Pit-fall sign on computed tomography predicts pleural involvement and poor prognosis in non-small cell lung cancer.

Pleural involvement by a peripheral non-small cell lung cancer (NSCLC) is an important prognostic factor, but the accurate preoperative evaluation is sometimes difficult. We have already identified a feature on computed tomography (CT) that suggests a possible pleural involvement (pit-fall sign, i.e. multiple linear strands between the nodule and chest wall and/or inter-lobar fissure), and the clinical impact was assessed in the present study. A total of 103 consecutive peripheral NSCLC patients were prospectively examined, and the sensitivity, specificity, and accuracy of pit-fall sign in the diagnosis of pleural involvement were 83.3, 76.1, and 78.6%, respectively. The 5-year survival rate of pit-fall sign-positive patients was 46.5%, which was significantly lower than that of pit-fall sign-negative patients (68.9%; P = 0.044), and the prognostic significance was confirmed by a multivariate analysis. In conclusion, the pit-fall sign on preoperative CT suggests a possible pleural involvement correlated with a poor prognosis.