Dry pleural dissemination in non-small cell lung cancer: prognostic and diagnostic implications

To compare prognostic differences between dry pleural dissemination (DPD) and wet pleural dissemination (WPD) in patients with non-small cell lung cancer (NSCLC) andto review the applicability of computed tomographic (CT) findings of DPD for rendering the diagnosis of this disease.

The institutional review board approved this retrospective study, and informed patient consent was waived. Of 98 patients (male-to-female ratio, 55:43; mean age, 60 years ± 12) with NSCLC, 20 patients had pathologically proved DPD, and the remaining 78 patients had pathologically proved WPD. Twelve patients, who had been lost to follow-up, were excluded from survival analysis. Observers looked for CT findings of multiple pleural or fissural nodules (more than six in number) and uneven thickening or bandlike thickness. Survival after initial presentation was analyzed and compared between patients with DPD (n = 19) and patients with WPD (n = 67) by using the Kaplan-Meier method and the log-rank test. The sensitivity of CT for depicting DPD was also calculated.

Median survival after initial presentation was significantly longer in patients with DPD than in patients with WPD; it was 38 months (95% confidence interval [CI]: 29.9 months, 46.0 months) in patients with DPD and 13 months (95% CI: 9.8 months, 16.2 months) in patients with WPD (P <.001). CT helped identify DPD in 90% (18 of 20) of patients with pathologically proved DPD. Multiple pleural or fissural nodules were noted on CT images in 16 (80%) of 20 patients. Uneven or bandlike pleural thickening was recognized in 15 (75%) patients.

Patients with DPD show better survival than patients with WPD. CT helps suggest strongly the presence of DPD preoperatively.