The value of computed tomography for predicting empyema-associated malignancy

To determine the value of computed tomography (CT) scanning in detecting associated malignancy in patients with chronic empyema.

Two radiologists retrospectively reviewed CT scans of 112 consecutive patients with chronic empyema and arrived at a consensus about the findings. Among these patients, 6 were confirmed by pathology evaluation to have empyema-associated malignancy (EAM), including 4 lymphomas. The CT scans were evaluated for the presence of the following findings: a mass in the empyema sac; mass involvement of the extrapleural fat, chest wall, rib, and lung; bulging of the empyema sac; nodular pleural thickening; empyema involvement of the mediastinal pleura; presence of lung nodules (>1 cm); and mediastinal lymph node enlargement. The association between the CT findings and the EAM was analyzed with the Fisher exact test. A multiple logistic regression analysis was used to determine the predictive variables for EAM. Sensitivity, specificity, and positive predictive value were calculated for each finding.

All CT findings, except rib involvement and bulging of empyema sac, were significantly associated with EAM (P<0.05). The finding of the presence of a mass, extrapleural fat, and mediastinal involvement showed relatively high sensitivity (100%, 67%, 67%, respectively) and specificity (81%, 87%, 91%, respectively). A bulging of the empyema sac and nodular pleural thickening showed 100% sensitivity, but low specificity (39% and 44%, respectively). Findings from the multiple logistic regression analysis revealed that the presence of a mass and empyema of the mediastinal pleura were significant variables associated with EAM (P<0.05).

Although many CT findings are associated with EAM, most showed either low positive predictive value or low sensitivity. A variety of CT findings should be considered when evaluating CT image-based detection of EAM.