[Bronchiolo-alveolar cell carcinoma (clear cell adenocarcinoma)--report of 6 cases].

6 cases of bronchiolo-alveolar cell carcinoma proven surgically and histologically were studied. Under the microscope, it was shown that the columnar tumor cells lined the inner alveolar walls and the bronchiolar epithelium revealed malignant changes. Diagnosis of bronchiolo-alveolar cell carcinoma was established. Under the electron microscope, in addition to its adenocarcinomatous features, tongue-like protrusions were present on the cell surface and abundant round electron-dense granules were accumulated above the nuclei. These were in accordance with the characteristics of clear cell adenocarcinoma. In 4 cases, lamella bodies were present in a few tumor cells. It suggests that the clear cell adenocarcinoma be able to synthesize round electron-dense granules and lamella bodies.