Objective To study the diagnostic value of MSCT in cystic lung cancer with ground glass opacity(GGO),and improve understanding of the disease as well as diagnostic accuracy.Methods 2 1 cases of pathologically confirmed cystic lung cancer with GGO were analyzed retrospectively,all patients were examined by MSCT.CT features of the GGO and the cysts,including bronchovascular convergence sign,speculation sign,pleural indentation sign,lobulation,thickness and uniformity of the cyst wall,septa and the location of the lesion were analyzed.Results The image findings of the 21 cases of the cystic lung cancer with GGO included:bronchovasular convergence sign in 6 cases(28.6%),speculation sign in 10 cases(47.7%),pleural indentation sign in 12 cases(57.1%),lobulation in 8 cases(38.1%),10 cases(47.7%)showed pure GGO.The cyst wall was(1.7±0.9)mm in thickness and the cyst was (13.2±7.0)mm in diameter.Cyst wall was uniform in 9 cases(42.9%),septa was seen in 14 cases(66.7%),cysts of 16 cases(76.1%)were located in the upper lobes of the lung,1 case(4.7%)had distinctly mediastinal lymph node metastasis.Air-fluid lever,mural nodule or intrapulmonary metastasis were not present in any of the cases.Conclusion The majority of the cystic lung cancer with GGO are adenocarcinoma.In addition of the interference of its prominent cystic features on MSCT,the cystic lung cancer have characteristics of lung cancer with GGO.By analyzing its CT features,diagnostic accuracy can be improved before operation.