Are elastic stain and specialty sign out necessary to evaluate pleural invasion in lung cancers?

The seventh edition of American Joint Committee on Cancer (AJCC) staging system assigns lung cancers with visceral pleural invasion in the tumor size of 3 cm or less than 3 cm as T2 and without pleural invasion as T1. However, it may be difficult to distinguish with certainty between PL0 (no pleural invasion) and PL1 (extends through the elastic layer) on routine hematoxylin and eosin (H&E) stain. In this study, 25 cases of peripherally located lung adenocarcinoma were retrieved from the surgical pathology archives at the Asan Medical Center from May through June 2009. One representative H&E-stained slide was selected from each case and circulated to 31 pathology trainees and board-certified pathologists at Asan Medical Center who evaluated presence or absence of pleural invasion on H&E-stained slides. Elastic stain was used to determine the final status of pleural invasion for each case. The concordance rate of all pathologists with elastic stain results was, overall, 60.5%. The concordance rate of 2 lung specialists was 64%, better than the remaining faculty (54.7%). Fellows' and residents' evaluations were slightly more concordant than those of faculty responses (faculty overall, 56.4%; fellows, 62%; residents, 63.6%), but this difference was not statistically significant (P = .228). Our results confirm that pleural invasion status is difficult to discern with certainty on H&E-stained sections alone. Therefore, we recommend the routine use of elastic stain in evaluation of pleural invasion in all peripherally located lung cancers. Furthermore, our study indicates that subspecialty sign out may be preferable in evaluation of pleural invasion status.