Ancillary testing in lung cancer diagnosis

Abstract

The pathologic diagnosis of lung cancer historically has relied primarily on morphologic features of tumors in histologic sections. With the emergence of new targeted therapies, the pathologist is called upon increasingly to provide not only accurate typing of lung cancers, but also to provide prognostic and predictive information, based on a growing number of ancillary tests, that may have significant impact on patient management. This review provides an overview of ancillary tests currently used in the pathologic diagnosis of lung cancer, with a focus on immunohistochemistry and molecular diagnostics.

Figure 1

Immunohistochemistry stains in squamous cell carcinoma and adenocarcinoma of lung. H&E: hematoxylin and eosin; CK: cytokeratin; TTF-1: thyroid transcription factor 1. Squamous carcinomas are typically positive for CK5/6 and P63, and negative for CK7 and TTF-1, with the reverse profile for adenocarcinoma although this case of squamous cell carcinoma demonstrates focal weak staining for CK7.