Abstract
A 62-year-old man was referred to our hospital after category E was detected by sputum cytology screening. The chest X-ray film and computed tomography failed to reveal an abnormal shadow. Bronchofiberscopic findings did not show the hilar type lung cancer, and washing cytology showed no cancer cells. Three months later, squamous cell carcinoma was diagnosed by washing cytology from the right lung. After one week, cancer cells were obtained by washing cytology from the right lower lobe bronchus, and after admission, cancer cells were obtained by washing cytology from right B^6. The clinical stage was occult carcinoma (TXN0M0), right S^6 segmentectomy was performed. The pathologic specimen showed moderately differentiated squamous cell carcinoma in the peripheral S^6c. The largest tumor dimension was 2.8mm×2.5mm. The pathological stage was I (T1N0M0).
