We therefore recommend that 4 transbronchial lung biopsies are sufficient to diagnose stage II sarcoidosis in the majority of patients with diffuse lung disease.