CT findings of pleural dissemination in primary lung cancer

To evaluate the CT findings of pleural dissemination in primary lung cancer and the limitations of CT scanning in detecting pleural dissemination in primary lung cancer. Primary lung cancer with pleural dissemination was diagnosed in 68 patients and confirmed by pleural biopsy, cytology and surgery, and these cases were the subject of this study. Adenocarcinoma accounted for 49, squamous cell carcinoma for 13 and small cell carcinoma for six. Eight CT features, namely the amount of pleural effusion, the contour, extent and location of pleural thickening, the shortest distance between pleura and mass, pleural calcification, pleural tail sign and the extent of extrapleural fat proliferation, were evalusted. Pleural effusion was noted in 51 of 68 patients(75%), though in most case(70%), the amount of this was small. Among 42 patients(62%) in whom thickened pleura, were noted, pleural thickening was thin and irregular in 22(52%), thick and irregular in 16(38%), and thin and regular in 4(10%). The extent of pleural thickening was multifocal in 22 patients(52%), diffuse in 16(38%), and circumferential and single in two(5%). Pleural thickening was more frequently noted at the posterior than the anterior pleura. Pleural abutting was seen in 53 patients(78%). In ten patients(15%), chest CT scans revealed no perceptible pleural abnormalities. If in primary lung cancer, the primary lung mass contacts the pleura, and if pleural thickening, even when slight, shows marginal irregularity, pleural dissemination should be considered. Although CT scanning is very useful for the detection of pleural dissemination in primary lung cancer, about 15% of patients showed no perceptible pleural abnormalities. Other diagnostic modalitie such as thoracoscopy are mandatory for the correct diagnossis of pleural dissemination in primary lung cancer.=20