Increased frequency of bronchiolar histotypes in lung carcinomas associated with idiopathic pulmonary fibrosis.

The immunohistochemical characterization of carcinomas arising in IPF patients shows striking divergence from that in non-IPF smokers. The prevalence of rare entities showing bronchiole-related markers is in line with the hypothesis that these tumours arise from transformed small airways in honeycomb lung areas where abnormal bronchiolar proliferation takes place.