Utility of small biopsies for diagnosis of lung nodules: doing more with less

Small biopsies obtained by core needle or bronchoscopy are commonly used for diagnosis of lung nodules. This review provides guidance in two key areas of interpretation of small lung biopsies. The first part answers common questions regarding the immunohistochemical subclassification of non-small cell lung carcinomas that cannot be classified by standard criteria on hematoxylin-eosin-stained sections of small lung biopsies. The second part discusses common benign entities that can be diagnosed in core needle biopsies of lung nodules, such as granulomatous inflammation, parenchymal scars and organizing pneumonia. The approach to cases in which malignant cells are absent and features of a specific benign diagnosis are lacking is also addressed.