Démembrement des adénocarcinomes bronchopulmonaires : le point de vue du pathologiste

Prescription of personalized therapies in non-small cell lung carcinoma is mainly based on histological subtype and molecular abnormalities in tumor specimens. New guidelines for classification of NSCLC were published in 2011, especially updating adenocarcinoma classification and addressing the management of small biopsies and cytological preparations, the only material available for patients at an advanced stage. On small samples, the pathologist should separate adenocarcinoma from squamous cell carcinoma, using mucin staining and/or immunohistochemistry if necessary, keeping in mind not to use up the tumor material further required for molecular testing. The terms “bronchoalveolar carcinoma” (BAC) and “mixed subtype adenocarcinoma” are no longer used. The term “lepidic growth” is used to describe a non-invasive adenocarcinomatous component (formerly classified as BAC). New concepts like in situ adenocarcinoma and minimal invasive adenocarcinoma have emerged, defining tumors with a 5-year survival rate of 100 % after complete resection. Invasive adenocarcinomas are classified based on their predominant pattern (lepidic, acinar, papillary, solid, micropapillary) and this subclassification replaces grading. The former mucinous BAC is now classified as invasive mucinous adenocarcinoma. This article describes the major points of this new classification and underlines the role of the pathologist in the molecular testing for treatment selection.