Mitosis trumps T stage and proposed international association for the study of lung cancer/american thoracic society/european respiratory society classification for prognostic value in resected stage 1 lung adenocarcinoma.

INTRODUCTION: We investigated whether a group of pathologists could reproducibly apply the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) classification for lung adenocarcinoma to a cohort of stage 1 tumors and whether this architectural classification and/or other parameters could demonstrate survival advantage. METHODS: A total of 145 cases of 7 edition of tumor, node, metastasis stage 1 adenocarcinoma were retrospectively reviewed for predominant architectural pattern, including cribriform pattern, nuclear grade, mitotic index, and necrosis. The parameters were assessed for reproducibility and survival and using multivariate analysis, compared with stage, age, and sex. RESULTS: The majority of tumors had a mixed architecture with the acinar pattern being the most common predominant architecture. Micropapillary and cribriform architecture were the least frequent patterns. This study demonstrated that a group of five pathologists could reproducibly apply the IASLC/ATS/ERS classification. Although there were insufficient cribriform-predominant adenocarcinomas for assessment, when the percentage of all cribriform was combined with other architectures, it was associated with a worse prognosis. The majority of the parameters assessed demonstrated significance with univariate analysis but only mitotic index, as assessed by the highest count/10 high-power fields remained significant with multivariate analysis. CONCLUSION: In this study of resected stage 1 primary lung adenocarcinoma, we found mitotic index to be the only independent prognostic marker. It was more closely associated with outcome than either pathologic T stage or IASLC/ATS/ERS architecture-based classification. Further validation of concordance and reproducibility in reporting mitotic index, as well as validation of prognostic significance, needs to be undertaken in independent data sets.

Tissue microarray technology and findings for diagnostic immunohistochemistry.

AIMS: This study was undertaken to determine the validity and viability of tissue microarray (TMA) technology in assessing diagnostic immunohistochemistry (IHC) at a single laboratory site. METHODS: IHC using 57 primary antibodies was performed on a TMA paraffin block containing 89 cores of duplicate previously identified 1 mm diameter tissue specimens. IHC was interpreted by a histology scientist with IHC experience, with pathologist assistance if required. Review of the literature was performed to investigate cases of unexpected immunoreactivity. RESULTS: 55 of 57 antibodies had expected positive staining against the TMA tissue panel that correlated with the original paraffin blocks. Immunostaining of duplicate 1 mm cores correlated with the originally sourced paraffin block in 42 of 43 (98%) tissue types. Some antibodies had unexpected positive immunoreactivity. DISCUSSION: TMA technology can be utilised effectively in the diagnostic IHC laboratory as a universal positive multiple tissue control block for routine IHC, and can provide valuable information for the benefit of histology scientists and pathologists with respect to interpretation of IHC staining.