The use of electron microscopy for the diagnosis of cancer in bronchial biopsies

To investigate whether electron microscopic examination of bronchial biopsy specimens was of any additional value in the diagnosis of lung cancer, we examined 235 consecutive biopsy specimens embedded in Epon. Semithin sections were used to establish a light microscopic diagnosis, and the results were compared with those of electron microscopy. Ninety-six biopsies contained tumor. In 13 instances, the light microscopic diagnosis had to be revised after electron microscopic examination. Another 5 biopsies contained tissue suspected to be tumor; in 1 biopsy this possibility could be ruled out. Three biopsies contained tumor suspected of being small cell cancer, and this diagnosis was confirmed by electron microscopy. Electron microscopy was helpful in 17 of 106 biopsies. Histopathologic examination of surgically resected material from 18 patients confirmed the electron microscopic results of biopsies. We conclude that electron microscopy of bronchial biopsy specimens gives important additional information for accurate diagnosis. For practical purposes, however, specimens should be embedded in Epon or glycol-methacrylate for light microscopy. Developments in immunohistologic techniques will change choices of histologic techniques.