A 62year-old man visited our institute with a coin lesion on chest film. By sputum cytology by Saccomanno's method (modified by Sato) atypical cells in cluster were found with following characteristics; Abundant cytoplasm with vacuoles, large round nuclei which are deviated in part, lots of chromatin, and one round nucleoli. Also in the bronchial brushing smear, atypical cells were found in sheets.
Right lower lobectomy under the diagnosis of lung cancer revealed that the lesion was pulmonary hamartoma. The pathological examination showed that the tumor was surrounded by the monolayer cuboidal epithelium. And atypical proliferation was noted in the epithelium.
The origin of atypical cells was discussed in cytological and histological point of view.
