Interobserver agreement among histological patterns and diagnosis in lung adenocarcinomas

The aim of this study was to investigate the interobserver agreement in determination of the dominant histological pattern and the final diagnosis in lung adenocarcinomas.

A total of 12 patients with a diagnosis of primary lung adenocarcinoma were included in the study. Twelve pathologists from eight study centers were asked first to determine the dominant histological pattern in these cases and then to decide whether the final diagnosis was in situ, minimally invasive or invasive adenocarcinoma.

The kappa value for the agreement in determining the dominant pattern among the pathologists was 0.36 (p < 0.001), with the values for the lepidic, acinar, papillary, solid, micropapillary patterns and mucinous character of adenocarcinoma being 0.34, 0.28, 0.30, 0.80, 0.16 and 0.38 respectively (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001, p < 0.001). None of the cases was diagnosed as in situ adenocarcinoma. On the other hand, the kappa value for the agreement in differentiating minimally invasive from invasive adenocarcinoma among reviewers was 0.17 (p < 0.001).

The agreement among pathologists in determining the subtype of lung adenocarcinomas that depends on the identification of the dominant pattern was at intermediate level. In addition, the agreement in deciding whether the case is minimally invasive or invasive, was at low level. The criteria defining the histological patterns should be clarified and described in more detail. Educational activities and larger multicenter studies might be helpful in improving the agreement and standardization.