Thin-wall cystic lung cancer is becoming of increasing interest in the study of pulmonary medicine. Consequently, more and more different images and pathologic manifestations have been found. The purpose of this article is to find pathologic characteristics and try to explain the formation mechanism of thin-walled cystic lung cancer.Sixty-five patients with this special lung cancer were analyzed retrospectively based on the review of medical records, radiologic findings, and pathologic changes.We found 3 pathologic types: adenocarcinoma, squamous cell carcinoma, and lymphoma. There were 60 cases of adenocarcinoma, 4 cases were squamous cell carcinoma, and only 1 lymphoma. Tumor cells, pulmonary vessels, fibrous tissues, and residual bronchi are the pathologic basis of different image findings.Thin-walled cystic lung cancers are mostly adenocarcinoma, but other pathologic types can also appear, such as squamous cell carcinoma and lymphoma. We can see that a large amount of fibrous tissues were generated by tumors around the bronchus, resulting in airway stenosis and degeneration. Tumor cells also can invade the bronchial wall and cause structural damage. All these lesions are similar to 1-way valves which can cause gas accumulation in the tumor area and result in thin-walled cystic lung cancer.