The Use of a Novel Immunohistochemical Triple Cocktail in the Subclassification of Resected Non–Small Cell Lung Carcinomas: A Comparative Study With Morphology and Traditional Immunohistochemistry

Use of dual-marker staining to differentiate between lung squamous cell carcinoma and adenocarcinoma

OBJECTIVE

To assess the value of dual-marker immunostaining for detecting p40 and napsin A, and cytokeratin 5/6 (CK5/6) and thyroid transcription factor 1 (TTF1) in single sections of lung cancer tissue, for differentiating between lung squamous cell carcinoma and adenocarcinoma.

METHODS

Lung cancer tissue sections from 58 patients were stained by dual-marker immunostaining using a mixtures of anti-p40 and anti-napsin A, and anti-CK5/6 and anti-TTF1 primary antibodies. Sections stained with single markers were used as controls. Nuclear or cytoplasmic staining was considered as indicating positive p40 or napsin A expression, respectively, and cytoplasmic or nuclear staining was considered as indicating positive CK5/6 or TTF1 expression, respectively.

RESULTS

p40/napsin A and CK5/6/TTF1 dual-marker staining showed high sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of squamous cell carcinoma and adenocarcinoma respectively. There were no differences in marker expression between dual-marker and single-marker staining.

CONCLUSIONS

Dual-marker immunostaining is a relatively easy, time- and cost-conserving staining method for detecting two markers in a single section using one procedure and one chromogen. p40 and napsin A, and CK5/6 and TTF1 dual-marker staining were suitable for the differential diagnosis of lung squamous cell carcinoma and adenocarcinoma.

The impact of immunohistochemistry on the classification of lung tumors

INTRODUCTION

To highlight the role of immunohistochemistry to lung cancer classification on the basis of existing guidelines and future perspectives.

AREAS COVERED

Four orienting key-issues were structured according to an extensive review on the English literature: a) cancer subtyping; b) best biomarkers and rules to follow; c) negative and positive profiling; d) suggestions towards an evidence-based proposal for lung cancer subtyping. A sparing material approach based on a limited number of specific markers is highly desirable. It includes p40 for squamous cell carcinoma ('no p40, no squamous'), TTF1 for adenocarcinoma, synaptophysin for neuroendocrine tumors and vimentin for sarcomatoid carcinoma. A close relationship between genotype and phenotype also supports a diagnostic role for negative profiles. Expert commentary: Highly specific and sensitive IHC markers according to positive and negative diagnostic algorithms seem appropriate for individual patients' lung cancer subtyping.