Background Pulmonary cystic nodules are a relatively frequent finding in chest computed tomography (CT). There is a possible association between this finding and lung cancer. Aim To report eight patients with malignant lung cystic lesions. Material and methods Retrospective analysis of images in a CT database from 2007 to 2015, looking for cystic lesions of the lung with wall thickening, whose pathological diagnosis was lung cancer. Results We identified eight patients with cystic nodules aged 44 to 77 years, of which five were women. Six were active and two former smokers. The pathological diagnosis was adenocarcinoma in seven cases and squamous cell in one. The mean diameter of the cystic lesions was 11.5 mm. The mean diagnostic delay time was 871 days (range 0-1592). The main finding was a gradual thickening of the nodule walls. Conclusions The presentation of lung cancer as cystic nodules is uncommon. In this series, the change in morphology due to a thickening of the walls with or without a diameter increase, was the clue for the diagnosis.