Roentgenographically occult bronchogenic squamous cell carcinoma involving mediastinal lymph nodes after removal of initial lesion by the diagnostic examination.

A 69-year-old male was suspected of having lung cancer by sputum cytology and diagnosed as roentgenographically occult squamous cell carcinoma (ROSCC) at the spur of left B(1+2)/B(3). However, after the first bronchoscopy, no suspicious lesion was detected by any examinations. Therefore, we considered that cancer cells had been removed completely by the initial examination, and the patient was followed up by sputum cytology, chest roentgenogram, and bronchoscopy. Sixteen months later from the initial examination, bronchoscopy was performed for follow-up. The bronchoscopic findings showed the elevation of the surface of left B(1+2) a+b, but the cytologic specimen by brushing toward B(1+2) a+b showed negative findings. However, the lesion had developed to polypoid-shaped tumor and obstructed B(1+2) a+b after the next 6 months. The tumor was diagnosed as squamous cell carcinoma, and hilar and mediastinal nodal involvement was suspected on chest computed tomography. The standard thoracotomy was performed and the pathological results showed positive for nodal involvement on hilus and mediastinum. The tumor is considered to arise from the residual cancer cells of initially detected ROSCC. In conclusion, although some ROSCCs regress by the diagnostic examinations, it is important to detect the recurrence of residual cancer cells as early as possible by intensive follow-up.