胸腔积液是胸部恶性肿瘤及非肿瘤性疾病的重要并发症。癌性胸腔积液大多来自肺癌,也可来自其它部位恶性肿瘤的胸膜转移。确定胸腔积液的病因是针对性治疗的前提。胸腔积液中的细胞学检查有助于作出正确诊断。积液中的CEA含量变化对疑为恶性来源但未能查出肿瘤细胞的病例有重要参考价值。作为肺癌肿瘤 Pleural effusion is an important complication of thoracic malignancy and non-neoplastic diseases. Most cancerous pleural effusions come from lung cancer, but also from pleural metastasis of malignant tumors elsewhere. Determining the cause of pleural effusion is the premise of targeted treatment. Cytological examinations in pleural effusions can help make the correct diagnosis. The change of CEA content in the effusion has important reference value for the suspected malignant source but failed to detect the tumor cell. As a tumor of lung cancer