Introduction The definitive diagnosis of pleural malignancy depends upon histological proof obtained via pleural biopsy. CT is reported to have a high sensitivity and specificity for the diagnosis of malignant pleural disease, and is part of the routine diagnostic work up of these patients. However, studies assessing the sensitivity of CT for pleural malignancy were carried out in relatively small cohorts of patients, and there remains a need for further data. The aim of this study was to assess the sensitivity and specificity of CT in detecting pleural malignancy (both primary and metastatic) prior to definitive histology obtained via thoracoscopy in a large cohort of patients with suspected malignant pleural disease.

Methods Retrospective review of thoracoscopy procedures carried out between 2010 and 2012 at the Churchill Hospital, Oxford, comparing histological results from thoracoscopy with the CT reported diagnosis before the procedure.

Results A total of 136 procedures were assessed. Thoracoscopic pleural biopsies were successfully obtained for histological analysis in 121 (89%) cases. Of these, 87 (72%) had CT chest scans prior to the procedure for which reports were available, and were included in this analysis. A total of 45/87 (52%) cases had a diagnosis of malignant pleural disease on the basis of the thoracoscopic biopsies. In those with a final histological diagnosis of malignancy, 25/45 had a prior CT report indicating malignant pathology, whereas 20/45 had a CT reporting no evidence of pleural malignancy (sensitivity of CT for a diagnosis of malignant pleural disease=55.6%, 95% CI 41.0% to 70.1%). Of the 42 cases with a thoracoscopic biopsy demonstrating benign pathology, 9 had CTs reporting malignant pathology (specificity for CT=78.6%, 95% CI 66.1% to 90.9%).

Conclusion CT appears to be less sensitive (56%) than previously reported, with a specificity (79%) similar to the previous literature. This difference may reflect changing patterns of disease or changes in the use of invasive biopsy techniques. The data suggests that the use of CT alone in determining which patients should have invasive pleural biopsies should be re-evaluated, and further studies to define the diagnostic pathway are now required.