[Clinical analysis of primary lung cancer with a thin-walled cavity to explain the mechanism of thin-walled cavity formation].

We report 8 rare cases of primary lung cancer which showed a thin-walled cavity on chest X-ray and CT. We analyzed 8 cases (7 men, 1 woman) of primary lung cancer with thin-walled cavities admitted to our hospital between 1995 and 2006. The subjects were aged between 45 and 84 years of age (median: 72 years old). The reason for detection was treatment for tuberculosis in 1 case, ileus owing to metastasis to the small intestine in 1 case and tension pnumathorax 1 case, while 5 cases had abnormal chest x-ray film shadows without symptoms. Histologically, there were 5 cases of adenocarcinoma, 2 of squamous cell carcinoma, and 1 of adenosquamous cell carcinoma. Though various reports on the mechanism of the development of thin-walled cavity formation have been made, we suggest that it mainly develops by a check-valve mechanism, based on evaluation of the clinical course.