Step section preparation of transbronchial lung biopsy. Significance in the diagnosis of diffuse lung disease.

We retrospectively prepared step sections of nondiagnostic TBLB materials obtained from patients with diffuse or multiple lung disease and evaluated the diagnostic significance of the step section method. Among 112 patients with nondiagnostic TBLB findings, the preparation of step sections resulted in specific findings in seven cases. Step sections were especially useful for the detection of epithelioid granulomas and tumor tissue in patients with sarcoidosis and lymphangiosis carcinomatosa, respectively, but their contribution to the diagnosis of hypersensitivity pneumonitis, collagen-vascular disease, Mycoplasma pneumonia and pneumoconiosis was relatively small. In addition, step sections were useful for the detection of bronchiolitis obliterans affecting respiratory bronchioles. Overall, the examination of step sections was considered to be clinically useful in 30 cases (26.8 percent). Accordingly, the examination of step sections can be recommended before a further diagnostic procedure is chosen, if a TBLB performed in patients with diffuse or multifocal lung disease is nondiagnostic.