Visceral pleural invasion in lung adenocarcinoma ≤3 cm with ground-glass opacity: a clinical, pathological and radiological study.

BACKGROUND

Visceral pleural invasion (VPI) had been demonstrated as an aggressive sign in non-small cell lung cancers (NSCLC). However, its incidence and clinical relevance in early lung cancer showing ground glass nodules (GGNs) has not been clarified.

METHODS

All consecutive surgically treated patients with solitary GGNs between 2009 and 2013 were reviewed retrospectively. Inclusion criteria were defined as lesions ≤3 cm with pleura abutting on computed tomography (CT) scan and pathologically confirmed NSCLC.

RESULTS

Out of 156 enrolled patients, 38 had pathologically confirmed VPI. The incidence of VPI was 41.5% (27/65) if the tumor diameter was larger than 2.0 cm and 14.3% (13/91) if diameter was smaller than 2.0 cm (P<0.001). Further, the incidence was 17.4% (12/69) in pure GGNs and 32.2% (28/87) in part-solid GGNs (P=0.040). The tumor size and the nodule nodule-pleural relationship were significant predictors of positive VPI. In cases with pleural indentation, attachment, and closeness, the incidence was 38.1%, 25.5%, and 5.3%, respectively (P=0.001). All cases were PL0 and PL1, with no PL2 cases observed.

CONCLUSIONS

Although VPI was visible in both pure/mix GGNs, it was more common in larger (>2 cm) GGNs. The radiographic findings of nodule abutment or a pleural tag did not reliably predict or exclude VPI. In patients with GGNs, a low rate of PL2 invasion may be observed.